WO2025015681A1 - Electrode assembly, battery cell, battery, and electric device - Google Patents

Abstract

An electrode assembly, a battery cell, a battery, and an electric device. The electrode assembly comprises a first electrode sheet, a second electrode sheet, and a separator. The first electrode sheet and the second electrode sheet have opposite polarities. The separator is used for separating the first electrode sheet from the second electrode sheet. The first electrode sheet, the second electrode sheet, and the separator are wound in a winding direction and form a bent area. The electrode assembly further comprises an insulating member. At least part of the insulating member is located in the bent area and between the first electrode sheet and the second electrode sheet.

Description

Electrode assembly, battery cell, battery and electrical device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application 202310886910.3, filed on July 19, 2023, entitled “Electrode assembly, battery cell, battery and electrical device,” the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to the field of batteries, and in particular to an electrode assembly, a battery cell, a battery, and an electrical device.

Background Art

With the development of battery technology, battery cells are used in more and more fields and are gradually replacing traditional petrochemical energy in the field of automotive power. Battery cells can store chemical energy and controllably convert chemical energy into electrical energy. In recyclable battery cells, the active material can be activated by charging after discharge and continue to be used.

How to improve the reliability of battery cells is an important research direction in the industry.

Summary of the invention

The present application provides an electrode assembly, a battery cell, a battery, and an electrical device, which can improve reliability.

In a first aspect, the present application provides an electrode assembly, comprising a first pole piece, a second pole piece and a separator, wherein the first pole piece and the second pole piece have opposite polarities, the separator is used to separate the first pole piece and the second pole piece, and the first pole piece, the second pole piece and the separator are wound along a winding direction to form a bending region. The electrode assembly also includes an insulating member, at least a portion of which is located in the bending region and between the first pole piece and the second pole piece.

The above technical solution sets an insulating part in the bending area. Even if ion precipitation occurs in the bending area, such as lithium ion precipitation, the insulating part can block the lithium dendrites generated by lithium precipitation to a certain extent, reduce the risk of conduction between the first pole piece and the second pole piece, and improve the reliability of the electrode assembly and the battery cell.

In some embodiments, the first pole piece and the second pole piece each include a plurality of bending portions located in the bending region, and at least one bending portion of the first pole piece is a first bending portion. An insulating member adjacent to the first bending portion is disposed on at least one side of the first bending portion.

The insulating member can separate the first bending portion from the second pole piece, reduce the risk of the first bending portion and the second pole piece being connected, and improve reliability. The insulating member can also shield the first bending portion when the first bending portion is broken, reducing the risk of short circuit.

In some embodiments, the electrode assembly further comprises a straight region connected to the bent region, and both ends of the insulating member along the winding direction are located in the straight region.

The insulating member passes through the bending area as a whole to insulate the first bending portion from the second pole piece, and reduce the possibility that the end of the insulating member along the winding direction is located in the bending area due to assembly error, thereby reducing the first bending portion and the second pole piece. The risk of diode conduction is reduced, improving reliability.

In some embodiments, the first electrode is a positive electrode, and the second electrode is a negative electrode. At least one bend of the second electrode is a second bend adjacent to and located inside the first bend. The insulating member separates the first bend from the second bend.

When ion precipitation (such as lithium ion precipitation) occurs in the second bend portion, the insulating member can also block the lithium dendrites generated by lithium precipitation to a certain extent, reduce the risk of lithium dendrites connecting the first bend portion and the second bend portion, and improve the reliability of the electrode assembly and the battery cell.

In some embodiments, at least the innermost bending portion of the first pole piece is a first bending portion, and at least the innermost bending portion of the second pole piece is a second bending portion.

The innermost bend of the first pole piece has the largest degree of bend, that is, the positive electrode active material of the innermost bend of the first pole piece has the most serious phenomenon of shedding; the innermost bend of the second pole piece has the largest degree of bend, that is, the negative electrode active material of the innermost bend of the second pole piece has the most serious phenomenon of shedding, and the innermost bend of the second pole piece is most likely to have ion precipitation. The above technical solution sets at least the innermost bend of the first pole piece as the first bend, and sets at least the innermost bend of the second pole piece as the second bend, which can reduce the risk of conduction between the two innermost bends of the bend area and improve reliability.

In some embodiments, the insulating member is independently arranged on the first bending portion to facilitate installation of the insulating member. The insulating member and the first bending portion are independently arranged to reduce the impact on the insulating member when the first bending portion expands and deforms, reduce the risk of stretching and cracking of the insulating member, and improve the reliability of the insulating member.

In some embodiments, both ends of the insulating member along a first direction extend beyond the first bending portion, and the first direction is perpendicular to the winding direction.

When the battery cell is subjected to external impact, both ends of the insulating member along the first direction can play a supporting role, thereby reducing the vibration amplitude of the first bending portion, reducing the impact force on the first bending portion, reducing the shedding of active materials, and improving the cycle performance of the battery cell.

In some embodiments, both sides of the first bend are provided with insulating members adjacent thereto. The insulating members can separate the two sides of the first bend from the second pole piece, thereby further reducing the risk of conduction between the first bend and the second pole piece and improving the reliability of the electrode assembly and the battery cell.

In some embodiments, the insulating members located on both sides of the first bending portion are respectively a first insulating member and a second insulating member. Two ends of the first insulating member along the first direction are respectively connected to two ends of the second insulating member along the first direction.

The first insulating member and the second insulating member are connected so that the whole formed by the two can be sleeved on the first pole piece, so that when the battery cell is subjected to external impact, the movement of the first insulating member and the second insulating member relative to the first bending portion is reduced, the insulation reliability of the first insulating member and the second insulating member is improved, and the risk of short circuit is reduced.

In some embodiments, the electrode assembly further comprises an adhesive layer, and at least one end of the first insulating member along the first direction is connected to the second insulating member through the adhesive layer. The adhesive layer can facilitate bonding of the first insulating member and the second insulating member.

In some embodiments, the first insulating member includes a first main body and a first connecting portion, the first connecting portion extending from an end of the first main body along a first direction. The second insulating member includes a second main body and a second connecting portion, the second connecting portion extending from an end of the second main body along the first direction. The first bending portion is located between the first main body and the second main body, and the adhesive layer is bonded between the first connecting portion and the second connecting portion.

The first main body and the second main body can cover the first bending part from both sides, so as to separate the two sides of the first bending part from the second pole piece, thereby further reducing the risk of the first bending part and the second pole piece being connected, and improving the reliability of the electrode assembly and the battery cell. The first connecting part and the second connecting part can be connected by a glue layer, so as to reduce the movement of the first main body and the second main body relative to the first bending part when the battery cell is subjected to external impact, improve the insulation reliability, and reduce the risk of short circuit.

In some embodiments, no adhesive layer is disposed between the first main body portion and the first bending portion, and no adhesive layer is disposed between the second main body portion and the first bending portion.

The above technical solution can save the amount of glue layer and improve the energy density of the battery. The first main body can be independently provided with the first bending part, and the second main body can be independently provided with the second bending part, which can reduce the impact on the insulating part when the first bending part is deformed, reduce the risk of stretching and cracking of the insulating part, and improve the reliability of the insulating part. Compared with the solution of bonding the first main body and the first bending part with a glue layer, the above technical solution can also reduce the risk of ion precipitation and improve the reliability of the battery cell.

In some embodiments, the first insulating member includes two first connecting parts, which extend from two ends of the first main body along the first direction respectively; the second insulating member includes two second connecting parts, which extend from two ends of the second main body along the first direction respectively. The two first connecting parts are respectively bonded to the two second connecting parts through adhesive layers.

The first insulating member and the second insulating member can be formed independently, and both can be attached to the first pole piece from two layers, which can simplify the assembly process.

In some embodiments, the first insulating member includes a first connecting portion, and the second insulating member includes a second connecting portion. An end of the first main body away from the first connecting portion is integrally connected to an end of the second main body away from the second connecting portion.

The above technical solution can reduce the amount of glue layer used, reduce the maximum size of the first insulating member and the second insulating member along the first direction, improve the energy density, and increase the connection strength between the first insulating member and the second insulating member.

In some embodiments, the adhesive layer includes acrylic resin and/or polyolefin resin. Both acrylic resin and polyolefin resin are adhesive and can firmly bond the first insulating member to the second insulating member.

In some embodiments, the acrylic resin includes one or more of acrylic acid-methacrylic acid copolymer, acrylic acid-butenoic acid copolymer, acrylic acid-itaconic acid copolymer, acrylic acid-maleic acid copolymer, acrylic acid-methyl methacrylate copolymer, acrylic acid-ethyl methacrylate copolymer, acrylic acid-n-butyl methacrylate copolymer, and acrylic acid-isobutyl methacrylate copolymer. The above materials have good chemical stability and electrochemical stability and are not easily soluble in electrolyte.

In some embodiments, the polyolefin resin includes any one or more of polypropylene, polyethylene, polybutadiene rubber, ethylene-propylene acetate copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, maleic anhydride modified polyolefin, polybutadiene-acrylonitrile, and styrene-maleic anhydride copolymer. The above materials have good chemical stability and electrochemical stability and are not easily soluble in electrolyte. Adding anhydride modified polar functional groups can significantly improve the adhesion.

In some embodiments, the material of the insulating member includes olefin polymer. Olefin polymer is generally non-sticky and has high tensile strength and impact resistance. When the electrode assembly is hot-pressed, the insulating member is not easy to crack, thereby reducing the possibility of lithium dendrites passing through the insulating member through microcracks of the insulating member and reducing the risk of short circuit.

In some embodiments, the olefin polymer includes one of polyethylene, polypropylene or polyimide. These materials have high tensile strength and impact resistance and are not prone to cracking during the hot pressing process of the electrode assembly.

In some embodiments, the tensile strength of the insulating member is 60 MPa-120 MPa. The insulating member has a high tensile strength, and is not easy to crack during the bending process of the insulating member and the hot pressing process of the electrode assembly, thereby reducing the possibility of dendrites (such as lithium dendrites) formed by ion precipitation passing through the insulating member through microcracks of the insulating member, thereby reducing the risk of short circuit.

In some embodiments, the tensile strength of the insulating member is 80 MPa-120 MPa, which can further reduce the risk of cracking of the insulating member.

In some embodiments, the first electrode is a positive electrode, and the second electrode is a negative electrode. The insulating member is used to prevent at least a portion of ions escaped from the first electrode from being embedded in the second electrode.

During charging, the ions released from the positive active material layer of the positive electrode sheet are at least partially blocked by the insulating member, so that the ions blocked by the insulating member cannot be embedded in the negative active material layer of the negative electrode sheet in the bending area, thereby reducing the risk of ion precipitation when the negative active material of the negative electrode sheet falls off. Although the negative electrode sheet has fewer ion embedding sites due to the shedding of the negative active material, the insulating member blocks at least a portion of the ions released from the positive electrode sheet, so the phenomenon of ion precipitation can be reduced.

In a second aspect, the present application provides a battery cell, which includes a housing and an electrode assembly provided by any embodiment of the first aspect, wherein the electrode assembly is accommodated in the housing.

In a third aspect, the present application provides a battery, comprising a plurality of battery cells provided by any embodiment of the second aspect.

In a fourth aspect, the present application provides an electrical device, which includes a battery provided by any embodiment of the third aspect, and the battery is used to provide electrical energy.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

FIG1 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

FIG2 is an exploded schematic diagram of a battery provided in some embodiments of the present application;

FIG3 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application;

FIG4 is a schematic diagram of an electrode assembly provided in some embodiments of the present application;

FIG5 is a partial cross-sectional schematic diagram of an electrode assembly provided in some embodiments of the present application;

FIG6 is another partial cross-sectional schematic diagram of an electrode assembly provided in some embodiments of the present application;

FIG7 is an enlarged schematic diagram of FIG6 at the circle frame;

FIG8 is a partial cross-sectional schematic diagram of an electrode assembly provided in some other embodiments of the present application;

FIG. 9 is an enlarged schematic diagram of the circle frame of FIG. 8 .

In the drawings, the drawings are not necessarily drawn to scale.

The reference numerals are as follows:

1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 5. Box; 5a. First box part; 5b. Second box part; 5c. Accommodation space; 6. Battery cell;

10. electrode assembly; 11. first pole piece; 111. straight portion; 12. second pole piece; 121. second bending portion; 13. isolating member; 14. bending portion; 141. first bending portion; 142. second bending portion; 15. insulating member; 151. first insulating member; 151a. first main body; 151b. first connecting portion; 152. second insulating member; 152a. second main body; 152b. second connecting portion; 16. adhesive layer;

20. housing; 21. shell; 22. end cap; 30. electrode terminal;

A, winding direction; B, bending area; C, straight area; Z, first direction.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

The term "and/or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character "/" in this application generally indicates that the associated objects before and after are in an "or" relationship.

In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

The term "plurality" used in the present application refers to two or more (including two).

In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium-gold batteries, The present invention relates to a metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, etc., which is not limited in the embodiments of the present application.

A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO ₂ ), lithium nickel oxide (such as LiNiO ₂ ), lithium manganese oxide (such as LiMnO ₂ , LiMn2O ₄ ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (also referred to as NCM ₃₃₃ ), LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also referred to as NCM ₅₂₃ ), LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also referred to as NCM ₂₁₁ ), LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM ₆₂₂ ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), and LiNi _0.8 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM ₈₁₁ )), lithium nickel cobalt aluminum oxide (such as LiNi _0.85 Co _0.15 Al _0.05 O ₂ ) and modified compounds thereof.

In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, or a carbon foam. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or/and deposited in the foamed metal, and the lithium source material is lithium metal and/or a lithium-rich material.

In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

As an example, the negative electrode current collector may be a metal foil, a foamed metal or a composite current collector. For example, as the metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene, It is formed on a substrate such as polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

The liquid electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be selected from ether solvents. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

Among them, the gel electrolyte includes a polymer as the electrolyte skeleton network, with an ionic liquid-lithium Salt.

Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, and the like.

As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphide, germanium argentum sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

As an example, the separator may be disposed continuously and disposed between adjacent positive electrode sheets or negative electrode sheets in a winding manner.

In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in this application.

The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells are accommodated in the case.

In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

When the battery cell is charged, metal ions are released from the positive electrode and embedded in the negative electrode, but a Some abnormal conditions may cause the precipitation of metal ions, resulting in the risk of short circuit between the positive and negative electrodes.

For example, taking a lithium-ion battery cell as an example, due to insufficient lithium embedding space in the negative electrode sheet, too much resistance to lithium ion embedding in the negative electrode sheet, or too fast lithium ion escapes from the positive electrode sheet, the escaped lithium ions cannot be embedded in the negative electrode sheet in equal amounts. The lithium ions that cannot be embedded in the negative electrode sheet can only obtain electrons on the surface of the negative electrode sheet, thereby forming metallic lithium. This is the lithium precipitation phenomenon. Lithium precipitation not only reduces the performance of lithium-ion battery cells and greatly shortens the cycle life, but also limits the fast charging capacity of lithium-ion battery cells. In addition, when lithium precipitation occurs in the battery cell, the precipitated lithium metal is very active and can react with the electrolyte at a relatively low temperature, causing the battery cell's self-heating starting temperature (Tonset) to decrease and the self-heating rate to increase, seriously endangering the safety of the battery cell.

The winding electrode assembly is more prone to lithium deposition in its bending area, and the main reason for the lithium deposition is that the positive and negative electrode sheets located in the bending area need to be bent, and the positive and negative electrode active material layers are prone to stress concentration during the bending process and cause the respective active materials to fall off. Due to the shedding of active materials, especially the shedding of active materials on the negative electrode sheet, the number of lithium embedded sites of the negative electrode active material layer of the negative electrode sheet may be less than the number of lithium ions that can be provided by the positive electrode active material layer of the adjacent positive electrode sheet, thereby causing lithium deposition. When lithium deposition is severe, the released lithium ions can form lithium crystals on the surface of the negative electrode sheet, and the lithium crystals can easily puncture the separator, causing the risk of short circuit between the adjacent positive and negative electrode sheets.

In view of this, an embodiment of the present application provides an electrode assembly, which isolates the positive electrode sheet and the negative electrode sheet by disposing an insulating member in the bending area, thereby reducing the risk of short circuit between the positive and negative electrode sheets and improving the reliability of the battery cell.

The electrode assembly described in the embodiments of the present application is applicable to a battery cell, a battery, and an electrical device using the battery.

The electric device disclosed in the embodiments of the present application can be used for electric devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. The electric device can be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

FIG1 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application.

As shown in FIG1 , a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

The vehicle 1 may further include a controller 3 and a motor 4 , wherein the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

FIG2 is an exploded schematic diagram of a battery provided in some embodiments of the present application. As shown in FIG2 , the battery 2 includes a box body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the box body 5 .

The box 5 is used to accommodate the battery cell 6, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b together define a storage space 5c for accommodating the battery cell 6. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-shaped structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b are connected to each other to form a box 5 with a storage space 5c. The two box parts 5b can also be a hollow structure with one side open, and the open side of the first box part 5a covers the open side of the second box part 5b to form a box 5 with a receiving space 5c. Of course, the first box part 5a and the second box part 5b can be in various shapes, such as a cylinder, a cuboid, etc.

In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box.

In the battery 2, the battery cell 6 can be one or more. If there are more than one battery cell 6, the battery cells 6 can be connected in series, in parallel or in mixed connection. Mixed connection means that the battery cells 6 are both connected in series and in parallel. The battery cells 6 can be directly connected in series, in parallel or in mixed connection, and then the whole formed by the battery cells 6 can be accommodated in the box 5; of course, the battery cells 6 can also be connected in series, in parallel or in mixed connection to form a battery module, and then the battery modules can be connected in series, in parallel or in mixed connection to form a whole, and then accommodated in the box 5.

FIG. 3 is a schematic diagram of an explosion of a battery cell provided in some embodiments of the present application.

The battery cell 6 may be the smallest unit constituting the battery. As shown in FIG. 3 , in some embodiments, the battery cell 6 includes a housing 20 and an electrode assembly 10 , and the electrode assembly 10 is accommodated in the housing 20 .

The housing 20 is a hollow structure, and a space for accommodating the electrode assembly 10 and the electrolyte is formed therein. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a rectangular parallelepiped structure, a rectangular housing can be selected; if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be selected.

In some embodiments, the housing 20 includes a shell 21 and an end cover 22 , the shell 21 has an opening, and the end cover 22 is used to cover the opening.

The housing 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte and other components.

The housing 21 and the end cap 22 may be independent components. For example, an opening may be provided on the housing 21, and the end cap 22 may cover the opening to form an internal cavity of the battery cell 6.

The shell 21 can be in various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application does not impose any special restrictions on this.

The shape of the end cap 22 can be adapted to the shape of the shell 21 to match the shell 21. The material of the end cap 22 can be the same as or different from the material of the shell 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when squeezed and collided, so that the battery cell 6 can have a higher structural strength and the reliability performance can also be improved.

The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be a structure with an opening at one end, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may be a structure with openings at both ends, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

In some embodiments, the battery cell 6 further includes an electrode terminal 30, which is used to connect to the electrode assembly. The component 10 is electrically connected to output or input the electrical energy of the battery cell 6.

The electrode assembly 10 is a component where electrochemical reactions occur in the battery cell 6. One or more electrode assemblies 10 may be contained in the housing 21.

As an example, the electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly 10, and the portions of the positive electrode sheet and the negative electrode sheet not having active materials each constitute a tab. The tab may include a positive tab and a negative tab. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body.

During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs are connected to the electrode terminals 30 to form a current loop.

In some embodiments, there are two electrode terminals 30 and both are disposed on the end cap 22. One electrode terminal 30 is electrically connected to the positive electrode tab, and the other electrode terminal 30 is connected to the negative electrode tab.

Figure 4 is a schematic diagram of an electrode assembly provided in some embodiments of the present application; Figure 5 is a partial cross-sectional schematic diagram of an electrode assembly provided in some embodiments of the present application; Figure 6 is another partial cross-sectional schematic diagram of an electrode assembly provided in some embodiments of the present application; Figure 7 is an enlarged schematic diagram of Figure 6 at the circle frame.

4 to 7, an embodiment of the present application provides an electrode assembly 10, which includes a first pole piece 11, a second pole piece 12, and a separator 13. The first pole piece 11 and the second pole piece 12 have opposite polarities, and the separator 13 is used to separate the first pole piece 11 from the second pole piece 12. The first pole piece 11, the second pole piece 12, and the separator 13 are wound along a winding direction A and form a bending region B.

The electrode assembly 10 may be in various shapes. For example, the electrode assembly 10 may be cylindrical, flat, prism (eg, triangular prism, quadrangular prism or hexagonal prism) or other shapes.

One of the first electrode sheet 11 and the second electrode sheet 12 is a positive electrode sheet, and the other is a negative electrode sheet.

The isolating member 13 may be one or more. For example, two isolating members 13 are provided, and the embodiment of the present application may first stack one isolating member 13, the first pole piece 11, another isolating member 13 and the second pole piece 12 in sequence, and then wind them more than two times to form a winding structure.

The winding direction A may be a direction in which the first pole piece 11 and the second pole piece 12 are wound from the inside to the outside. For example, in FIG4 , the winding direction A is a clockwise direction.

The separator 13 is used to insulate the first pole piece 11 and the second pole piece 12 to reduce the risk of short circuit between the first pole piece 11 and the second pole piece 12. Exemplarily, the separator 13 includes an insulating film having a large number of through micropores, and the micropores are provided to allow metal ions to freely pass through the separator 13.

Optionally, the insulating film has good permeability to lithium ions and basically cannot block the passage of lithium ions. Optionally, the insulating film can be made of at least one of PP (polypropylene) or PE (polyethylene), ethylene-propylene copolymer, polybutylene terephthalate, etc. Optionally, the separator 13 also includes a functional layer disposed on the surface of the insulating film, which can be a mixture layer of ceramic oxide and adhesive.

The bending region B may be a region of the electrode assembly 10 having a bending structure, and the portion of the first pole piece 11 located in the bending region B and the portion of the second pole piece 12 located in the bending region B are both bent. Exemplarily, the portion of the first pole piece 11 located in the bending region B and the portion of the second pole piece 12 located in the bending region B are substantially bent into an arc shape.

The electrode assembly 10 may be a bent region B as a whole. For example, the electrode assembly 10 is cylindrical, and the first electrode sheet 11 is in a bent state as a whole, and the second pole piece 12 is in a bent state as a whole.

Alternatively, only a part of the electrode assembly 10 may be the bending area B. For example, the electrode assembly 10 is flat and includes a straight area C and a bending area B, and the bending area B is connected to the straight area C. The straight area C may be an area of the electrode assembly 10 having a straight structure, and the portion of the first pole piece 11 located in the straight area C and the portion of the second pole piece 12 located in the straight area C are both substantially straight.

In some embodiments, the electrode assembly 10 further includes an insulating member 15 , at least a portion of which is located in the bending region B and between the first pole piece 11 and the second pole piece 12 .

The insulating member 15 may be located entirely in the bending region B or only partially in the bending region B. For example, for an electrode assembly 10 including a straight region C, the insulating member 15 may be located entirely in the bending region B or partially in the bending region B and partially in the straight region C.

The insulating member 15 can be independently disposed between the first pole piece 11 and the second pole piece 12, or can be attached to any surface of the first pole piece 11, the isolating member 13 or the second pole piece 12. The insulating member 15 can be independently disposed between the first pole piece 11 and the second pole piece 12, which means that the insulating member 15 is separately stacked with the first pole piece 11 and the second pole piece 12, respectively, and there is no adhesion or coating relationship between the insulating member 15 and the first pole piece 11, and between the insulating member 15 and the second pole piece 12. Attachment means attaching and connecting, for example, the insulating member 15 is attached to the first pole piece 11 or the second pole piece 12 by adhesion, coating or other means.

The insulating member 15 may have a microporous structure, and some ions may pass through the insulating member 15 and be reciprocatedly deintercalated between the first electrode sheet 11 and the second electrode sheet 12. Alternatively, the insulating member 15 may not have a microporous structure, which may be used to block at least some ions released from the positive electrode sheet from being embedded in the negative electrode sheet in the bending region B; when the negative electrode active material of the negative electrode sheet in the bending region B falls off, the barrier layer may block at least some ions released from the positive electrode sheet, thereby reducing the risk of ion precipitation.

The insulating member 15 may be a single-layer structure or a multi-layer structure.

In the embodiment of the present application, an insulating member 15 is provided in the bending region B. Even if ion precipitation occurs in the bending region B, such as lithium ion precipitation, the insulating member 15 can block the lithium dendrites generated by the lithium precipitation to a certain extent, thereby reducing the risk of conduction between the first pole piece 11 and the second pole piece 12, and improving the reliability of the electrode assembly 10 and the battery cell 6.

In some embodiments, the first pole piece 11 and the second pole piece 12 both include a plurality of bending portions 14 located in the bending region B, and at least one bending portion 14 of the first pole piece 11 is a first bending portion 141. At least one side of the first bending portion 141 is provided with an insulating member 15 adjacent thereto.

The bent portion 14 of the first pole piece 11 and the bent portion 14 of the second pole piece 12 are both bent.

Exemplarily, in the bending area B, the bending portions 14 of the first pole piece 11 and the bending portions 14 of the second pole piece 12 are arranged alternately, that is, in the bending area B, they are arranged in the order of a bending portion 14 of the second pole piece 12, a bending portion 14 of the first pole piece 11, a bending portion 14 of the second pole piece 12...

The first bending portion 141 may be the bending portion 14 of the first pole piece 11 adjacent to the insulating member 15 . The first bending portion 141 being adjacent to the insulating member 15 means that the second pole piece 12 and the insulating member 13 are not disposed between the first bending portion 141 and the insulating member 15 .

In the embodiment of the present application, the insulating member 15 may be disposed on the inner side of the first bending portion 141 , the insulating member 15 may be disposed on the outer side of the first bending portion 141 , or the insulating member 15 may be disposed on both the inner and outer sides of the first bending portion 141 .

The first bending portion 141 may be one or more. For example, in the first pole piece 11, all The bending portions 14 are all first bending portions 141 , or part of the bending portions 14 may be the first bending portions 141 .

In the embodiment of the present application, the insulating member 15 can separate the first bent portion 141 from the second pole piece 12, reduce the risk of the first bent portion 141 and the second pole piece 12 being connected, and improve reliability. The insulating member 15 can also shield the current collector exposed outside the first bent portion 141 and the dropped active material when the first bent portion 141 is broken, reducing the risk of short circuit.

In some embodiments, the electrode assembly 10 further includes a straight region C connected to the bent region B. Both ends of the insulating member 15 along the winding direction A are located in the straight region C.

Exemplarily, the surface of the first pole piece 11 located in the straight region C is substantially planar, and the surface of the second pole piece 12 located in the straight region C is substantially planar.

The embodiment of the present application allows the insulating member 15 to pass through the bending area B as a whole to insulate the first bending portion 141 from the second pole piece 12, and reduces the possibility that the end of the insulating member 15 along the winding direction A is located in the bending area B due to assembly errors, thereby reducing the risk of conduction between the first bending portion 141 and the second pole piece 12 and improving reliability.

In some embodiments, the electrode assembly 10 includes two bending regions B, and the two bending regions B are respectively connected to two ends of the straight region C.

In some embodiments, the first electrode 11 is a positive electrode, and the second electrode 12 is a negative electrode. At least one bend 14 of the second electrode 12 is a second bend 142 adjacent to the first bend 141 and located inside the first bend 141. The insulating member 15 separates the first bend 141 from the second bend 142.

In the second pole piece 12, there may be one or more second bending portions 142. In the second pole piece 12, all bending portions 14 may be second bending portions 142, or some bending portions 14 may be second bending portions 142. Exemplarily, the number of second bending portions 142 is the same as the number of first bending portions 141.

The second bend 142 is located inside the first bend 141. The curvature of the second bend 142 is greater than that of the first bend 141. The second bend 142 is more likely to generate stress concentration during the bending process and cause the negative active material to fall off. Due to the falling off of the negative active material, the number of ion embedding sites of the negative active material layer of the second bend 142 may be less than the number of ions provided by the positive active material layer of the first bend 141, thereby causing ion precipitation. The negative active material layer of the second bend 142 is in a bent state. When the negative active material layer of the second bend 142 is vibrated or squeezed, the negative active material is more likely to fall off.

In the embodiment of the present application, when ion precipitation (such as lithium ion precipitation) occurs in the second bending portion 142, the insulating member 15 can also block the lithium dendrites generated by the lithium precipitation to a certain extent, thereby reducing the risk of lithium dendrites connecting the first bending portion 141 and the second bending portion 142, and improving the reliability of the electrode assembly 10 and the battery cell 6.

In some embodiments, at least the innermost bent portion 14 of the first pole piece 11 is a first bent portion 141 , and at least the innermost bent portion 14 of the second pole piece 12 is a second bent portion 142 .

The innermost bending portion 14 of the first pole piece 11 has the largest bending degree, that is, the positive electrode active material at the innermost bending portion 14 of the first pole piece 11 has the most serious shedding phenomenon; the innermost bending portion 14 of the second pole piece 12 has the largest bending degree, that is, the negative electrode active material at the innermost bending portion 14 of the second pole piece 12 has the most serious shedding phenomenon, and the innermost bending portion 14 of the second pole piece 12 is most prone to ion precipitation.

In the embodiment of the present application, at least the innermost bend portion 14 of the first pole piece 11 is set as the first bend portion 141, and at least the innermost bend portion 14 of the second pole piece 12 is set as the second bend portion 142. This can reduce the risk of conduction between the two innermost bend portions 14 of the bending area B and improve reliability.

The utilization rate of the active material of the positive electrode sheet can be improved by arranging the bent portion 14 of the negative electrode sheet at the innermost side.

In some embodiments, the tensile strength of the insulating member 15 is 60 MPa-120 MPa. Optionally, the tensile strength of the insulating member 15 is 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 10 MPa or 120 MPa.

In the embodiment of the present application, the insulating member 15 has a high tensile strength. During the bending process of the insulating member 15 and the hot pressing process of the electrode assembly 10, the insulating member 15 is not easy to crack, thereby reducing the possibility of dendrites (such as lithium dendrites) formed by ion precipitation passing through the insulating member 15 through the microcracks of the insulating member 15, thereby reducing the risk of short circuit.

In some embodiments, the tensile strength of the insulating member 15 is 80 MPa-120 MPa. The embodiment of the present application can further reduce the risk of cracking of the insulating member 15 .

In some embodiments, the insulating member 15 is non-sticky. The non-stickiness of the insulating member 15 means that the insulating member 15 is non-sticky during the production, transportation and normal use of the battery cell 6 .

The insulating member 15 is non-sticky to reduce the risk of the insulating member 15 adhering to the first bending portion 141 during the hot pressing process.

Compared with the solution in which the insulating member 15 is sticky, the embodiment of the present application can also reduce the risk of ion precipitation and improve the reliability of the battery cell 6. Specifically, the electrode assembly 10 usually needs to be hot-pressed during the molding process. During hot pressing, if the insulating member 15 is sticky, the insulating member 15 may partially melt into a colloid and flow around. The colloid may pass through the micropores of the separator 13 and adhere to the separator 13 and the surface of the second pole piece 12. It is difficult for ions to embed into the area covered by the glue layer of the second pole piece 12, so that the ions are enriched at the edge of the glue layer on the second pole piece 12, causing the risk of ion precipitation. The insulating member 15 of the embodiment of the present application is not sticky, which can reduce the risk of ion precipitation.

In some embodiments, the material of the insulating member 15 includes olefin polymer. Olefin polymer is generally non-sticky and has high tensile strength and impact resistance. When the electrode assembly 10 is hot-pressed, the insulating member 15 is not easy to crack, thereby reducing the possibility of lithium dendrites passing through the insulating member 15 through microcracks of the insulating member 15 and reducing the risk of short circuit.

In some embodiments, the insulating member 15 is made of olefin polymer. Olefin polymer is non-sticky and is not easily adhered to the separator 13 and the second pole piece 12 during hot pressing, thereby reducing the risk of ion precipitation and improving reliability.

In some embodiments, the olefin polymer comprises one of polyethylene, polypropylene, or polyimide. Optionally, the polypropylene comprises biaxially oriented polypropylene.

These materials have high tensile strength and impact resistance and are not prone to cracking during the hot pressing process of the electrode assembly 10 .

In some embodiments, the first electrode 11 is a positive electrode, and the second electrode 12 is a negative electrode. The insulating member 15 is used to prevent at least a portion of ions escaped from the first electrode 11 from being embedded in the second electrode 12.

During charging, the ions released from the positive active material layer of the positive electrode sheet are at least partially blocked by the insulating member 15, so that the ions blocked by the insulating member 15 cannot be embedded in the negative active material layer of the negative electrode sheet in the bending area B, thereby reducing the risk of ion precipitation when the negative active material of the negative electrode sheet falls off. Although the negative electrode sheet has fewer ion embedding sites due to the shedding of the negative active material, the insulating member 15 blocks at least a portion of the ions released from the positive electrode sheet, so the phenomenon of ion precipitation can be reduced.

Optionally, the tensile strength of the insulating member 15 is 60 MPa-120 MPa, and the insulating member 15 is not easy to crack during the production and use of the electrode assembly 10, thereby reducing the risk of ions being embedded into the negative electrode sheet through microcracks of the insulating member 15. risk, thereby reducing ion precipitation.

Optionally, the insulating member 15 is attached to the positive electrode sheet. After the lithium dendrites appearing on the negative electrode sheet pierce the separator 13, the insulating member 15 is in close contact with the positive electrode sheet and is not easily extended even under the force of the lithium dendrites, thereby reducing the risk of short circuit caused by the lithium dendrites contacting the positive electrode sheet.

In some embodiments, the thickness of the insulating member 15 is 2 μm-200 μm. Optionally, the thickness of the insulating member 15 is 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm or 200 μm.

In some embodiments, the thickness of the insulating member 15 is 3 μm-100 μm. Optionally, the thickness of the insulating member 15 is 2 μm-20 μm.

The embodiment of the present application can balance the weight of the insulating member 15 and the protective effect of the insulating member 15 .

In some embodiments, the insulating member 15 is independently disposed on the first bending portion 141 to facilitate installation of the insulating member 15. The insulating member 15 is independently disposed on the first bending portion 141, which can reduce the impact on the insulating member 15 when the first bending portion 141 expands and deforms, reduce the risk of stretching and cracking of the insulating member 15, and improve the reliability of the insulating member 15.

In some embodiments, at least one end of the insulating member 15 along the first direction Z extends beyond the first bending portion 141 , and the first direction Z is perpendicular to the winding direction A.

In some embodiments, both ends of the insulating member 15 along the first direction Z extend beyond the first bending portion 141 , and the first direction Z is perpendicular to the winding direction A.

One end of the insulating member 15 in the first direction Z is located further outward than one end of the first bending portion 141 in the first direction Z, and the other end of the insulating member 15 in the first direction Z is located further outward than the other end of the first bending portion 141 in the first direction Z.

The end of the insulating member 15 along the first direction Z may extend beyond the second bending portion 142 , or may not extend beyond the second bending portion 142 .

When the battery cell 6 is subjected to external impact, both ends of the insulating member 15 along the first direction Z can play a supporting role, thereby reducing the vibration amplitude of the first bending portion 141, reducing the impact force on the first bending portion 141, reducing the shedding of active materials, and improving the cycle performance of the battery cell 6.

In some embodiments, in the first direction Z, at least one end of the insulating member 15 extends beyond the first bending portion by 3 mm to 6 mm. Optionally, in the first direction Z, both ends of the insulating member 15 extend beyond the first bending portion by 3 mm to 6 mm.

In some embodiments, both sides of the first bending portion 141 are provided with insulating members 15 adjacent thereto.

The insulating members 15 located on both sides of the first bending portion 141 may be connected or independent of each other.

The insulating member 15 can separate the two side surfaces of the first bent portion 141 from the second pole piece 12 , thereby further reducing the risk of conduction between the first bent portion 141 and the second pole piece 12 and improving the reliability of the electrode assembly 10 and the battery cell 6 .

In some embodiments, the insulating members 15 located on both sides of the first bending portion 141 are respectively a first insulating member 151 and a second insulating member 152. Two ends of the first insulating member 151 along the first direction Z are connected to two ends of the second insulating member 152 along the first direction Z respectively.

The first insulating member 151 and the second insulating member 152 may be connected as one piece; alternatively, the first insulating member 151 and the second insulating member 152 may be formed separately, and the two may be connected as one piece by bonding, welding, clamping or other means.

The first insulating member 151 and the second insulating member 152 are connected so that the whole formed by the two can be sleeved on the first On the pole piece 11, when the battery cell 6 is subjected to external impact, the movement of the first insulating member 151 and the second insulating member 152 relative to the first bending portion 141 is reduced, the insulation reliability of the first insulating member 151 and the second insulating member 152 is improved, and the short circuit risk is reduced.

In addition, the first insulating member 151 and the second insulating member 152 are mounted on the first pole piece 11 by being connected to each other, so that the insulating member 15 and the first bending portion 141 can be independently arranged.

In some embodiments, bent portions 14 of the negative electrode sheet are provided on both sides of the first bent portion 141 , and the first insulating member 151 and the second insulating member 152 can completely separate the first bent portion 141 from the negative electrode sheet to reduce the risk of short circuit.

In some embodiments, the electrode assembly 10 further includes a glue layer 16 , and at least one end of the first insulating member 151 along the first direction Z is connected to the second insulating member 152 through the glue layer 16 .

One end of the first insulating member 151 along the first direction Z can be connected to the second insulating member 152 through the adhesive layer 16; the other end of the first insulating member 151 along the first direction Z can be connected to the second insulating member 152 by bonding, welding, clamping, integral connection or other methods.

By providing the adhesive layer 16 , the first insulating member 151 and the second insulating member 152 can be easily bonded.

In some embodiments, the adhesive layer 16 includes acrylic resin and/or polyolefin resin. Both acrylic resin and polyolefin resin are adhesive and can firmly bond the first insulating member 151 and the second insulating member 152 .

In some embodiments, the acrylic resin includes one or more of acrylic acid-methacrylic acid copolymer, acrylic acid-butenoic acid copolymer, acrylic acid-itaconic acid copolymer, acrylic acid-maleic acid copolymer, acrylic acid-methyl methacrylate copolymer, acrylic acid-ethyl methacrylate copolymer, acrylic acid-n-butyl methacrylate copolymer, and acrylic acid-isobutyl methacrylate copolymer.

The above materials have good chemical stability and electrochemical stability and are not easily soluble in electrolyte.

In some embodiments, the polyolefin resin includes any one or more of polypropylene, polyethylene, polybutadiene rubber, ethylene-propylene acetate copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, maleic anhydride modified polyolefin and polybutadiene-acrylonitrile, styrene-maleic anhydride copolymer. Adding anhydride modified polar functional groups can significantly improve the adhesion.

The above materials have good chemical stability and electrochemical stability and are not easily soluble in electrolyte.

In some embodiments, the adhesive layer 16 includes a tackifier, which can increase the tackiness of the adhesive layer 16 .

Exemplarily, the insulating member 15 does not contain an adhesion promoter.

In some embodiments, the tackifier may include a tackifying resin, such as a maleic anhydride modified polypropylene resin.

In some embodiments, the weight percentage of the tackifier in the adhesive layer 16 is 3%-20%. Optionally, the weight percentage of the tackifier in the adhesive layer 16 is 5%-10%.

In some embodiments, in the thickness direction of the first bending portion 141 , the portion of the first insulating member 151 overlapping the first bending portion 141 is not provided with an adhesive layer, and the portion of the second insulating member 152 overlapping the first bending portion 141 is not provided with an adhesive layer.

In some embodiments, the first insulating member 151 includes a first main body portion 151a and a first connecting portion 151b, wherein the first connecting portion 151b extends from an end portion of the first main body portion 151a along the first direction Z. The second insulating member 152 includes a second main body portion 152a and a second connecting portion 152b, wherein the second connecting portion 152b extends from an end portion of the second main body portion 152a along the first direction Z. The first bending portion 141 is located between the first main body portion 151a and the second main body portion 152a, and the adhesive layer 16 is bonded between the first connecting portion 151b and the second connecting portion 152b.

Exemplarily, the first connection portion 151b may be the portion of the first insulating member 151 that extends beyond the first bending portion 141 in the first direction Z and is directly bonded to the adhesive layer 16, and the first connection portion 151b may be the portion of the second insulating member 152 that extends beyond the first bending portion 141 in the first direction Z and is directly bonded to the adhesive layer 16.

The first insulating member 151 may be provided with the first connection portion 151b at only one end along the first direction Z, or at both ends along the first direction Z. The second insulating member 152 may be provided with the second connection portion 152b at only one end along the first direction Z, or at both ends along the first direction Z.

The first main body 151a and the second main body 152a can cover the first bent portion 141 from both sides, thereby isolating the two side surfaces of the first bent portion 141 from the second pole piece 12, thereby further reducing the risk of conduction between the first bent portion 141 and the second pole piece 12, and improving the reliability of the electrode assembly 10 and the battery cell 6. The first connecting portion 151b and the second connecting portion 152b can be connected by the adhesive layer 16, so as to reduce the movement of the first main body 151a and the second main body 152a relative to the first bent portion 141 when the battery cell 6 is subjected to external impact, thereby improving the insulation reliability and reducing the risk of short circuit.

In some embodiments, no adhesive layer is disposed between the first main body portion 151 a and the first bending portion 141 , and no adhesive layer is disposed between the second main body portion 152 a and the first bending portion 141 .

The embodiment of the present application can save the amount of adhesive layer 16 and improve the energy density of the battery. The first main body 151a can be independently provided with the first bending portion 141, and the second main body 152a can be independently provided with the second bending portion 142, which can reduce the impact on the insulating member 15 when the first bending portion 141 is deformed, reduce the risk of stretching and cracking of the insulating member 15, and improve the reliability of the insulating member 15.

In addition, compared with the solution of bonding the first main body portion 151 a and the first bending portion 141 with an adhesive layer, the embodiment of the present application can also reduce the risk of ion precipitation and improve the reliability of the battery cell 6 .

Specifically, the electrode assembly 10 usually needs to undergo hot pressing during the molding process. During hot pressing, the glue layer may overflow from the edge of the first main body 151a along the winding direction A; the overflowed glue layer may pass through the micropores of the isolation member 13 and adhere to the surfaces of the isolation member 13 and the second pole piece 12, making it difficult for ions to embed into the area of the second pole piece 12 covered by the glue layer, thereby enriching the ions at the edge of the glue layer on the second pole piece 12, causing the risk of ion precipitation.

Using an adhesive layer to bond the second main body portion 152 a and the first bent portion 141 may also cause the risk of ion precipitation.

In the embodiment of the present application, no glue layer is set between the first main body 151a and the first bending portion 141, and no glue layer is set between the second main body 152a and the first bending portion 141. During hot pressing, the first main body 151a and the second main body 152a are not easily squeezed by the glue layer 16, thereby reducing overflow of the glue layer 16, reducing the risk of ion precipitation, and improving reliability.

In some embodiments, the end of the first main body 151a along the winding direction A is located in the straight region C. The first pole piece 11 further includes a straight portion 111 connected to the first bending portion 141 and located in the straight region C. No glue layer is disposed between the straight portion 111 and the first main body 151a.

The end of the second body portion 152 a along the winding direction A is located in the straight region C. No adhesive layer is disposed between the straight portion 111 and the second body portion 152 a.

When the electrode assembly 10 is hot pressed, the straight region C is the main pressure region. Providing a glue layer between the first main body 151a and the straight portion 111 and between the second main body 152a and the straight portion 111 makes it easier for glue overflow to occur.

In the embodiment of the present application, no adhesive layer is provided between the straight portion 111 and the first main body portion 151a. No glue layer is provided between 152a and the straight portion 111 to reduce glue overflow and lower the risk of ion precipitation.

In some embodiments, the first main body portion 151 a may be a portion of the first insulating member 151 not covered by the adhesive layer 16 , and the second main body portion 152 a may be a portion of the second insulating member 152 not covered by the adhesive layer 16 .

In some embodiments, the first insulating member 151 includes two first connecting portions 151b, which extend from two ends of the first main body portion 151a along the first direction Z. The second insulating member 152 includes two second connecting portions 152b, which extend from two ends of the second main body portion 152a along the first direction Z. The two first connecting portions 151b are respectively bonded to the two second connecting portions 152b through the adhesive layer 16.

The first insulating member 151 and the second insulating member 152 can be formed independently, and both can be attached to the first pole piece 11 from two layers, which can simplify the assembly process.

In some embodiments, before assembly, both ends of the first insulating member 151 and both ends of the second insulating member 152 are coated with colloid, and the colloid on the first insulating member 151 and the colloid on the second insulating member 152 are bonded, cured, and form an adhesive layer 16. In other embodiments, before assembly, only the colloid is coated on both ends of the first insulating member 151, and then the colloid on the first insulating member 151 is bonded to the second insulating member 152, and the colloid is cured to form an adhesive layer 16.

In some embodiments, in the first direction Z, both ends of the first insulating member 151 extend beyond the first bending portion by 3 mm to 6 mm, and both ends of the first insulating member 151 extend beyond the first bending portion by 3 mm to 6 mm. In the embodiment of the present application, the size of the first insulating member 151 and the size of the second insulating member 152 can be reduced to improve the energy density, provided that the bonding area between the first connecting portion 151b and the second connecting portion 152b meets the requirements.

FIG8 is a schematic partial cross-sectional view of an electrode assembly provided in some other embodiments of the present application; FIG9 is an enlarged schematic view of the circle frame of FIG8 .

As shown in Figures 8 and 9, in some embodiments, the first insulating member 151 includes a first connecting portion 151b, and the second insulating member 152 includes a second connecting portion 152b. One end of the first body portion 151a away from the first connecting portion 151b is integrally connected to one end of the second body portion 152a away from the second connecting portion 152b.

For example, the first insulating member 151 and the second insulating member 152 may be formed by folding one insulating plate in half.

The embodiment of the present application can reduce the amount of adhesive layer 16 used, reduce the maximum size of the first insulating member 151 and the second insulating member 152 along the first direction Z, improve the energy density, and increase the connection strength between the first insulating member 151 and the second insulating member 152.

According to some embodiments of the present application, the present application further provides a battery cell, comprising a housing and an electrode assembly provided by any of the above embodiments, wherein the electrode assembly is accommodated in the housing.

According to some embodiments of the present application, the present application also provides a battery, comprising a plurality of battery cells according to any one of the above embodiments.

According to some embodiments of the present application, the present application further provides an electric device, comprising a battery in any of the above embodiments, the battery is used to provide electric energy to the electric device. The electric device can be any of the above-mentioned devices or systems using the battery.

According to some embodiments of the present application, referring to FIGS. 4 to 7 , embodiments of the present application provide an electrode assembly 10 , which includes a first pole piece 11 , a second pole piece 12 , a separator 13 and an insulating member 15 .

The first pole piece 11 is a positive pole piece, and the second pole piece 12 is a negative pole piece. The separator 13 is used to separate the first pole piece 11 from the second pole piece 12. The first pole piece 11, the second pole piece 12 and the separator 13 are wound along a winding direction A to form a bending area B and a straight area C.

The first pole piece 11 and the second pole piece 12 both include a plurality of bent portions 14 located in the bent region B. In the bent region B, the innermost bent portion 14 of the first pole piece 11 is a first bent portion 141, and both sides of the first bent portion 141 are provided with insulating members 15 adjacent thereto. One bent portion 14 of the second pole piece 12 is a second bent portion 142 adjacent to and located inside the first bent portion 141.

The insulating member 15 is non-sticky, and the tensile strength of the insulating member 15 is 80 MPa-120 MPa. Both ends of the insulating member 15 along the first direction Z extend beyond the first bending portion 141 , and the first direction Z is perpendicular to the winding direction A.

The insulating members 15 located on both sides of the first bending portion 141 are respectively the first insulating member 151 and the second insulating member 152. The first insulating member 151 includes a first main body 151a and two first connecting portions 151b, and the two first connecting portions 151b extend from the ends of the first main body 151a along the first direction Z respectively. The second insulating member 152 includes a second main body 152a and two second connecting portions 152b, and the two second connecting portions 152b extend from the ends of the second main body 152a along the first direction Z respectively. The first bending portion 141 is located between the first main body 151a and the second main body 152a, and the two first connecting portions 151b are respectively bonded to the two second connecting portions 152b through the adhesive layer 16. No adhesive layer is provided on the surface of the first main body 151a, and no adhesive layer is provided on the surface of the second main body 152a.

Two ends of the first insulating member 151 along the first direction Z are respectively connected to two ends of the second insulating member 152 along the first direction Z through the adhesive layer 16 .

Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (24)

An electrode assembly, comprising a first pole piece, a second pole piece and a separator, wherein the first pole piece and the second pole piece have opposite polarities, the separator is used to separate the first pole piece and the second pole piece, and the first pole piece, the second pole piece and the separator are wound along a winding direction to form a bending area; The electrode assembly further includes an insulating member, at least a portion of which is located in the bending region and between the first pole piece and the second pole piece. The electrode assembly according to claim 1, wherein the first pole piece and the second pole piece each include a plurality of bending portions located in the bending region, and at least one of the bending portions of the first pole piece is a first bending portion; At least one side of the first bending portion is provided with the insulating member adjacent thereto. The electrode assembly according to claim 2, further comprising a straight region connected to the bent region; Both ends of the insulating member along the winding direction are located in the straight area. The electrode assembly according to claim 2 or 3, wherein the first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet; At least one bending portion of the second pole piece is a second bending portion adjacent to the first bending portion and located inside the first bending portion; The insulating member separates the first bending portion from the second bending portion. The electrode assembly according to claim 4, wherein at least the innermost bend in the first pole piece is the first bend, and at least the innermost bend in the second pole piece is the second bend. The electrode assembly according to any one of claims 2 to 5, wherein the insulating member is independently arranged on the first bending portion. The electrode assembly according to any one of claims 2 to 6, wherein both ends of the insulating member along a first direction extend beyond the first bending portion, and the first direction is perpendicular to the winding direction. The electrode assembly according to claim 7, wherein the insulating member adjacent to the first bending portion is provided on both sides of the first bending portion. The electrode assembly according to claim 8, wherein the insulating members located on both sides of the first bending portion are respectively a first insulating member and a second insulating member; Two ends of the first insulating member along the first direction are respectively connected to two ends of the second insulating member along the first direction. The electrode assembly according to claim 9, further comprising a glue layer, and at least one end of the first insulating member along the first direction is connected to the second insulating member through the glue layer. The electrode assembly according to claim 10, wherein the first insulating member comprises a first main body portion and a first connecting portion, the first connecting portion extending from an end portion of the first main body portion along the first direction; The second insulating member includes a second main body portion and a second connecting portion, wherein the second connecting portion extends from an end portion of the second main body portion along the first direction; The first bending portion is located between the first main body portion and the second main body portion, and the adhesive layer is bonded between the first connecting portion and the second connecting portion. The electrode assembly according to claim 11, wherein the glue layer is not provided between the first main body and the first bending portion, and the glue layer is not provided between the second main body and the first bending portion. The electrode assembly according to claim 11 or 12, wherein the first insulating member comprises two first connecting portions, the two first connecting portions respectively extending from two ends of the first main body along the first direction; the second insulating member comprises two second connecting portions, the two second connecting portions respectively extending from two ends of the second main body along the first direction; The two first connection parts are respectively bonded to the two second connection parts through the adhesive layer. The electrode assembly according to claim 11 or 12, wherein the first insulating member includes one first connecting portion, and the second insulating member includes one second connecting portion; One end of the first main body away from the first connecting portion is integrally connected with one end of the second main body away from the second connecting portion. The electrode assembly according to any one of claims 10 to 14, wherein the glue layer comprises acrylic resin and/or polyolefin resin. The electrode assembly according to claim 15, wherein: The acrylic resin includes one or more of acrylic acid-methacrylic acid copolymer, acrylic acid-butenoic acid copolymer, acrylic acid-itaconic acid copolymer, acrylic acid-maleic acid copolymer, acrylic acid-methyl methacrylate copolymer, acrylic acid-ethyl methacrylate copolymer, acrylic acid-n-butyl methacrylate copolymer and acrylic acid-isobutyl methacrylate copolymer; The polyolefin resin includes any one or more of polypropylene, polyethylene, polybutadiene rubber, ethylene-propylene acetate copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, maleic anhydride modified polyolefin, polybutadiene-acrylonitrile, and styrene-maleic anhydride copolymer. The electrode assembly according to any one of claims 1 to 16, wherein the material of the insulating member comprises an olefin polymer. The electrode assembly of claim 17, wherein the olefin polymer comprises one of polyethylene, polypropylene, or polyimide. The electrode assembly according to any one of claims 1 to 18, wherein the tensile strength of the insulating member is 60 MPa to 120 MPa. The electrode assembly according to claim 19, wherein the tensile strength of the insulating member is 80 MPa-120 MPa. The electrode assembly according to any one of claims 1 to 20, wherein the first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet; The insulating member is used to prevent at least a portion of ions escaped from the first pole piece from being embedded in the second pole piece. A battery cell, comprising: shell; The electrode assembly according to any one of claims 1-21 is accommodated in the shell. A battery comprising a plurality of battery cells according to claim 22. An electrical device comprises the battery according to claim 23, wherein the battery is used to provide electrical energy.