CN118676535A

CN118676535A - Separator, electrode assembly, battery and electricity utilization device

Info

Publication number: CN118676535A
Application number: CN202410733121.0A
Authority: CN
Inventors: 杨丽; 张薇; 程进; 李宇航; 陈东
Original assignee: Dongfeng Motor Group Co Ltd
Current assignee: Dongfeng Motor Group Co Ltd
Priority date: 2024-06-07
Filing date: 2024-06-07
Publication date: 2024-09-20
Also published as: WO2025251459A1

Abstract

The application relates to a diaphragm, an electrode assembly, a battery and an electric device, belonging to the technical field of secondary batteries; the membrane comprises a base membrane and a coating, wherein the coating is attached to at least part of the region of the base membrane, the base membrane comprises a first base membrane, a bonding layer and a second base membrane, the bonding layer is arranged between the first base membrane and the second base membrane, the first base membrane is a cellulose membrane, and the second base membrane is a polymer membrane; by compounding the cellulose membrane and the polymer membrane, the membrane has the characteristics of good thermal stability and high tensile strength by utilizing the high heat resistance stability of the cellulose membrane and the high tensile strength of the polymer membrane, and the problem of poor thermal stability of the membrane is solved.

Description

Separator, electrode assembly, battery and electricity utilization device

Technical Field

The application relates to the technical field of secondary batteries, in particular to a diaphragm, an electrode assembly, a battery and an electric device.

Background

The separator is used as one of four key materials of the lithium battery, and has the main effects of separating the positive electrode from the negative electrode, preventing the short circuit caused by the contact of the two electrodes by only limiting electrolyte ions, determining the interface structure, internal resistance and the like of the battery, directly influencing the characteristics of the battery such as capacity (energy density), cycle (service life), safety and the like, and having an important effect on improving the comprehensive performance of the battery. The current commercial separator materials are mainly Polyethylene (PE) and polypropylene (PP) microporous films, which are respectively melted at the temperature range of 125-135 ℃ and 160-165 ℃, have poor thermal stability, and form internal short circuit to cause severe combustion or explosion of the battery. In addition, the organic solvent has inflammability and high corrosiveness, and meanwhile, has poor oxidation resistance, can not solve the problem of lithium dendrite, and is easy to cause short circuit of the battery. Therefore, the conventional lithium battery has a thermal runaway risk, and the use of high-capacity electrode materials such as high-voltage positive electrodes, lithium metal negative electrodes and the like is limited.

Under the higher energy density and safety requirements, the diaphragm and electrolyte system of the traditional battery is replaced by a high-safety diaphragm (such as a coating diaphragm or a solid electrolyte membrane) by adopting the solid battery, so that the safety of the battery can be ensured, and meanwhile, the high-energy density can be realized by being compatible with a high-capacity anode and a high-capacity cathode. The functional coating is often adopted for diaphragm modification, for example, the ceramic coating material has high strength, so that the thermal stability and mechanical strength of the diaphragm can be improved, but the problems of high material density and poor ion conductivity exist, and the energy density and performance of the battery are affected; inorganic solid state electrolytes including lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide coating materials have high ionic conductivity, but complex and expensive manufacturing methods limit their applicability.

For example, in the prior art, a gravure roll coating technology is proposed, a macromolecular ionic polyurethane type amphiphilic polymer is selected as a dispersing agent, ceramic particles are coated by the dispersing agent, the cohesiveness of a ceramic coating is enhanced, the using amount of a binder is reduced, and single-sided ceramic (alumina) coating is performed on a PP membrane, so that an alumina ceramic coating membrane with a total thickness of 16 μm is obtained. In this scheme, although the amount of binder is reduced, the coating used is alumina ceramic having little ion conduction, and is a single-sided coating, and the effect on ion conductivity and thermal stability is not ideal.

It has also been proposed to perform multi-layer composite coating by dip coating, gravure coating, dip and gravure combined coating, wherein the coating slurry is one or more powders of aluminum oxide, zirconium dioxide, silicon dioxide, PVDF and PTFE, the base film is one of PE, PP, PMIA and nonwoven fabric, and the thickness is about 20 μm. In the scheme, a multi-coating is adopted for modifying the base film, but the adopted coating is one or more than two of aluminum oxide, zirconium dioxide, silicon dioxide, PVDF and PTFE powder. Still, there is no excellent ionic conductivity, which results in poor low-temperature electrochemical performance of the battery.

It has also been proposed to prepare a single-sided or double-sided coated membrane on a base membrane by compounding an aramid high temperature resistant binder with an inorganic ceramic or glass fiber, the inorganic ceramic being any one or more of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, barium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide, boehmite; the base film is any one of PE membrane, PP/PE/PP membrane, PET non-woven fabric and PBT non-woven fabric. The coating in the scheme is any one or more of aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, barium oxide, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide and boehmite; high strength oxide materials such as aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, barium oxide, boehmite, etc. are used to modify the membrane to increase the mechanical strength of the membrane, to physically inhibit dendrite growth and to hinder dendrite penetration of the membrane. However, the materials often block the holes of the diaphragm to prevent lithium ion transmission. In addition, the greater density of these materials can significantly increase the separator mass and volume, thereby reducing the energy density of the lithium metal battery. The polyolefin diaphragm is modified by a lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide and other fast ion conductors, and in the battery cycle, the composite diaphragm can autonomously and uniformly carry out lithium ion, so that uniform lithium deposition is realized. However, complex and expensive preparation methods limit the applicability.

It has also been proposed to prepare a composite sol using an inorganic solid electrolyte, a polymer, a lithium salt, and an additive, cast and bake it on a tetrafluoroethylene plate to prepare a self-supporting organic-inorganic composite electrolyte membrane. The inorganic solid electrolyte comprises one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum titanium oxide and lithium lanthanum zirconium oxide; the polymer comprises one or more of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polycyanoacrylate, polyacrylate and polyimide; the lithium salt comprises one or more of lithium bis (fluorosulfonyl) imide, lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium bis (trifluoromethanesulfonyl) imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, lithium nitrate and lithium fluoride. The solution belongs to a self-supporting solid electrolyte membrane, which is prepared by compounding oxide electrolyte, lithium salt and polymer to prepare sol and then casting the sol, and can theoretically improve the ionic conductivity, however, the ionic conductivity in the patent is not obviously improved, and the electrolyte membrane prepared by the method is thicker (more than 25 mu m) and lower in tensile strength (less than 10 MPa), so that the realization of a high-energy density and high-safety battery is not facilitated.

Disclosure of Invention

The application provides a diaphragm, an electrode assembly, a battery and an electric device, which are used for solving the problem of poor thermal stability of the diaphragm.

In a first aspect, the present application provides a separator comprising a base film and a coating layer attached to at least a partial region of the base film, the base film comprising a first base film, an adhesive layer, and a second base film, the adhesive layer being disposed between the first base film and the second base film, the first base film being a cellulosic separator, the second base film being a polymeric separator.

As an alternative embodiment, the components of the cellulose membrane include at least one of cellulose fibers and heat-resistant polyphenylene sulfide fibers; and/or

The composition of the polymeric separator comprises polyethylene.

As an alternative embodiment, the composition of the tie layer comprises a (polyvinylidene fluoride-hexafluoropropylene) copolymer.

As an alternative embodiment, the composition of the coating comprises a functional material, a binder and an auxiliary agent, wherein the functional material comprises a MOF-based material and/or an oxide electrolyte material.

As an alternative embodiment, the MOF-based material includes at least one of ZIF-8, ZIF-67, MOF-199, MOF-74, and UIO-66; and/or

The oxide electrolyte material includes at least one of lithium aluminum titanium phosphate and lithium lanthanum zirconium oxide.

As an alternative embodiment, the functional material has a particle size of 0.3 μm to 3 μm.

As an alternative embodiment, the binder includes at least two binders.

As an alternative embodiment, the binder includes a first binder, a second binder and a third binder, the first binder is an acrylic acid derivative multipolymer, the second binder is a water-resistant binder, and the third binder is a heat-resistant binder.

As an alternative embodiment, the acrylic acid derivative multipolymer includes at least one of LA132, LA133, LA136D, and LA136 DL; and/or

The water-resistant binder comprises modified polyacrylate; and/or

The modified polyacrylate comprises a styrene-acrylate copolymer; and/or

The heat-resistant binder includes at least one of a zwitterionic polyacrylamide and a sulfonate-type polyacrylamide.

As an alternative embodiment, the auxiliary agents include dispersants, wetting agents and flame retardants; and/or

The dispersing agent comprises at least one of sodium hexametaphosphate, sodium pyrophosphate and sodium polyacrylate; and/or

The wetting agent comprises at least one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether and polyvinyl alcohol; and/or

The flame retardant comprises at least one of tributyl phosphate, dimethyl methylphosphonate and bismaleimide.

As an alternative embodiment, the coating comprises the following components in parts by mass: 20-50 parts of functional material, 0.05-8 parts of binder, 0.05-5 parts of dispersing agent, 0.001-2 parts of wetting agent and 0.05-5 parts of flame retardant, wherein the functional material comprises MOF (metal oxide fiber) base material and/or oxide electrolyte material.

As an alternative embodiment, the coating comprises a first coating and a second coating, both of which are attached to the base film.

In a second aspect, the present application provides an electrode assembly comprising a negative electrode sheet, a positive electrode sheet, and the separator provided in the first aspect disposed between the negative electrode sheet and the positive electrode sheet.

In a third aspect, the present application provides a battery comprising the electrode assembly provided in the second aspect.

In a fourth aspect, the present application provides an electrical device comprising the battery provided in the third aspect.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

According to the diaphragm provided by the embodiment of the application, the cellulose diaphragm and the polymer diaphragm are compounded, and the high heat resistance stability of the cellulose diaphragm and the high tensile strength of the polymer diaphragm are utilized, so that the diaphragm has the characteristics of good heat stability and high tensile strength, and the problem of poor heat stability of the diaphragm is solved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.

FIG. 1 is a schematic diagram of a separator according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a separator according to an embodiment of the present application.

Reference numerals: 1-base film, 11-first base film, 12-tie layer, 13-second base film, 2-coating, 21-first coating, 22-second coating.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.

Aiming at the defects of the thermal stability difference modification technology existing in the current electrolyte membrane, such as larger density of ceramic coating materials and poor ion conductivity, the energy density of the battery is reduced; inorganic solid electrolytes include lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum titanium oxide, lithium lanthanum zirconium oxide, complex and expensive preparation methods limit their applicability; the self-supporting solid electrolyte membrane without the base membrane has the problems of low tensile strength, difficult control of thickness and the like.

The application aims to provide a high-strength and high-heat-resistance ultrathin composite electrolyte membrane, which is characterized in that through the design of a composite base membrane, the design of a water-resistant and heat-resistant binder and the adoption of an MOF base material with a highly ordered nano pore structure as a slurry coating, the design of a composite multi-coating is carried out on the surface of the base membrane, the room-temperature ionic conductivity of the developed electrolyte membrane can reach 1.0mS/cm, the thickness is controlled below 30 mu m, the thermal shrinkage is less than 5% at the temperature of 180 ℃, and the tensile strength can reach more than 100 MPa.

Fig. 1 and fig. 2 are schematic structural diagrams of a membrane provided by an embodiment of the present application, and as shown in fig. 1 and fig. 2, the embodiment of the present application provides a membrane, where the membrane includes a base membrane and a coating layer, the coating layer is attached to at least a partial area of the base membrane, the base membrane includes a first base membrane, a bonding layer, and a second base membrane, the bonding layer is disposed between the first base membrane and the second base membrane, the first base membrane is a cellulose membrane, and the second base membrane is a polymer membrane.

By at least a partial region of the base film to which the coating is attached is meant at least a partial region of one or both sides of the separator to which the coating may be attached. In some embodiments, the coating may include a first coating and a second coating, both of which are adhered to the base film. The attachment relationship of the first and second coatings and the base film may be direct attachment or indirect attachment. For example, it may be that the first coating layer and the second coating layer are directly attached to opposite sides of the base film, respectively, as shown in fig. 1; it is also possible that the first coating and the second coating are both provided on the same side of the base film, and that one of the coatings and the base film is directly attached and the other coating and the base film is indirectly attached, as shown in fig. 2.

According to the membrane, the cellulose membrane and the polymer membrane are compounded, and the high heat resistance stability of the cellulose membrane and the high tensile strength of the polymer membrane are utilized, so that the membrane has the characteristics of good thermal stability and high tensile strength, and the problem of poor thermal stability of the membrane is solved.

In some embodiments, the components of the cellulosic separator include at least one of cellulose fibers and heat resistant polyphenylene sulfide fibers; the composition of the polymeric separator comprises polyethylene.

In some embodiments, the composition of the tie layer comprises a (polyvinylidene fluoride-hexafluoropropylene) copolymer (VDF-HFP). PVDF-HFP has ion conductivity and uniform pore structure, and plays a role in bonding and widens the transmission channel of lithium ions.

In some embodiments, the composition of the coating includes a functional material, a binder, and an auxiliary agent, wherein the functional material includes a MOF-based material and/or an oxide electrolyte material. The MOF-based material has highly ordered nano pores, and the membrane modified by the MOF-based material can ensure uniform transmission of lithium ions in the nano channels, realize the effect of uniform lithium ion flow, realize stable and dendrite-free lithium negative electrode and ensure that the lithium metal battery has excellent cycle and rate performance.

In some embodiments, the MOF-based material comprises at least one of ZIF-8, ZIF-67, MOF-199, MOF-74, and UIO-66; the oxide electrolyte material includes at least one of lithium aluminum titanium phosphate and lithium lanthanum zirconium oxide. Further, the functional material has a particle diameter of 0.3 μm to 3 μm.

The conventional binder has poor conductivity, can reduce the air permeability and ion conductivity of the diaphragm in the diaphragm, is easy to shrink when heated at high temperature, and in addition, the conventional binder contains hydroxyl and is easy to absorb moisture, so that the moisture is higher; therefore, it is necessary to select a binder having high heat and water resistance, and to reduce the amount of the binder as much as possible. However, since it is generally difficult to combine the above properties with one binder, a plurality of binders can be used in combination to complement the advantages. In some embodiments, the binder comprises at least two binders. Further, the binder includes a first binder, a second binder and a third binder, the first binder is an acrylic acid derivative multipolymer, and the acrylic acid derivative multipolymer can be selected from at least one of LA132, LA133, LA136D and LA136DL, has higher relative acrylic acid molecular weight, low swelling degree and stronger binding force, can reduce the consumption of the binder, the second binder is a water-resistant binder, and the water-resistant binder can be selected from modified polyacrylate, and further, the modified polyacrylate can be selected from styrene-acrylate copolymer, which has excellent water resistance and weather resistance; the third binder is a heat-resistant binder, and the heat-resistant binder may be selected from at least one of zwitterionic polyacrylamides and sulfonate polyacrylamides, with a heat-resistant temperature of up to 200 ℃. By mixing a plurality of binders, the amount of the binders can be reduced on the premise of having better bonding effect, and meanwhile, the water resistance and the heat resistance are better.

In some embodiments, the auxiliary agents include dispersants, wetting agents, and flame retardants; the dispersing agent comprises at least one of sodium hexametaphosphate, sodium pyrophosphate and sodium polyacrylate; the wetting agent comprises at least one of polyoxyethylene alkylphenol ether, polyoxyethylene fatty alcohol ether and polyvinyl alcohol; the flame retardant comprises at least one of tributyl phosphate, dimethyl methylphosphonate and bismaleimide. Further, the coating comprises the following components in parts by mass: 20 to 50 parts of functional material, 0.05 to 8 parts of binder, 0.05 to 5 parts of dispersing agent, 0.001 to 2 parts of wetting agent and 0.05 to 5 parts of flame retardant.

According to the application, through the design of a composite base film, the design of a water-resistant and heat-resistant binder and the adoption of a MOF base material with a highly ordered nano pore structure as a slurry coating, the design of a composite multi-coating is carried out, and finally, the high-strength, high-heat-resistant and ultrathin composite electrolyte film is obtained. The composite electrolyte membrane mainly comprises MOF base materials, polymer electrolyte, dispersing agents, wetting agents and flame retardants. The MOF-based material has the advantages of good heat stability, low cost, low density, high specific surface area and the like, and is widely applied to the field of batteries. The MOF-based material has highly ordered nano pores, and the membrane modified by the MOF-based material can ensure uniform transmission of lithium ions in the nano channels, realize the effect of uniform lithium ion flow, realize stable and dendrite-free lithium negative electrode and ensure that the lithium metal battery has excellent cycle and rate performance. The composite electrolyte membrane has high ionic conductivity, low thickness, low interface resistance, excellent mechanical strength and thermal stability, and in addition, the electrolyte membrane has controllable thickness, can realize large-scale preparation, and has extremely high commercial value in high-energy-density all-solid-state batteries.

Based on one general inventive concept, an embodiment of the present application also provides an electrode assembly including a negative electrode sheet, a positive electrode sheet, and the separator provided as above disposed between the negative electrode sheet and the positive electrode sheet.

The electrode assembly is prepared based on the separator, and the specific content of the separator can refer to the embodiment, and because the electrode assembly adopts part or all of the technical solutions of the embodiment, the electrode assembly has at least all of the beneficial effects brought by the technical solutions of the embodiment, and the description is omitted herein.

The electrode assembly may be a wound structure or a lamination structure, and embodiments of the present application are not limited thereto. Meanwhile, the present application is not particularly limited to the positive electrode sheet and the negative electrode sheet.

In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer covering at least one surface of the positive electrode current collector in a thickness direction thereof; the positive electrode current collector without the positive electrode active material layer protrudes out of the positive electrode current collector with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer serves as a positive electrode tab. The material of the positive electrode current collector can comprise aluminum foil, foamed aluminum, an aluminum composite current collector (a high polymer supporting layer is arranged in the middle, and the current collectors of aluminum metal layers are arranged on two surfaces of the supporting layer), nickel foil, foamed nickel and the like; the positive electrode active material in the positive electrode active material layer includes one or a mixture of several of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-containing phosphate of olivine structure, for example, nickel cobalt lithium manganate, nickel cobalt lithium aluminate, lithium cobaltate, lithium iron phosphate, lithium manganate, and the like; the binder in the positive electrode active material layer is selected from at least one of vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylate, carboxymethyl cellulose sodium salt, styrene-butadiene rubber, polyurethane, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer; the dispersing agent in the positive electrode active material layer is selected from polyvinylpyrrolidone and the like; the conductive particles in the positive electrode active material layer are selected from at least one of conductive carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, graphene, activated carbon, graphite flakes, graphite particles, and mesophase carbon microspheres.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining the positive electrode plate after the procedures of drying, cold pressing and the like.

In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer covering at least one surface of the negative electrode current collector in a thickness direction; the negative electrode current collector without the negative electrode active material layer protrudes from the negative electrode current collector with the coated negative electrode active material layer, and the negative electrode current collector without the coated negative electrode active material layer serves as a negative electrode tab. The material of the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal, etc., wherein the conductive metal includes but is not limited to copper, nickel, or titanium, and the material of the polymer substrate includes but is not limited to at least one of polyethylene, polypropylene, ethylene propylene copolymer, polyethylene terephthalate, polyethylene naphthalate, and poly-p-phenylene terephthalamide; the anode active material in the anode active material layer includes carbon materials including, but not limited to, at least one of hard carbon, soft carbon, amorphous carbon, nanostructured carbon materials, etc., which are commercially available, lithium simple substances, alloys of lithium with other metallic elements or nonmetallic elements. The metal element includes tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), foil (Pt), etc., and the nonmetal element includes boron (B), carbon (C), silicon (Si), etc.

Based on one general inventive concept, embodiments of the present application also provide a battery including the electrode assembly provided above.

The battery is prepared based on the electrode assembly, the specific content of the electrode assembly can refer to the embodiment, and the battery adopts part or all of the technical schemes of the embodiment, so that the battery has at least all of the beneficial effects brought by the technical schemes of the embodiment, and the details are not repeated here.

In the present application, a battery may refer to a single battery cell, which may also refer to a single physical module including a plurality of battery cells to provide higher voltage and capacity, which may be in the form of a battery pack, a battery module, or the like. The battery may include a case for packaging a plurality of battery cells, and the case may prevent liquid or other foreign matter from affecting the charge or discharge of the battery cells.

The battery comprises a box body and a battery monomer, and the battery monomer is accommodated in the box body. The box is used for providing accommodation space for the battery monomer. In some embodiments, the case may include a first portion and a second portion that are overlapped with each other to define a receiving space for receiving the battery cell. Of course, the connection between the first portion and the second portion may be sealed by a sealing member, which may be a sealing ring, a sealant, or the like.

The first and second portions may be of various shapes, such as rectangular parallelepiped, cylindrical, etc. The first part may be a hollow structure having one side opened to form a receiving cavity for receiving the battery cell, and the second part may be a hollow structure having one side opened to form a receiving cavity for receiving the battery cell, and the opening side of the second part is closed to the opening side of the first part, thereby forming a case having a receiving space. Of course, the first portion may be a hollow structure with one side open, the second portion may be a plate-like structure, and the second portion may be covered on the open side of the first portion to form a case having an accommodating space.

In the battery, a plurality of battery monomers can be connected in series or in parallel or in series-parallel connection, and the series-parallel connection means that the plurality of battery monomers are connected in series or in parallel. The plurality of battery monomers can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the plurality of battery monomers is accommodated in the box body; of course, a plurality of battery cells may be connected in series or in parallel or in series-parallel to form a battery module, and then the plurality of battery modules are connected in series or in parallel or in series-parallel to form a whole and are accommodated in the box body. The battery cells may be cylindrical, flat, rectangular, or otherwise shaped.

In some embodiments, the battery may further include a bus member through which electrical connection between the plurality of battery cells may be achieved to achieve serial or parallel connection or series-parallel connection of the plurality of battery cells.

In some embodiments, a battery cell may include a housing, an end cap assembly, and an electrode assembly. The case has an opening, the electrode assembly is accommodated in the case, and the cap assembly is used for closing the opening.

The shape of the case may be determined according to the specific shape of the electrode assembly. For example, if the electrode assembly has a rectangular parallelepiped structure, the case may have a rectangular parallelepiped structure. The material of the housing may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., which is not particularly limited in the embodiment of the present application.

The end cap assembly includes an end cap and an electrode terminal. The end cap assembly is used for sealing the opening of the casing to form a closed installation space, and the installation space is used for accommodating the electrode assembly. The installation space is also used for accommodating an electrolyte, such as an electrolyte solution. The end cap assembly is used as a component for outputting electric energy of the electrode assembly, and the electrode terminal in the end cap assembly is used for being electrically connected with the electrode assembly, namely, the electrode terminal is electrically connected with the electrode lug of the electrode assembly, for example, the electrode terminal is connected with the electrode lug through the current collecting member, so that the electrode terminal is electrically connected with the electrode lug.

It should be noted that the openings of the housing may be one or two. If the opening of the shell is one, the end cover component can also be one, and two electrode terminals can be arranged in the end cover component and are respectively used for being electrically connected with the positive electrode lug and the negative electrode lug of the electrode component. If the number of the openings of the housing is two, for example, the two openings are disposed on two opposite sides of the housing, the number of the end cover assemblies may be two, and the two end cover assemblies are respectively covered at the two openings of the housing. In this case, it may be that the electrode terminal in one end cap assembly is a positive electrode terminal for electrical connection with the positive electrode tab of the electrode assembly; the electrode terminal in the other end cap assembly is a negative electrode terminal for electrical connection with a negative electrode tab of the electrode assembly.

In some embodiments, the battery cell may further include an insulation protection member fixed to an outer circumference of the electrode assembly, the insulation protection member for insulating the electrode assembly from the case. Illustratively, the insulating protector is an adhesive tape bonded to the outer circumference of the electrode assembly. In some embodiments, the number of the electrode assemblies is plural, the insulating protection member is disposed around the outer circumferences of the electrode assemblies, and the electrode assemblies are formed into a unitary structure to keep the electrode assembly structure stable.

In some embodiments, the battery further includes an electrolyte that serves to conduct ions between the positive and negative electrode sheets. The application is not particularly limited in the kind of electrolyte, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may 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 difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.

In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

The battery may be used, but is not limited to, in electrical devices such as vehicles, boats or aircraft. A power supply system having the battery or the like disclosed in the present application constituting the power consumption device may be used.

The embodiment of the application also provides an electric device using the battery as a power supply, wherein the electric device can be, but is not limited to, a mobile phone, a flat plate, a notebook computer, an electric toy, an electric tool, a battery car, an electric automobile, a ship, a spacecraft and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

For convenience of description, the following embodiments will take an electric device according to an embodiment of the present application as an example of a vehicle.

The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like. The interior of the vehicle is provided with a battery, which may be provided at the bottom or at the head or at the tail of the vehicle. The battery may be used for power supply of the vehicle, for example, the battery may be used as an operating power source of the vehicle. The vehicle may also include a controller and a motor, the controller being configured to control the battery to power the motor, for example, for operating power requirements during start-up, navigation, and travel of the vehicle.

In some embodiments of the application, the battery may be used not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, instead of or in part instead of fuel oil or natural gas, to provide driving power for the vehicle.

The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.

Example 1

The present embodiment provides a separator, the preparation steps of which include:

1) Preparing a first coating slurry: sequentially weighing 28% of an inorganic material MOF-based UIO-66 material according to the following weight percentage, wherein the proportion of the first binder is 0.2% of LA136D, the proportion of the second binder is 4.0% of a styrene-acrylate copolymer, the proportion of the third binder is 1.0% of a sulfonate type polyacrylamide, the proportion of a dispersing agent is 0.5% of a sodium polyacrylate salt, the proportion of a wetting agent is 0.1% of polyvinyl alcohol, the proportion of a flame retardant is 0.5% of bismaleimide and 65.7% of water, mixing, stirring, fully dispersing, and stirring for 24 hours to obtain first coating slurry;

2) Preparing a second coating slurry: weighing 28% of LATP oxide electrolyte material according to the following weight percentage, wherein the proportion of the first binder is 0.2% of LA136D, the proportion of the second binder is 4.0% of styrene-acrylic ester copolymer, the proportion of the third binder is 1.0% of sulfonate type polyacrylamide, the proportion of the dispersing agent is 0.5% of sodium polyacrylate, the proportion of the wetting agent is 0.1% of polyvinyl alcohol, the proportion of the flame retardant is 0.5% of bismaleimide and 65.7% of water, mixing and stirring, fully dispersing, and stirring for 24 hours to obtain second coating slurry;

3) Preparing a composite base film: uniformly spreading PVDF-HFP solution (dissolved in N-methylpyrrolidone) with the concentration of 2% on the surface of a PE base film, spreading a cellulose diaphragm on one surface with the PVDF-HFP solution, and carrying out vacuum for 12h at 80 ℃ to obtain the PE/PVDF-HFP/cellulose composite base film;

4) And (3) respectively coating the slurries of the step (1) and the step (2) on two sides of the step (3), controlling the thickness of a single layer to be about 3 mu m, and vacuum-coating for 12 hours at 80 ℃ to obtain the double-coating diaphragm.

Example 2

1) Preparing coating slurry: the inorganic material MOF-based UIO-66 material is weighed according to the following weight percentage, wherein the proportion of the first binder is 0.2 percent, the proportion of the second binder is 4.0 percent, the proportion of the third binder is 1.0 percent, the proportion of the third binder is 0.5 percent, the proportion of the dispersing agent is 0.1 percent, the proportion of the wetting agent is 0.5 percent, the proportion of the flame retardant is 0.5 percent, the proportion of the bismaleimide is 65.7 percent, the mixture is mixed and stirred, fully dispersed and stirred for 24 hours to obtain coating slurry;

2) Preparing a composite base film: uniformly spreading PVDF-HFP solution (dissolved in N-methylpyrrolidone) with the concentration of 2% on the surface of a PE base film, spreading a cellulose diaphragm on one surface with the PVDF-HFP solution, and carrying out vacuum for 12h at 80 ℃ to obtain the PE/PVDF-HFP/cellulose composite base film;

3) And (3) respectively coating the slurry in the step (1) on the two sides of the step (2), controlling the thickness of a single layer to be about 3 mu m, and vacuum-coating for 12 hours at 80 ℃ to obtain the double-coating diaphragm.

Example 3

1) Preparing coating slurry: weighing 28% of LATP oxide electrolyte material according to the following weight percentage, wherein the proportion of the first binder is 0.2% of LA136D, the proportion of the second binder is 4.0% of styrene-acrylic ester copolymer, the proportion of the third binder is 1.0% of sulfonate type polyacrylamide, the proportion of the dispersing agent is 0.5% of sodium polyacrylate, the proportion of the wetting agent is 0.1% of polyvinyl alcohol, the proportion of the flame retardant is 0.5% of bismaleimide and 65.7% of water, mixing and stirring, fully dispersing, and stirring for 24 hours to obtain coating slurry;

3) Coating the slurry in the step 1) on the two sides of the step 2) respectively, controlling the thickness of a single layer to be about 3 mu m, vacuum-coating for 12 hours at 80 ℃ to obtain a double-coating diaphragm,

Example 4

4) And (3) sequentially coating the slurries of the step (1) and the step (2) on the cellulose surface of the step (3), controlling the single-layer thickness to be about 3 mu m, and vacuum-coating at 80 ℃ for 12 hours to obtain the double-coating diaphragm.

Example 5

4) And (3) sequentially coating the slurries of the step (1) and the step (2) on the PE surface of the step (3), controlling the single-layer thickness to be about 3 mu m, and vacuum-coating at 80 ℃ for 12 hours to obtain the double-coating diaphragm.

Comparative example 1

This comparative example provides a separator, the preparation steps of which include:

1) Preparing a first coating slurry: sequentially weighing 28% of an inorganic material MOF-based UIO-66 material, wherein the proportion of the binder is LA136D and is 5.2%, the dispersing agent is sodium polyacrylate salt 0.5%, the wetting agent is polyvinyl alcohol 0.1%, the flame retardant is bismaleimide 0.5% and water 65.7%, mixing and stirring, fully dispersing, and stirring for 24 hours to obtain first coating slurry;

2) Preparing a second coating slurry: weighing 28% of LATP oxide electrolyte material, 5.2% of binding agent LA136D, 0.5% of sodium polyacrylate as dispersing agent, 0.1% of polyvinyl alcohol as wetting agent, 0.5% of bismaleimide as flame retardant and 65.7% of water in sequence according to the following weight percentage, mixing and stirring, fully dispersing, and stirring for 24 hours to obtain second coating slurry;

Comparative example 2

3) The base film is a PE single-layer base film;

Comparative example 3

2) The base film is a PE single-layer base film;

The separators provided in each of the examples and comparative examples were subjected to performance tests, and the results are shown in the following table:

As can be seen from the above table, by comparing example 1 and comparative example 2, the separator using the composite base film has higher thermal stability and higher ionic conductivity at the same coating and thickness, and the applicant has suggested that the reason is due to the high heat resistance of cellulose and the high conductivity of PVDF-HFP; as can be seen from the comparison of example 1 and comparative example 1, the heat resistance was higher when a plurality of binders were used in combination under the same base film, and the separator moisture was significantly reduced. And when the base film is the same, the double-sided MOF material has higher thermal stability.

Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1,2,3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.

In the present application, unless otherwise specified, terms such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present specification, the terms "include", "comprising" and the like mean "including but not limited to". Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c" may each denote: a. b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.

The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A separator, wherein the separator comprises a base film and a coating, the coating is attached to at least a partial area of the base film, the base film comprises a first base film, a bonding layer and a second base film, the bonding layer is arranged between the first base film and the second base film, the first base film is a cellulose separator, and the second base film is a polymer separator.

2. The separator of claim 1, wherein the components of the cellulosic separator include at least one of cellulose fibers and heat resistant polyphenylene sulfide fibers; and/or

The composition of the polymeric separator comprises polyethylene.

3. A separator according to claim 1 or 2, wherein the composition of the tie layer comprises a (polyvinylidene fluoride-hexafluoropropylene) copolymer.

4. The separator of claim 1, wherein the composition of the coating comprises a functional material, a binder, and an auxiliary agent, wherein the functional material comprises a MOF-based material and/or an oxide electrolyte material.

5. The diaphragm of claim 4 wherein the MOF-based material comprises at least one of ZIF-8, ZIF-67, MOF-199, MOF-74, and UIO-66; and/or

6. The separator according to claim 4 or 5, wherein the functional material has a particle size of 0.3 μm to 3 μm.

7. The separator of claim 4, wherein the binder comprises at least two binders.

8. The separator of claim 7, wherein the binder comprises a first binder, a second binder and a third binder, the first binder being an acrylic derivative multipolymer, the second binder being a water resistant binder, the third binder being a heat resistant binder.

9. The separator of claim 8, wherein the acrylic acid derivative multipolymer comprises at least one of LA132, LA133, LA136D, and LA136 DL; and/or

The water-resistant binder comprises modified polyacrylate; and/or

The modified polyacrylate comprises a styrene-acrylate copolymer; and/or

10. The separator of claim 4, wherein the auxiliary agent comprises a dispersant, a wetting agent, and a flame retardant; and/or

11. The membrane of claim 1, wherein the coating comprises the following components in parts by mass: 20-50 parts of functional material, 0.05-8 parts of binder, 0.05-5 parts of dispersing agent, 0.001-2 parts of wetting agent and 0.05-5 parts of flame retardant, wherein the functional material comprises MOF (metal oxide fiber) base material and/or oxide electrolyte material.

12. The separator of claim 1, wherein the coating comprises a first coating and a second coating, each of the first and second coatings being adhered to the base film.

13. An electrode assembly comprising a negative electrode sheet, a positive electrode sheet, and the separator of any one of claims 1 to 12 disposed between the negative electrode sheet and the positive electrode sheet.

14. A battery, characterized in that, the battery comprising the electrode assembly of claim 13.

15. An electric device is characterized in that, the power utilization device comprises the battery of claim 14.