WO2025234775A1 - All-solid-state battery - Google Patents

Abstract

The present disclosure provides an all-solid-state battery comprising: electrode assemblies each comprising an electrode stack which comprises a positive electrode, an electrolyte membrane, and a negative electrode, and a pair of protective layers which are positioned on the positive electrode side and the negative electrode side, respectively, of the electrode composite; and a separator zigzaggedly surrounding the electrode assemblies so that the electrode assemblies are positioned in the folded portions thereof.

Description

All-solid-state battery

This application claims the benefit of priority to Korean Patent Application No. 10-2024-0061280, filed May 9, 2024, and Korean Patent Application No. 10-2025-0057473, filed April 30, 2025, the entire contents of which are incorporated herein by reference.

The present disclosure relates to an all-solid-state battery. More specifically, the present disclosure relates to an all-solid-state battery having a structure in which an electrode laminate included in the all-solid-state battery is surrounded by a composite separator, wherein the composite separator is manufactured as a separator layer and a buffer layer, so that the electrode laminate can be well fixed by the buffer layer.

With the explosive growth in technological development and demand for mobile devices and automobiles, more research is being conducted on secondary batteries with high energy density, discharge voltage, and excellent output stability. Examples of these secondary batteries include lithium-sulfur batteries, lithium-ion batteries, and all-solid-state batteries.

Among these, all-solid-state batteries are superior to other types of secondary batteries in terms of safety, and are particularly in the spotlight in fields such as electric vehicles and mobile devices. In other words, all-solid-state batteries are batteries that replace the liquid electrolyte used in conventional lithium secondary batteries with a solid one. Consequently, they eliminate the use of flammable solvents, eliminating the risk of fire or explosion caused by decomposition reactions of conventional electrolytes, significantly improving safety. Furthermore, all-solid-state batteries can use lithium metal or lithium alloys as anode materials, offering the advantage of dramatically improving the energy density relative to the mass and volume of the battery.

Among these all-solid-state batteries, the most commonly used is the sulfide-based all-solid-state battery. During the manufacturing process, these sulfide-based all-solid-state batteries typically employ a warm isostatic pressing (WIP) process to ensure interfacial bonding between the electrodes and the solid electrolyte (i.e., wrapping the electrodes in a pouch, sealing them, and applying pressure). If the electrode-solid-electrolyte interface is not properly bonded, lithium ion movement is difficult, making battery operation impossible.

For these sulfide-based all-solid-state batteries, the Warm Isostatic Press (WIP) process must be applied for cell fabrication. This WIP process applies isotropic pressure using a solvent within a vessel. Therefore, when multiple electrodes and electrolyte layers are stacked and the WIP process is performed, the outermost electrode can become deformed by the WIP pressure, resulting in short circuits or deteriorated cycle life.

To solve this problem, a method has been attempted in which each unit cell undergoes a WIP process before stacking, and then the unit cells that have completed the WIP process are stacked. However, when applying driving pressure to drive the cells after stacking the unit cells, there is a problem in that the electrodes break or a short circuit occurs due to misalignment between the electrodes.

(Patent Document 1) Korean Patent Publication No. 10-2023-0059000

The present inventors have proposed to solve the above-mentioned problem, and the purpose of the present disclosure is to provide an all-solid-state battery having a structure that can minimize the occurrence of electrode breakage and short-circuiting of electrodes of an electrode assembly by fixing unit cells manufactured by a WIP process used when manufacturing a sulfide-based all-solid-state battery using a double-layer composite separator when stacking.

In order to achieve the above object, in one embodiment according to the present disclosure, an all-solid-state battery is provided, comprising: an electrode laminate including a positive electrode, an electrolyte membrane, and a negative electrode; and a composite separator that wraps the electrode laminate in a zigzag manner so that the electrode laminate is positioned at a folded portion, wherein the composite separator includes a separator layer and a buffer layer positioned on at least one surface of the separator layer.

Additionally, the separator layer may include any one material selected from the group consisting of polyethylene (PE), polypropylene (PP), and a resin blended with PE and PP.

Additionally, the buffer layer may include any one material selected from the group consisting of silicone, PTFE, polyurethane resin (PUR), polyolefin (PO), and polyamide (PA).

Additionally, the separation membrane layer may have a thickness of 4 to 10 μm.

Additionally, the buffer layer may have a thickness of 10 to 50 μm.

Additionally, the buffer layer can be in contact with the electrode laminate to fix the electrode assembly.

The above electrode stack may be in the form of a monocell or a bicell.

The above electrode stack may be in the form of an anodeless electrode.

An all-solid-state battery according to one embodiment of the present disclosure has the effect of minimizing the occurrence of electrode breakage and short circuit of an electrode assembly by fixing the unit cells using a composite separator having a double-layer structure when stacking the unit cells.

FIG. 1 is a drawing showing a laminated structure of an all-solid-state battery according to one embodiment of the present disclosure.

FIG. 2 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

FIG. 3 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

FIG. 4 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

FIG. 5 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

Hereinafter, the present disclosure will be described in more detail to help understand the present disclosure.

The terms and words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, but should be construed as meanings and concepts that conform to the technical spirit of the present disclosure, based on the principle that the inventor can appropriately define the concept of the term to best explain his or her own invention.

The term "electrode stack" used in this specification refers to the structure of an all-solid-state battery in which the positive electrode, electrolyte membrane, and negative electrode are simply stacked.

The term "electrode assembly" as used herein refers to a structure of an all-solid-state battery that includes additional components other than the electrode laminate. For example, in this specification, it refers to a structure of an all-solid-state battery that additionally includes a protective layer in addition to the electrode laminate.

is a drawing showing a unit cell of an all-solid-state battery according to one embodiment of the present disclosure.

Referring to FIG. 1, an all-solid-state battery according to one embodiment of the present disclosure includes an electrode laminate including a positive electrode (2), an electrolyte membrane (3), and a negative electrode (4); and a composite separator (6, 7) that wraps the electrode laminate in a zigzag manner so that the electrode laminate is positioned at a folded portion, wherein the composite separator (6, 7) includes a separator layer (7) and a buffer layer (6) positioned on at least one surface of the separator layer.

An electrode stack of an all-solid-state battery according to one embodiment of the present disclosure includes an electrode stack including a positive electrode (2), an electrolyte membrane (3), and a negative electrode (4).

An electrode laminate according to one embodiment of the present disclosure may include an anode (2).

According to one embodiment of the present disclosure, a positive electrode can be used without any particular limitation as long as it is used in an all-solid-state battery, and may include, for example, a positive electrode active material, a solid electrolyte, a conductive material, and a binder. Among these, the positive electrode active material can be used without limitation as long as it can be used as a positive electrode active material for an all-solid-state battery. The positive electrode active material may be a lithium transition metal oxide containing one or more transition metals. For example, the positive electrode active material is selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , Li ₂ MnO ₃ , LiMn ₂ O ₄ , Li(Ni _a Co _b Mn _c )O ₂ (0<a<1, 0<b<1, 0<c<1, a+b+c=1), LiNi _1-y Co _y O ₂ (O<y<1), LiCo _1-y Mn _y O ₂ , LiNi _1- y Mn _y O ₂ (O<y<1), Li(Ni _a Co _b Mn _c )O ₄ (0<a<2, 0<b<2, 0<c<2, a+b+c=2), LiMn _2-z Ni _z O ₄ (0<z<2), LiMn _2-z Co _z O ₄ (0<z<2) and combinations thereof. It could be.

In addition, the binder is mixed with the positive electrode active material and conductive material, which are fine particles in a powder state, to bind each component and help the growth of the particles. For example, since a sulfide-based solid electrolyte has a moisture-sensitive characteristic such as generating _H2S gas when in contact with moisture, it is desirable to exclude moisture as much as possible from the time of forming the granules. The binder may be an organic binder, and the organic binder means a binder that is dissolved or dispersed in an organic solvent, particularly N-methylpyrrolidone (NMP), and is distinguished from an aqueous binder that uses water as a solvent or dispersion medium. For example, the binder may be selected from the group consisting of, but is not limited to, polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polyimide, polyamideimide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butylene rubber, and fluoroelastomer.

An electrode laminate according to one embodiment of the present disclosure may include an electrolyte membrane (3). The electrolyte membrane may include a solid electrolyte, and the solid electrolyte may include at least one selected from a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte, and it may be preferable to include only a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may include a lithium salt, and the lithium salt may be an ionizable lithium salt and may be expressed as Li ⁺ X ^- . The anions of these lithium salts are not particularly limited, but include F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , CF ₃ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- _, CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , (CF ₃ SO ₂ ) ₃ C ^- , CF ₃ (CF ₂ ) ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- can be exemplified.

In addition, the sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic. Non-limiting examples of such sulfide-based solid electrolytes include Li ₂ SP ₂ S ₅ , Li ₂ S-LiI-P ₂ S ₅ , Li ₂ S-LiI-Li ₂ OP ₂ S ₅ , Li ₂ S-LiBr-P ₂ S ₅ , Li ₂ S-LiCl-P ₂ S ₅ , Li ₂ S-Li ₂ OP ₂ S ₅ , Li ₂ S-Li ₃ PO ₄ -P ₂ S ₅ , Li ₂ SP ₂ S ₅ -P ₂ O ₅ , Li ₂ SP ₂ S ₅ -SiS ₂ , Li ₂ SP ₂ S ₅ -SnS, Li ₂ SP ₂ S ₅ -Al ₂ S ₃ , Li ₂ S-GeS ₂ , and Li ₂ S-GeS ₂ -ZnS, and the sulfide-based solid electrolyte may include any one or more thereof.

These solid electrolytes can perform the same role as separators in conventional lithium secondary batteries (i.e., electrically insulating the anode and cathode while simultaneously allowing lithium ions to pass through). Meanwhile, the all-solid-state battery can be utilized as a semi-solid battery by including a liquid electrolyte, if necessary. In this case, a separate polymer separator may be required.

An electrode laminate according to one embodiment of the present disclosure may include a negative electrode (4). The negative electrode may include a negative electrode active material usable in a typical all-solid-state battery. For example, the negative electrode active material may include carbon such as non-graphitizable carbon, graphitic carbon, etc.; metal composite oxides such as Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _1-x Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Group 1, Group 2, and Group 3 of the Periodic Table, halogen; 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; It may include _{at least one selected from metal oxides such as SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO ,} GeO 2 , Bi ₂ O ₃ , Bi 2 O 4 and Bi ₂ O ₅ ; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxide; lithium titanium oxide; etc.

An electrode laminate according to one embodiment of the present disclosure may be in the form of an anodeless battery (anodeless battery).

When the electrode laminate according to one embodiment of the present disclosure is an anodeless battery, it refers to a battery that is driven by a mechanism in which no lithium metal exists on the negative electrode current collector or exists only in a small amount when the battery is first manufactured, but metallic lithium is precipitated between the negative electrode active material layer and the current collector by charging the battery to form a lithium metal layer, and when discharging, the metallic lithium is ionized and moves toward the positive electrode.

The above anode-less battery may not have a negative electrode active material layer when the battery is first manufactured. When explaining based on the electrode laminate of Fig. 1, when the battery is first manufactured, no negative electrode active material exists on the negative electrode current collector as shown in Fig. 5. However, a lithium metal layer formed by charging and deposited on the negative electrode current collector may function as a negative electrode.

The negative electrode of the above anodeless battery may have a negative electrode structure including, for example, a negative electrode active material layer including a metal that forms an alloy with lithium and a carbon material.

The thickness of the above negative electrode active material layer can typically be formed in a range of 1 ㎛ to 100 ㎛, or 10 ㎛ to 60 ㎛, and specifically, can be formed in a thickness of 10 ㎛, 20 ㎛, 30 ㎛, 40 ㎛, 50 ㎛, etc., but is not necessarily limited thereto.

An all-solid-state battery according to one embodiment of the present disclosure includes a composite separator (6, 7).

The above composite separation membrane (6, 7) includes a separation membrane layer (7) and a buffer layer (6) positioned on at least one side of the separation membrane layer, and preferably, the buffer layer (6) can be formed on both sides of the separation membrane layer (7).

In an all-solid-state battery according to one embodiment of the present disclosure, the composite separator (6, 7) can fix the electrode stack.

There is no particular limitation on the separator layer as long as it is a general separator used in a secondary battery, but preferably, a separator using at least one material selected from the group consisting of polyethylene (PE), polypropylene (PP), and a resin mixed with PE and PP can be used.

In an all-solid-state battery according to one embodiment of the present disclosure, a positive electrode current collector (1) may be positioned on the positive electrode and composite separator (6, 7) of the electrode laminate, and a negative electrode current collector (5) may be positioned on the negative electrode and composite separator (6, 7) of the electrode assembly.

In an all-solid-state battery according to one embodiment of the present disclosure, the buffer layer (6) may include any one material selected from the group consisting of silicon, PTFE, polyurethane resin (PUR), polyolefin (PO), and polyamide (PA).

In an all-solid-state battery according to one embodiment of the present disclosure, the separator layer may have a thickness of 4 to 10 μm, preferably 5 μm or more, 6 μm or more, or 7 μm or more, and may have a thickness of 9 μm or less, 8 μm or less, or 7 μm or less.

In an all-solid-state battery according to one embodiment of the present disclosure, the buffer layer (6) may have a thickness of 10 to 50 μm, preferably 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more, and may have a thickness of 45 μm or less, 40 μm or less, 35 μm or less, or 30 μm or less.

In an all-solid-state battery according to one embodiment of the present disclosure, the buffer layer (6) can be in contact with the electrode laminate to fix the electrode assembly.

In an all-solid-state battery according to one embodiment of the present disclosure, an electrode laminate including a positive electrode (2), an electrolyte membrane (3), and a negative electrode (4) can have various structures.

Specifically, the electrode stack may be in the form of a monocell or a bicell.

Specifically, in the all-solid-state battery according to one embodiment of the present disclosure, the electrode stack may have a structure of a single-sided electrode as shown in Fig. 1. In the all-solid-state battery according to one embodiment of the present disclosure, the single-sided electrode may mean an electrode in which an electrode layer is formed on only one side of a current collector (foil).

In the all-solid-state battery according to one embodiment of the present disclosure, the electrode stack may have a C-type structure as shown in FIG. 2. In the all-solid-state battery according to one embodiment of the present disclosure, the C-type structure may mean a structure in which an electrode having a positive electrode layer formed on both sides of a current collector (foil) is positioned at the center, and an electrode having an electrolyte layer formed on both sides and a negative electrode layer formed on one side of the current collector (foil) is positioned.

In the all-solid-state battery according to one embodiment of the present disclosure, the electrode stack may have an A-type structure as shown in FIG. 3. In the all-solid-state battery according to one embodiment of the present disclosure, the A-type structure may mean a structure in which an electrode having a negative electrode layer formed on both sides of a current collector (foil) is positioned at the center, and an electrode having an electrolyte layer formed on both sides and a positive electrode layer formed on one side of the current collector (foil) is positioned.

In the all-solid-state battery according to one embodiment of the present disclosure, the electrode stack may have a multi-unit cell structure as shown in FIG. 4. In the all-solid-state battery according to one embodiment of the present disclosure, the multi-unit cell means that, in order to improve energy density, more double-sided electrodes are used than in a general unit cell. For example, as shown in FIG. 4, it may mean a structure in which an electrode having a negative electrode layer formed on both sides of a current collector (foil) is positioned at the center, an electrode having an electrolyte layer and a positive electrode layer formed on both sides of the current collector (foil) is positioned on both sides of the electrode, and then an electrode having a negative electrode layer formed on one side of the current collector (foil) is positioned at the outermost end.

In addition, the present disclosure provides a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

Although the present disclosure has been described above with reference to limited embodiments and drawings, the present disclosure is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of the present disclosure and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present disclosure pertains.

[Explanation of symbols]

1: Positive current collector

2: Bipolar

3: Electrolyte membrane

4: Cathode

5: Negative current collector

6: Buffer layer

7: Membrane layer

Claims (8)

An electrode laminate comprising an anode, an electrolyte membrane, and a cathode; and A composite separator is included that wraps the electrode laminate in a zigzag pattern so that the electrode laminate is positioned at the folded portion, The above composite membrane comprises a membrane layer and a buffer layer positioned on at least one side of the membrane layer. All-solid-state battery. In the first paragraph, The above separation membrane layer is characterized in that it comprises any one material selected from the group consisting of polyethylene (PE), polypropylene (PP), and a resin mixed with PE and PP. All-solid-state battery. In the first paragraph, The buffer layer is characterized in that it comprises any one material selected from the group consisting of silicone, PTFE, polyurethane resin (PUR), polyolefin (PO), and polyamide (PA). All-solid-state battery. In the first paragraph, The above separation membrane layer is characterized in that it has a thickness of 4 to 10 ㎛. All-solid-state battery. In the first paragraph, The buffer layer is characterized in that it has a thickness of 10 to 50 ㎛. All-solid-state battery. In the first paragraph, The buffer layer is characterized in that it contacts the electrode laminate and fixes the electrode assembly. All-solid-state battery. In the first paragraph, The electrode stack is characterized in that it is in the form of a monocell or bicell. All-solid-state battery. In the first paragraph, The above electrode stack is characterized in that it is in the form of an anodeless battery. All-solid-state battery.