All-solid-state battery

Abstract

The present invention provides an all-solid-state battery including electrode assemblies each including an electrode laminate including a positive electrode, an electrolyte film, and a negative electrode; and a pair of protective layers located on the positive electrode side and the negative electrode side of the electrode composite, respectively; and a separator wrapped around the electrode assemblies in a zigzag manner such that the electrode assemblies are positioned in the folded portions thereof.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2024-0061280, filed on May 9, 2024, and Korean Patent Application No. 10-2025-0057473, filed on April 30, 2025, the disclosures of which are incorporated herein by reference in their entirety.

[0002] This invention relates to all-solid-state batteries. More specifically, this invention relates to an all-solid-state battery in which an electrode stack inside the battery is surrounded by a composite separator, wherein the composite separator is composed of a separator layer and a buffer layer. This structure ensures that the electrode stack is firmly fixed by the buffer layer. Background Technology

[0003] With the technological advancements and explosive growth in demand for mobile devices and automobiles, more research is focusing on secondary batteries with high energy density, high discharge voltage, and good output stability. Examples of such secondary batteries include lithium-sulfur batteries, lithium-ion batteries, and all-solid-state batteries.

[0004] Solid-state batteries are gaining attention due to their superior safety compared to other types of rechargeable batteries, particularly in electric vehicles and mobile devices. In other words, solid-state batteries replace the liquid electrolyte used in conventional lithium-ion batteries with a solid one. Therefore, since flammable solvents are not used, there is no possibility of fire or explosion due to the decomposition reaction of conventional electrolytes, significantly improving safety. Solid-state batteries also have the advantage of using lithium metal or lithium alloys as the negative electrode material, which can significantly improve the energy density relative to the battery's mass and volume.

[0005] The most commonly used all-solid-state batteries are sulfide-based all-solid-state batteries. During manufacturing, these sulfide-based all-solid-state batteries typically employ a warm isostatic pressing (WIP) process (i.e., wrapping the electrodes in a bag, sealing it, and pressurizing it) to achieve electrode-solid electrolyte interface bonding. If the electrode-solid electrolyte interface cannot be properly formed due to inadequate bonding, lithium (Li) ions will have difficulty migrating and the battery will not function.

[0006] In the case of sulfide-based all-solid-state batteries, a work-in-process (WIP) process must be applied during battery manufacturing. This WIP process involves applying isotropic pressure using a solvent within a container. However, when the WIP process is performed after stacking multiple electrode and electrolyte layers, the outermost electrode deforms under the WIP pressure, leading to problems such as short circuits or degraded lifetime characteristics.

[0007] To address this issue, a method has been proposed in which individual cell modules undergo a WIP (Work-In-Pack) process before being stacked. After the WIP process is complete, these cells are stacked. However, when driving pressure is applied to the stacked cell modules to make the battery work, misalignment between the electrodes can lead to electrode breakage or short circuits.

[0008] (Patent Document 1) Korean Patent Publication No. 10-2023-0059000 Summary of the Invention

[0009] [Technical Issues]

[0010] The inventors have proposed a solution to the aforementioned problems. The object of this invention is to provide an all-solid-state battery whose structure minimizes electrode breakage and short circuits during the stacking of cell units manufactured via a WIP process for sulfide-based all-solid-state batteries. This is achieved by using a composite separator with a double-layer structure to fix the electrode assembly.

[0011] [Technical Solution]

[0012] To achieve the above objectives, embodiments of the present invention provide an all-solid-state battery comprising an electrode stack and a composite separator. The electrode stack includes a positive electrode, an electrolyte membrane, and a negative electrode. The composite separator wraps around the electrode stack in a zigzag pattern and positions the electrode stack at a fold. The composite separator includes a separator layer and a buffer layer disposed on at least one surface of the separator layer.

[0013] In addition, the membrane layer may include at least one material selected from the group consisting of polyethylene (PE), polypropylene (PP), and resins made from blends of PE and PP.

[0014] In addition, the buffer layer may include at least one material selected from the group consisting of silicone, PTFE, polyurethane resin (PUR), polyolefin (PO) and polyamide (PA).

[0015] In addition, the thickness of the membrane layer can be from 4 μm to 10 μm.

[0016] In addition, the thickness of the buffer layer can be from 10 μm to 50 μm.

[0017] In addition, the buffer layer can contact the electrode stack to fix the electrode assembly.

[0018] The electrode stack can be a single cell or a dual cell.

[0019] The electrode stack can be in the form of an anode-free structure.

[0020] [Beneficial Effects]

[0021] One embodiment of the present invention provides an all-solid-state battery that minimizes electrode breakage and short circuits in the electrode assembly during the stacking of cell units by fixing the cell unit with a composite separator of a double-layer structure. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating the stacked structure of an all-solid-state battery according to one embodiment of the present invention.

[0023] Figure 2 This is a diagram illustrating the stacked structure of an all-solid-state battery according to another embodiment of the present invention.

[0024] Figure 3 This is a diagram illustrating the stacked structure of an all-solid-state battery according to another embodiment of the present invention.

[0025] Figure 4 This is a diagram illustrating the stacked structure of an all-solid-state battery according to another embodiment of the present invention.

[0026] Figure 5 This is a diagram illustrating the stacked structure of an all-solid-state battery according to another embodiment of the present invention. Detailed Implementation

[0027] The invention is described in more detail below to facilitate understanding of the invention.

[0028] The terms and words used in this specification and claims should not be interpreted in their ordinary or dictionary sense, but rather should be interpreted in a sense and in a sense consistent with the technical concept of the invention, based on the principle that the inventors may define the terms in a way that they deem most appropriate to describe their invention.

[0029] As used in this article, the term "electrode stack" refers to an all-solid-state battery structure consisting of a positive electrode, an electrolyte membrane, and a negative electrode stacked together.

[0030] As used herein, the term "electrode assembly" refers to an all-solid-state battery structure that includes additional components in addition to the electrode stack. For example, as used herein, it refers to an all-solid-state battery structure that includes a protective layer in addition to the electrode stack.

[0031] Figure 1 This is a diagram illustrating the stacked structure of an all-solid-state battery according to one embodiment of the present invention.

[0032] Reference Figure 1, an all-solid-state battery according to an embodiment of the present invention comprises an electrode laminate and composite separators (6,7), wherein the electrode laminate comprises a positive electrode (2), an electrolyte membrane (3) and a negative electrode (4), the composite separators (6, 7) wrap the electrode laminate in a zigzag pattern, and position the electrode laminate at a folded portion. The composite separators (6, 7) comprise a separator layer (7) and a buffer layer (6) disposed on at least one surface of the separator layer.

[0033] Best Mode

[0034] An electrode laminate for an all-solid-state battery according to an embodiment of the present invention comprises an electrode laminate including a positive electrode (2), an electrolyte membrane (3) and a negative electrode (4).

[0035] An electrode laminate according to an embodiment of the present invention may comprise a positive electrode (2).

[0036] The positive electrode according to an embodiment of the present invention may be any positive electrode without limitation as long as it is used for an all-solid-state battery, and may comprise, for example, a positive electrode active material, a solid electrolyte, a conductive material and a binder. Any positive electrode active material that can be used as a positive electrode active material in an all-solid-state battery can be used without limitation. The positive electrode active material may be a lithium transition metal oxide comprising one or more transition metals. For example, the positive electrode active material may be selected from LiCoO2, LiNiO2, LiMnO2, Li2MnO3, LiMn2O4, Li(Ni a Co b Mn c )O2 (wherein 0<a<1, 0<b<1, 0<c<1 and a+b+c=1), LiNi 1-y Co y O2 (wherein 0<y<1), LiCo 1-y Mn y O2, LiNi 1-y Mn y O2 (wherein 0<y<1), Li(Ni a Co b Mn c )O4 (0<a<2, 0<b<2, 0<c<2 and a+b+c=2), LiMn 2-z Ni z O4 (wherein 0<z<2), LiMn 2-z Co z O4 (wherein 0<z<2) and combinations thereof.

[0037] Additionally, the binder is mixed with the positive electrode active material and conductive material, which are powdered particles, to bind the components together and facilitate particle growth. For example, sulfide-based solid electrolytes are moisture-sensitive, producing H2S gas upon contact with water, thus it is desirable to remove as much moisture as possible from the particle formation process. The binder can be an organic binder, meaning a binder that is soluble or dispersible in an organic solvent (especially N-methylpyrrolidone (NMP)), as opposed to aqueous binders where water is used as a solvent or dispersion medium. For example, the binder can be selected from, but is not limited to, polyvinylidene fluoride (PVDF), ethylene-propylene-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polyimide, polyamide-imide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber.

[0038] An electrode stack according to one embodiment of the present invention may include an electrolyte membrane (3). The electrolyte membrane may include a solid electrolyte, wherein the solid electrolyte may include at least one selected from sulfide solid electrolytes, polymer solid electrolytes, and oxide solid electrolytes, and preferably includes only sulfide solid electrolytes. The sulfide solid electrolyte may include a lithium salt, wherein the lithium salt is an ionizable lithium salt, denoted as Li. + X - These lithium salts are not particularly limited and may include F. - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - , CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C -CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - As an anion.

[0039] Furthermore, sulfide-based solid electrolytes may include Li-PS-based glasses or Li-PS-based glass-ceramics, which contain sulfur and have the ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table. Non-limiting examples of these sulfide-based solid electrolytes include Li₂S-P₂S₅, Li₂S-LiI-P₂S₅, Li₂S-LiI-Li₂O-P₂S₅, Li₂S-LiBr-P₂S₅, Li₂S-LiCl-P₂S₅, Li₂S-Li₂O-P₂S₅, Li₂S-Li₃PO₄-P₂S₅, Li₂S-P₂S₅-P₂O₅, Li₂S-P₂S₅-SiS₂, Li₂S-P₂S₅-SnS, Li₂S-P₂S₅-Al₂S₃, Li₂S-GeS₂, and Li₂S-GeS₂-ZnS, and the sulfide-based solid electrolyte may contain one or more of these.

[0040] These solid electrolytes can be used as separators in typical lithium secondary batteries (i.e., electrically insulating the negative and positive electrodes while allowing lithium ions to pass through). On the other hand, all-solid-state batteries can be used as semi-solid-state batteries by incorporating liquid electrolytes as needed, in which case a separate polymer separator may be required.

[0041] An electrode stack according to one embodiment of the present invention may include a negative electrode (4). The negative electrode may include any negative electrode active material available in conventional all-solid-state batteries. For example, the negative electrode active material may include at least one selected from the group consisting of: carbon, such as anthracite carbon, graphitized carbon, etc.; metal composite oxides, such as Li x Fe2O3 (where 0≤x≤1), Li x WO2 (where 0≤x≤1), Sn x Me 1-x Me′ y O z(wherein Me is Mn, Fe, Pb or Ge; Me' is Al, B, P or Si, a Group 1, 2 or 3 element of the periodic table, or a halogen; 0<x≤1; 1≤y≤3; and 1≤z≤8) and other metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides, such as SnO, SnO₂, PbO, PbO₂, Pb₂O₃, Pb₃O₄, Sb₂O₃, Sb₂O₄, Sb₂O₅, GeO, GeO₂, Bi₂O₃, Bi₂O₄, Bi₂O₅, etc.; conductive polymers, such as polyacetylene; Li-Co-Ni based materials; titanium oxides; and lithium titanium oxides.

[0042] The electrode laminate according to one embodiment of the present invention may be in the form of an anode-free battery (anode-less battery).

[0043] When the electrode laminate is an anode-free battery, during initial battery fabrication, no lithium metal or only a small amount of lithium metal is present on the negative electrode current collector. However, during charging, metallic lithium precipitates between the negative electrode active material layer and the current collector to form a lithium metal layer. During discharging, the battery is driven by the mechanism in which metallic lithium is ionized and moves toward the positive electrode.

[0044] An anode-free battery may lack a negative electrode active material layer during initial fabrication. With reference to Figure 1 the electrode laminate therein, as shown in Figure 5 , initially no negative electrode active material is present on the negative electrode current collector. Instead, the lithium metal layer formed via charging acts as the negative electrode.

[0045] The negative electrode of an anode-free battery may include a structure comprising a negative electrode active material layer, and the negative electrode active material layer comprises a metal alloyable with lithium and a carbon material.

[0046] The thickness of the negative electrode active material layer is generally 1 μm to 100 μm, preferably 10 μm to 60 μm, specifically 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, but is not limited thereto.

[0047] The all-solid-state battery according to one embodiment of the present invention comprises composite separators (6, 7).

[0048] The composite separator (6, 7) comprises a separator layer (7) and a buffer layer (6) disposed on at least one surface of the separator layer. Preferably, the buffer layer (6) is formed on both surfaces of the separator layer (7).

[0049] In the all-solid-state battery according to one embodiment of the present invention, the composite separator (6, 7) may fix the electrode laminate.

[0050] The separator layer can contain any material commonly used in secondary batteries, preferably including a separator made of one or more materials selected from the group consisting of polyethylene (PE), polypropylene (PP), and resins made from blends of PE and PP.

[0051] In an all-solid-state battery according to one embodiment of the present invention, the positive current collector (1) may be located on the positive electrode and the composite separator (6, 7) of the electrode stack, while the negative current collector (5) may be located on the negative electrode and the composite separator (6, 7) of the electrode assembly.

[0052] In an all-solid-state battery according to one embodiment of the present invention, the buffer layer (6) may include at least one material selected from the group consisting of organosilicon, PTFE, polyurethane resin (PUR), polyolefin (PO) and polyamide (PA).

[0053] In one embodiment of the all-solid-state battery of the present invention, the thickness of the separator layer can be from 4 μm to 10 μm, preferably 5 μm or more, 6 μm or more, or 7 μm or more, and can be less than 9 μm, less than 8 μm, or less than 7 μm.

[0054] In one aspect of the all-solid-state battery of the present invention, the thickness of the buffer layer (6) can be from 10 μm to 50 μm, preferably more than 15 μm, more than 20 μm, more than 25 μm, or more than 30 μm, and can be less than 45 μm, less than 40 μm, less than 35 μm, or less than 30 μm.

[0055] In an all-solid-state battery according to one embodiment of the present invention, the buffer layer (6) can contact the electrode stack to fix the electrode assembly.

[0056] In an all-solid-state battery according to one embodiment of the present invention, the electrode stack including a positive electrode (2), an electrolyte membrane (3) and a negative electrode (4) can have various structures.

[0057] Specifically, the electrode stack can be a single cell or a dual cell.

[0058] In an all-solid-state battery according to one embodiment of the present invention, the electrode stack may have Figure 1 The single-sided electrode structure is shown. In an all-solid-state battery according to one embodiment of the present invention, a single-sided electrode can refer to an electrode on only one side of the current collector (foil).

[0059] In an all-solid-state battery according to one embodiment of the present invention, the electrode stack may have Figure 2The C-type structure is shown. In an all-solid-state battery according to one embodiment of the present invention, the C-type structure can refer to the following structure: an electrode with a positive electrode layer formed on both sides of the current collector (foil) is located at the center, and an electrolyte layer is provided on both sides of the electrode and an electrode with a negative electrode layer on one side of the current collector (foil).

[0060] In an all-solid-state battery according to one embodiment of the present invention, the electrode stack may have Figure 3 The A-type structure is shown. In an all-solid-state battery according to one embodiment of the present invention, the A-type structure can refer to the following structure: an electrode with a negative electrode layer formed on both sides of the current collector (foil) is located at the center, and an electrolyte layer is provided on both sides of the electrode and an electrode with a positive electrode layer on one side of the current collector (foil).

[0061] In an all-solid-state battery according to one embodiment of the present invention, the electrode stack may have Figure 4 The multi-cell battery cell shown is an example of a cell that utilizes more bifacial electrodes than a typical single-cell battery cell to increase energy density in an all-solid-state battery according to one embodiment of the present invention. For example, as... Figure 4 As shown, it can refer to the following structure: an electrode with a negative electrode layer formed on both sides of the current collector (foil) is located in the center, an electrolyte layer is provided on both sides of the electrode and an electrode with a positive electrode layer provided on both sides of the current collector (foil), and then an electrode with a negative electrode layer formed on one side of the current collector (foil) is provided at the outermost edge.

[0062] The present invention also provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of such devices include, but are not limited to: power tools powered by an electric motor; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; electric two-wheelers, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; power storage systems; and so on.

[0063] Although the invention has been described above with limited examples and figures, it is not limited thereto, and those skilled in the art can make various modifications and variations within the scope of the technical concept of the invention and the equivalents of the patent claims set forth below.

[0064] [Figure Labels]

[0065] 1: Positive current collector

[0066] 2: Positive electrode

[0067] 3: Electrolyte membrane

[0068] 4: Negative electrode

[0069] 5: Negative electrode current collector

[0070] 6: Buffer layer

[0071] 7: Diaphragm layer

Claims

1. An all-solid-state battery, comprising: An electrode stack comprising a positive electrode, an electrolyte membrane, and a negative electrode; and A composite diaphragm, wherein the composite diaphragm wraps around the electrode stack in a zigzag pattern, positioning the electrode stack at the folded portion. The composite membrane includes a membrane layer and a buffer layer disposed on at least one surface of the membrane layer.

2. The all-solid-state battery as described in claim 1, wherein, The diaphragm layer comprises any one of the following materials selected from the group consisting of polyethylene (PE), polypropylene (PP), and resins made from blends of PE and PP.

3. The all-solid-state battery as described in claim 1, wherein, The buffer layer comprises any one of the following materials selected from the group consisting of silicone, PTFE, polyurethane resin (PUR), polyolefin (PO), and polyamide (PA).

4. The all-solid-state battery as described in claim 1, wherein, The thickness of the diaphragm layer is 4 μm to 10 μm.

5. The all-solid-state battery as described in claim 1, wherein, The thickness of the buffer layer is 10 μm to 50 μm.

6. The all-solid-state battery as described in claim 1, wherein, The buffer layer contacts the electrode stack to fix the electrode assembly.

7. The all-solid-state battery as described in claim 1, wherein, The electrode stack is a single cell or a dual cell.

8. The all-solid-state battery as described in claim 1, wherein, The electrode stack is in the form of an anode-free structure.

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