All-solid-state battery

Abstract

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

Description

All-solid-state battery

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0102266, filed August 4, 2023, the entire contents of which are incorporated herein by reference.

[0002] 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 a protective layer is additionally disposed on the periphery of an electrode laminate included within the all-solid-state battery, thereby preventing cracking of an electrolyte layer due to tension of a separator.

[0003] With the explosive growth in technological development and demand for mobile devices and automobiles, more research is being conducted on secondary batteries featuring high energy density, discharge voltage, and excellent output stability. Examples of these secondary batteries include lithium-based secondary batteries, such as lithium-sulfur batteries, lithium-ion batteries, and lithium-ion polymer batteries. Furthermore, these secondary batteries can be categorized into cylindrical, prismatic, and pouch-shaped types, with interest and demand for pouch-shaped battery cells steadily increasing. Pouch-shaped battery cells can be stacked with high density, have high energy density per unit weight, are inexpensive, and are easily modified. Therefore, pouch-shaped battery cells can be manufactured in shapes and sizes suitable for various mobile devices and automobiles.

[0004]

[0005] A pouch-type battery cell of this type generally has a structure in which one or more unit cells including a positive electrode, a negative electrode, and a separator interposed therebetween are stacked (i.e., an electrode assembly or stack cell). The electrode assembly can be housed in a battery case and then an electrolyte can be injected, or a solid electrolyte can be provided in the electrode assembly from the beginning to be manufactured (i.e., an all-solid-state battery).

[0006] 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.

[0007] 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.

[0008] In this WIP process, as shown in Fig. 1, there was a problem that cracks occurred in the electrolyte layer even with a small impact after WIP.

[0009] In particular, when stacking is performed in a Z-stacking manner using a separator as shown in Fig. 2, there is a problem that cracks occur in the electrolyte layer due to the tension of the separator. Therefore, it is necessary to search for a novel all-solid-state battery having a structure that does not cause cracks in the electrolyte layer while isotropically pressurizing the cell.

[0010] (Patent Document 1) Korean Patent Publication No. 10-2016-0131681

[0011] 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 capable of preventing the occurrence of cracks in the electrolyte layer having a large electrode dash size due to the separator when applying Z-stacking for unit cell stacks, in which the electrode / electrolyte layer becomes hardened by the WIP process used when manufacturing a sulfide-based all-solid-state battery.

[0012] In order to achieve the above object, in one embodiment according to the present disclosure, an all-solid-state battery is provided, which includes an electrode assembly including an electrode laminate including a positive electrode, an electrolyte membrane, and a negative electrode; and a pair of protective layers positioned on the upper and lower outer surfaces of the electrode laminate; and a separator that wraps the electrode assembly in a zigzag pattern so that the electrode assembly is positioned at a folded portion.

[0013] In addition, an all-solid-state battery is provided, which includes any one material selected from the group consisting of PI, PP, and PET as the protective layer.

[0014] In addition, an all-solid-state battery is provided in which the outer surface of the protective layer and the electrode laminate are bonded through a primary coating layer or a binder layer.

[0015] In addition, the binder layer provides an all-solid-state battery including any one material selected from the group consisting of PVDF, PO, and PUR.

[0016] Additionally, the length of the protective layer provides an all-solid-state battery longer than the positive and negative electrodes.

[0017] In addition, an all-solid-state battery is provided in which a positive electrode current collector is positioned on the positive electrode and separator of the electrode assembly, and a negative electrode current collector is positioned on the negative electrode and separator of the electrode assembly.

[0018] Additionally, the separator provides an all-solid-state battery that fixes the electrode assembly.

[0019] An all-solid-state battery according to one embodiment of the present disclosure has the effect of preventing cracks in the electrolyte layer due to tension of the separator by additionally arranging a protective layer on the outer surface of the electrode stack (positive electrode, electrolyte membrane, negative electrode).

[0020] Figure 1 is a drawing showing the structure of an all-solid-state battery according to conventional technology.

[0021] Figure 2 is a drawing showing a laminated structure of an all-solid-state battery according to conventional technology.

[0022] FIG. 3 is a drawing showing the cell structure of an all-solid-state battery according to one embodiment of the present disclosure.

[0023] FIG. 4 is a drawing showing a laminated structure of an all-solid-state battery according to one embodiment of the present disclosure.

[0024] FIG. 5 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

[0025] FIG. 6 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

[0026] FIG. 7 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

[0027] FIG. 8 is a drawing showing a laminated structure of an all-solid-state battery according to another embodiment of the present disclosure.

[0028] Hereinafter, the present disclosure will be described in more detail to help understand the present disclosure.

[0029] 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.

[0030] 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.

[0031] 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.

[0032]

[0033] FIG. 3 is a drawing showing a unit cell of an all-solid-state battery according to one embodiment of the present disclosure.

[0034] Referring to FIG. 3, an all-solid-state battery according to one embodiment of the present disclosure includes an electrode assembly including an electrode laminate including a positive electrode, an electrolyte membrane, and a negative electrode; and a pair of protective layers positioned on the upper and lower outer surfaces of the electrode laminate; and a separator that wraps the electrode assembly in a zigzag pattern so that the electrode assembly is positioned at a folded portion.

[0035]

[0036] An electrode assembly of 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).

[0037] An electrode laminate according to one embodiment of the present disclosure may include an anode (2).

[0038] According to one embodiment of the present disclosure, a cathode 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 cathode active material, a solid electrolyte, a conductive material, and a binder. Among these, as a cathode active material, as long as it can be used as a cathode active material of an all-solid-state battery, it can be used without limitation. The cathode active material may be a lithium transition metal oxide containing one or more transition metals. For example, the cathode active material may be LiCoO2, LiNiO2, LiMnO2, Li2MnO3, LiMn2O4, Li(Ni a Co b Mn c )O2(0 <a<1, 0<b<1, 0<c<1, a+b+c=1), LiNi 1-y Co y O2(O <y<1), LiCo 1-y Mn y O2, LiNi 1-y Mn y O2(O <y<1), Li(Ni a Co b Mn c )O4(0 <a<2, 0<b<2, 0<c<2, a+b+c=2), LiMn 2-z Ni z O4(0 <z<2), LiMn 2-z Co z O4(0 <z<2) 및 이의 조합으로 이루어진 군으로부터 선택되는 것일 수 있다.

[0039] 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.

[0040] 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 is an ionizable lithium salt such as Li + X - It can be expressed as . The anion of this lithium salt is not particularly limited, but 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 - Examples include:

[0041] 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 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 include any one or more thereof.

[0042] 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.

[0043] 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.; Li x Fe2O3(0≤x≤1), Li x WO2(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, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni계 재료; 티타늄 산화물; 리튬 티타늄 산화물; 등에서 선택된 어느 하나 이상을 포함한 것일 수 있다.

[0044]

[0045] An electrode assembly of an all-solid-state battery according to one embodiment of the present disclosure includes a protective film (6).

[0046] The electrode / electrolyte layers can be hardened by the WIP process used when manufacturing a sulfide-based all-solid-state battery. When the unit cells hardened in this way are stacked using the Z-stacking method, the tension of the separator surrounding the unit cells can directly act on the electrode / electrolyte layers. At this time, the tension of the separator is concentrated on the electrolyte layer, which is larger than the electrode, and cracks in the electrolyte layer may occur due to the separator. At this time, since the protective film is arranged on the periphery of the electrode laminate, even if the separator applies strong pressure while wrapping the electrode assembly, direct pressure cannot be applied to the electrolyte membrane within the electrode assembly. Accordingly, the electrode assembly of the all-solid-state battery according to one embodiment of the present disclosure can prevent cracks in the electrolyte membrane by including the protective film.

[0047] For the above function, the protective layer of the all-solid-state battery according to one embodiment of the present disclosure can be used without any special limitation as long as it is a material that does not deform at a temperature of 80°C, and for example, can include any one material selected from the group consisting of PI, PP, and PET.

[0048] In an all-solid-state battery according to one embodiment of the present disclosure, the protective layer and the exterior of the electrode laminate can be bonded through a primary coating layer or a binder layer.

[0049] In an all-solid-state battery according to one embodiment of the present disclosure, the primary coating layer may be a primary coating layer commonly used in the industry.

[0050] In an all-solid-state battery according to one embodiment of the present disclosure, the binder layer may be made of any material without special limitation as long as it has adhesiveness, and may include, for example, any one material selected from the group consisting of PVDF, PO, and PUR.

[0051] In an all-solid-state battery according to one embodiment of the present disclosure, the length of the protective layer may be longer than that of the positive and negative electrodes. Specifically, as shown in FIG. 4, since the length of the protective layer is longer than that of the positive and negative electrodes, the separator prevents direct pressure from being applied to the electrodes or the electrolyte membrane. Accordingly, cracking of the electrolyte membrane can be prevented.

[0052] In an all-solid-state battery according to one embodiment of the present disclosure, the lengths of the pair of protective layers may be identical. Specifically, as shown in FIG. 4, if the lengths of the pair of protective layers are identical, the separator is longer than the positive and negative electrodes, preventing the separator from exerting direct pressure on the electrodes or the electrolyte membrane. Consequently, cracking of the electrolyte membrane can be prevented.

[0053]

[0054] An all-solid-state battery according to one embodiment of the present disclosure includes a separator (7).

[0055] In an all-solid-state battery according to one embodiment of the present disclosure, the separator can secure the electrode assembly. There is no particular limitation on the separator as long as it is a general separator used in secondary batteries, but preferably, a separator using at least one material selected from the group consisting of polyethylene (PE), polypropylene (PP), and a resin blended with PE and PP can be used.

[0056] 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 separator of the electrode assembly, and a negative electrode current collector (5) may be positioned on the negative electrode and separator of the electrode assembly.

[0057] 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.

[0058] In an 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. 5. In an all-solid-state battery according to one embodiment of the present disclosure, a single-sided electrode may mean an electrode in which an electrode layer is formed on only one side of a current collector (foil).

[0059] 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. 6. 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.

[0060] 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. 7. 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.

[0061] 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 illustrated in FIG. 8. 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 illustrated in FIG. 8, 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.

[0062]

[0063] 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.

[0064] 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.

[0065] [Explanation of symbols]

[0066] 1: Positive current collector

[0067] 2: Bipolar

[0068] 3: Electrolyte membrane

[0069] 4: Cathode

[0070] 5: Negative current collector

[0071] 6: Protective layer

[0072] 7: Membrane

Claims

1. An electrode assembly comprising an electrode laminate including a positive electrode, an electrolyte membrane, and a negative electrode; and a pair of protective layers positioned on the upper and lower outer surfaces of the electrode laminate; A separator comprising a zigzag-wrapped electrode assembly, wherein the electrode assembly is positioned at the folded portion. All-solid-state battery.

2. In paragraph 1, The protective layer is characterized in that it comprises any one material selected from the group consisting of PI, PP and PET. All-solid-state battery.

3. In paragraph 1, The outer surface of the above protective layer and electrode laminate is bonded through a primary coating layer or binder layer. All-solid-state battery.

4. In paragraph 1, The binder layer is characterized in that it comprises any one material selected from the group consisting of PVDF, PO and PUR. All-solid-state battery.

5. In paragraph 1, The length of the above protective layer is characterized by being longer than that of the anode and cathode. All-solid-state battery.

6. In paragraph 1, A positive electrode current collector is positioned on the positive electrode and separator of the above electrode assembly, The above electrode assembly is characterized in that a negative electrode current collector is positioned on the negative electrode and separator. All-solid-state battery.

7. In paragraph 1, The above separator is characterized in that it fixes the electrode assembly. All-solid-state battery.

Images