A positive electrode sheet and a full solid-state battery

Abstract

This invention provides a positive electrode sheet and an all-solid-state battery. The positive electrode sheet includes a buffer assembly, which includes a buffer frame and a buffer layer located on at least one side of the buffer frame. The buffer assembly is disposed on at least one side of the positive current collector and is circumferentially disposed at the edge of the positive active material layer. The buffer layer is disposed at the contact position between the buffer frame and the positive electrode tab, and the buffer layer is in contact with the positive electrode tab. The ratio of the length of the buffer layer in a first direction to the length of the positive electrode tab in a first direction is 52:(1~50). The buffer assembly provided by this invention not only improves the interfacial contact performance between the electrode and the solid electrolyte, avoiding short circuits due to deformation of the positive and negative electrodes and effectively improving battery safety, but also provides space to accommodate the tab during subsequent isostatic pressing, reducing the risk of tab breakage and improving the battery's yield and product quality.

Description

Technical Field

[0001] This utility model belongs to the field of battery material technology, specifically relating to a positive electrode and an all-solid-state battery. Background Technology

[0002] All-solid-state batteries are a battery technology that uses solid electrolytes to replace traditional separators and liquid electrolytes. They have significant advantages such as high energy density, high safety and long life, making them a promising technology for applications in new energy vehicles, energy storage systems and consumer electronics. However, solid electrolytes still have some problems in application, such as: (1) the mechanical strength of solid electrolyte membranes is usually lower than that of traditional separators, which makes them prone to short circuits during battery operation; (2) unlike the solid-liquid interface contact in liquid batteries, the solid-solid interface contact in all-solid-state batteries requires higher pressure to achieve good interface contact and ion transport performance.

[0003] Specifically, during the assembly and operation of all-solid-state batteries, the different material properties of the positive electrode, solid electrolyte, and negative electrode lead to variations in their mechanical behavior under external pressure. For example, when a large pressure is applied to the cell, the edges of the positive electrode are prone to collapse and deformation, resulting in porosity between the electrode and the solid electrolyte. This can further cause the electrode to crack or even shatter under pressure, ultimately leading to a short circuit. Furthermore, the interface between the solid electrolyte and the positive and negative electrodes is typically a hard contact, which easily leads to stress accumulation and cracks in the electrode and electrolyte layers. The dimensional differences between the positive and negative electrodes can also generate significant shear stress at the edges of the layers. This stress can cause the electrode edges to tear or even penetrate the solid electrolyte, creating defects in the all-solid-state battery structure and further exacerbating the risk of short circuits.

[0004] In addition to the issues mentioned above, the tabs of all-solid-state batteries also face several challenges. Specifically, variations in tab thickness directly affect the current density and temperature distribution of the battery, leading to aging and failure. Furthermore, uneven tab thickness can cause them to be subjected to greater localized forces during battery assembly and operation, potentially resulting in breakage and consequently reducing the yield and safety of all-solid-state batteries.

[0005] Therefore, optimizing the interfacial contact between the electrode and the solid electrolyte, and ensuring good structural stability and integrity of the electrode and tab, thereby comprehensively improving the safety and cycle life of all-solid-state batteries, is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0006] To address the shortcomings of existing technologies and to solve the technical problems of poor interfacial performance between the electrode and the solid electrolyte membrane, as well as the high assembly stress in all-solid-state batteries that makes the electrodes and tabs prone to deformation or even breakage, this invention aims to provide a positive electrode sheet and an all-solid-state battery that ensure sufficient strength so that the electrodes maintain their shape at high temperatures, preventing short circuits due to deformation of the positive and negative electrodes and effectively improving the safety of all-solid-state batteries. Simultaneously, the compression deformation of the buffer layer material during the subsequent isostatic pressing process provides space to accommodate the tabs, reducing the risk of tab breakage and improving the yield rate and product quality of all-solid-state batteries.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, wherein a positive electrode tab is provided on the positive current collector.

[0009] The positive electrode includes a buffer assembly, which includes a buffer frame and a buffer layer located on at least one side of the buffer frame;

[0010] The buffer component is disposed on at least one side of the positive electrode current collector, and the buffer component is circumferentially disposed at the edge of the positive electrode active material layer;

[0011] The buffer layer is disposed at the contact position between the buffer frame and the positive electrode tab, and the buffer layer is in contact with the positive electrode tab. The ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction is 52:(1~50).

[0012] As a further preferred embodiment, the ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction is 52:(25~50).

[0013] As a preferred embodiment, the thickness of the buffer frame satisfies the following relationship: 5μm≤D1≤(D2-9)μm, where D1 is the thickness of the buffer frame in μm and D2 is the thickness of the positive electrode active material layer in μm.

[0014] As a preferred embodiment, the buffer layer is an elastic buffer layer.

[0015] As a preferred embodiment, the thickness of the buffer layer is 10μm to 150μm.

[0016] As a further preferred embodiment, the thickness of the buffer layer is 20μm to 130μm.

[0017] As a preferred embodiment, the deformation thickness of the buffer component is greater than half the thickness of the positive electrode tab.

[0018] As a preferred embodiment, the deformation thickness of the buffer component is 5μm to 20μm.

[0019] As a preferred embodiment, the total thickness of the buffer component after compression is less than or equal to the thickness of the positive electrode active material layer.

[0020] This utility model also provides an all-solid-state battery, which includes a positive electrode, a negative electrode and a solid electrolyte membrane, wherein the positive electrode includes the aforementioned positive electrode.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides a positive electrode sheet. By adjusting the structure and composition of the buffer assembly, the interface between the positive electrode material and the solid electrolyte can be made more stable. Furthermore, while ensuring good structural stability of the electrodes and tabs, it can further alleviate the short-circuit problem caused by electrode size mismatch during isostatic pressing of all-solid-state batteries, thereby reducing the risk of short circuits. Specific features are as follows:

[0023] (1) The buffer component provided by this utility model can fill the interfacial gap between the positive electrode material and the solid electrolyte membrane, improve the interfacial contact between the positive electrode material and the solid electrolyte membrane, reduce the interfacial impedance, reduce the risk of short circuit, and improve the cycle stability and safety of the all-solid-state battery.

[0024] (2) The buffer component provided by this utility model has both suitable flexibility and mechanical strength, which effectively alleviates the volume change of the positive electrode material during the charging and discharging process, thereby preventing the electrode from cracking due to volume expansion and improving the structural stability of the all-solid-state battery.

[0025] (3) The buffer component provided by this utility model can not only prevent the edge of the electrode from collapsing and deforming during the isostatic pressing process, causing the battery to short-circuit and fail, but also avoid the tab breakage and improve the yield of all-solid-state battery manufacturing. Attached Figure Description

[0026] Figure 1 A schematic diagram of the structure of the all-solid-state battery made from the buffer component provided by this utility model.

[0027] Explanation of reference numerals in the attached figures:

[0028] Among them, 10 is the positive electrode, 20 is the buffer component, 30 is the negative electrode, 110 is the positive electrode tab, 210 is the buffer layer, and 310 is the negative electrode tab. Detailed Implementation

[0029] To make the technical problem solved by this utility model, the technical solution adopted, and the technical effect achieved clearer, the technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] It should be understood that in the description of this utility model, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Furthermore, the terms "first" and "second" are merely used for distinction in description and have no special meaning. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] Currently, all-solid-state batteries face two main problems in their application: Firstly, the use of solid electrolytes instead of liquid electrolytes in all-solid-state batteries results in poor interfacial compatibility between the electrodes and the solid electrolyte, which can easily lead to voids or poor contact, thus affecting the electrochemical performance of the battery.

[0033] On the other hand, in the production process of all-solid-state batteries, significant pressure needs to be applied to the electrode components to achieve solid-solid interface bonding and maintain structural stability. Currently, this significant pressure is mainly achieved using isostatic pressing. Therefore, during isostatic pressing production, the electrodes and tabs are subjected to high pressure, causing deformation or rupture, which can lead to battery short circuits and reduce the yield of finished batteries.

[0034] To solve the above problems, such as Figure 1 As shown, in one embodiment of the present invention, a positive electrode sheet 10 is provided, including a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector. A positive electrode tab 110 is provided on the positive electrode current collector.

[0035] The positive electrode 10 includes a buffer assembly 20, which includes a buffer frame and a buffer layer 210 located on at least one side of the buffer frame;

[0036] The buffer component 20 is disposed on at least one side of the positive electrode current collector, and the buffer component 20 is circumferentially disposed at the edge of the positive electrode active material layer;

[0037] The buffer layer 210 is disposed at the contact position between the buffer frame and the positive electrode tab 110, and the buffer layer 210 is attached to the positive electrode tab 110. The ratio of the length of the buffer layer 210 in the first direction to the length of the positive electrode tab 110 in the first direction is 52:(1~50).

[0038] This invention introduces a buffer component with a specific structure into the positive electrode sheet, which facilitates the formation of a tightly bonded interface and avoids the formation of voids and pores at the interface, thereby improving the safety and cycle performance of the all-solid-state battery. Furthermore, this buffer component also provides additional support and further regulates the ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction, ensuring that the electrode sheet and tab maintain a good shape at high temperatures. This prevents abnormalities such as short circuits at the positive and negative electrode connections and tab breakage caused by the collapse and deformation of the electrode assembly edges due to isostatic pressure, thus improving the production yield of the electrode assembly.

[0039] Furthermore, the ratio of the length of the buffer layer 210 in the first direction to the length of the positive electrode tab 110 in the first direction is 52:(1-50), preferably 52:(25-50), for example, it can be 52:1, 26:1, 13:1, 26:3, 52:9, 52:15, 13:5, 52:25, 52:35, 52:41, 52:41, 52:47, 13:12, or 26:25, etc. The above values ​​are only examples and are not limitations.

[0040] In this embodiment, the tensile strength of the buffer frame is 130MPa to 170MPa, for example, it can be 130MPa, 140MPa, 150MPa, 160MPa or 170MPa. The above values ​​are only examples and are not limitations.

[0041] In this embodiment, the elastic modulus of the buffer frame is 2000MPa to 6000MPa, for example, it can be 2000MPa, 3000MPa, 4000MPa, 5000MPa or 6000MPa. The above values ​​are only examples and are not limitations.

[0042] In this embodiment, the buffer frame can withstand a high pressure of 100 MPa during the nail puncture test.

[0043] In this invention, by adjusting the specific physical properties of the buffer frame, it is made to have high mechanical strength and good buffering performance, thereby helping to improve the overall performance and structural stability of the all-solid-state battery.

[0044] In this embodiment, the thickness of the buffer frame satisfies the following relationship: 5μm≤D1≤(D2-9)μm, where D1 is the thickness of the buffer frame in μm and D2 is the thickness of the positive electrode active material layer in μm.

[0045] In this embodiment, the buffer border can be a two-layer or multi-layer structure, and the composition of each layer can be the same or different. This utility model does not limit this.

[0046] In this embodiment, the material of the buffer frame is selected from any one or a combination of at least two of polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyimide (PI), or polycarbonate (PC).

[0047] In this invention, by selecting the aforementioned high-temperature resistant hard material, the stability of the all-solid-state battery at high temperatures is improved.

[0048] In this embodiment, the buffer layer 210 is an elastic buffer layer, and the material of the elastic buffer layer is selected from functional materials with elastic deformation.

[0049] Specifically, the functional material with elastic deformation is selected from any one or a combination of at least two of thermoplastic polyurethane elastomer (TPU), polydimethylsiloxane (PDMS), polyolefin elastomer (POE), ethylene-vinyl acetate elastomer (EVA), polyurethane elastomer (PU), polyethylene (PE), polypropylene (PP), or nonwoven fabric.

[0050] This invention uses a functional material with controllable deformation properties, which provides dynamic accommodation space for the tabs through elastic deformation, preventing the tabs from breaking due to uneven stress, thereby helping to improve the overall performance and structural stability of the all-solid-state battery.

[0051] In this embodiment, the tensile strength of the elastic buffer layer is 10MPa to 150MPa, for example, it can be 10MPa, 20MPa, 50MPa, 80MPa, 100MPa, 120MPa or 150MPa. The above values ​​are only examples and are not limitations.

[0052] In this embodiment, the elastic modulus of the elastic buffer layer is 10MPa to 1000MPa, for example, it can be 10MPa, 20MPa, 50MPa, 80MPa, 100MPa, 200MPa, 500MPa, 800MPa or 1000MPa. The above values ​​are only examples and are not limitations.

[0053] In this invention, by adjusting the specific physical properties of the elastic buffer layer to give it suitable elasticity and mechanical strength, it can not only play a good buffering role, but also provide a space for the tabs, thereby improving the reliability and safety of the all-solid-state battery.

[0054] In this embodiment, the thickness of the buffer layer 210 is 10μm to 150μm, preferably 20μm to 130μm, for example, it can be 10μm, 12μm, 15μm, 18μm, 20μm, 50μm, 80μm, 100μm, 120μm, 130μm or 150μm, etc. The above values ​​are only examples and are not limiting.

[0055] In this embodiment, the deformation thickness of the buffer component is greater than half the thickness of the positive electrode tab.

[0056] In this embodiment, the deformation thickness of the buffer component is 5μm to 20μm, for example, it can be 5μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, etc. The above values ​​are only examples and are not limitations.

[0057] In this invention, by adjusting the thickness of the buffer frame and the buffer layer to satisfy the relationship described above, the main purpose is to ensure that the thickness of the buffer assembly is less than or equal to the thickness of the positive electrode active material layer after subsequent pressing, so that the buffer assembly is within the deformation range and can accommodate the thickness of the tab.

[0058] In this embodiment, the thickness of the buffer layer at the contact position between the buffer frame and the positive electrode tab can be the same as or different from the thickness of the remaining buffer layers around the positive electrode active material layer, and the composition can be the same as or different. This utility model does not impose any restrictions on this.

[0059] In this embodiment, the outer side length of the buffer frame can be greater than, equal to or less than the outer side length of the negative electrode 30, and this utility model does not impose any restrictions on this.

[0060] In this embodiment, the thickness of the positive electrode current collector is 10μm to 20μm, for example, it can be 10μm, 12μm, 15μm, 18μm or 20μm, etc. The above values ​​are only examples and are not limitations.

[0061] In this embodiment, the compressive strength of the positive current collector is 100MPa to 200MPa, for example, it can be 100MPa, 120MPa, 150MPa, 180MPa or 200MPa. The above values ​​are only examples and are not limitations.

[0062] In this embodiment, the total thickness of the buffer component after compression is less than or equal to the thickness of the positive electrode active material layer.

[0063] This invention also provides a method for preparing the above-mentioned positive electrode sheet, the method comprising the following steps:

[0064] By combining at least one side of the buffer border with the buffer layer, a buffer component is obtained;

[0065] A positive current collector with a positive active material layer on at least one side is pressed together with a buffer assembly, so that the inner wall of the buffer frame is in close contact with the edge of the positive active material layer, and the buffer layer is attached to the surface of the positive current collector or the positive electrode tab, thus obtaining a positive electrode sheet.

[0066] In this embodiment, the pressing temperature is 75℃~85℃, for example, it can be 75℃, 78℃, 80℃, 82℃ or 85℃, etc. The above values ​​are only examples and are not limited.

[0067] In this embodiment, the pressure for the pressing process is 2MPa to 5MPa, for example, it can be 2MPa, 3MPa, 4MPa or 5MPa. The above values ​​are only examples and are not limitations.

[0068] In this embodiment, the pressing process includes, for example, hot pressing.

[0069] In this embodiment, under a pressure of 2MPa to 5MPa, the buffer component of the positive electrode sheet is within a suitable deformation range, which can better accommodate the positive electrode tab.

[0070] In this embodiment, the pressing time is 15 min to 25 min, for example, 15 min, 18 min, 20 min, 22 min, or 25 min. The above values ​​are only examples and are not limitations.

[0071] In this embodiment, after the pressing process is completed, the total thickness of the buffer assembly is less than or equal to the thickness of the positive electrode active material layer.

[0072] In another embodiment of the present invention, an all-solid-state battery is provided, which includes a positive electrode, a negative electrode and a solid electrolyte membrane, wherein the positive electrode includes the aforementioned positive electrode.

[0073] It is understood that this invention does not impose any particular limitations on the positive electrode current collector material, as long as it is conductive and does not cause chemical changes in the battery. For example, the positive electrode current collector may include, but is not limited to, any one of aluminum, nickel, or stainless steel, such as aluminum foil.

[0074] It is understood that the present invention does not impose any particular limitation on the shape of the positive current collector. For example, the shape of the positive current collector includes, but is not limited to, metal foil, metal grid, metal mesh, etc.

[0075] It is understood that the positive electrode active material is a compound that reversibly inserts and deinserts lithium, and the positive electrode active material in this invention can be any positive electrode active material known in the art. For example, the positive electrode active material can be selected from lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate, lithium iron phosphate, lithium titanate, or lithium-rich manganese elastic base materials, etc.

[0076] In this embodiment, the negative electrode sheet 30 includes a negative electrode current collector and a negative electrode active material layer covering at least one side surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a binder, and a conductive agent. A negative electrode tab 310 is provided on the negative electrode current collector.

[0077] It is understood that this invention does not impose any particular limitations on the negative electrode current collector material, as long as it is conductive and does not cause chemical changes in the battery. For example, the negative electrode current collector may include, but is not limited to, any one of copper, nickel, or stainless steel, such as copper foil.

[0078] It is understood that the present invention does not impose any particular limitation on the shape of the negative electrode current collector. For example, the shape of the negative electrode current collector includes, but is not limited to, metal foil, metal grid, metal mesh, etc.

[0079] It is understood that the negative electrode active material is a compound that reversibly inserts and deinserts lithium, and the negative electrode active material in this invention can be any negative electrode active material known in the art. For example, the negative electrode active material can be selected from natural graphite, artificial graphite, hard carbon, soft carbon, silicon-based materials, titanium-based materials, tin-based materials, and metallic lithium, etc.

[0080] It is understood that this invention does not specifically limit the type of conductive agent; the positive electrode active material layer and the negative electrode active material layer can choose the same conductive agent or different conductive agents. Exemplary examples include at least one of carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Examples include natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, acetylene black, carbon nanotubes, carbon nanofibers, polyaniline, polythiophene, polyacetylene, polypyrrole, or poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc.

[0081] It is understood that this utility model does not specifically limit the type of binder. Any binder capable of bonding and maintaining the active material, enhancing the contact between the active material and the conductive agent, and between the active material and the current collector, thereby stabilizing the electrode structure, without departing from the concept of this utility model, is within the protection scope of this utility model. The positive electrode active material layer and the negative electrode active material layer may use the same binder or different binders. For example, thermoplastic resins or thermosetting resins are included. Examples include polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, etc.

[0082] In this embodiment, the solid electrolyte membrane may also include, but is not limited to, polymer solid electrolytes, oxide solid electrolytes, or sulfide solid electrolytes.

[0083] In specific applications, sulfide solid electrolytes can be selected from: Li2S-P2S5, Li2S-P2S5-MS. x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li10.35 Ge 1.35 P 1.65 S 12 、Li 3.25 Ge 0.25 P 0.75 S4、Li 10 SnP2S 12 、Li 10 SiP2S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 、(1-x)P2S 5-x Li2S (where 0.5 ≤ x ≤ 0.7) or at least one of them.

[0084] In specific applications, the halide solid electrolyte can be selected from: Li2CdC l4 、Li2MgC l4 、Li2Cd I4 、Li2ZnI4、Li3OCl、LiI、Li5ZnI4、Li3OCl 1-x Br x (where 0 < x < 1) or at least one of them.

[0085] In specific applications, the oxide solid electrolyte can be selected from: perovskite type, garnet type, LISICON type, NASICON type. Among them, the perovskite type solid electrolyte material is preferably LLTO (lithium lanthanum titanate, Li 0.33 La 0.56 TiO3), the garnet type solid electrolyte material is preferably LLZO (lithium lanthanum zirconate, Li7La3Zr2O 12 ), the NASICON (sodium superionic conductor) type solid electrolyte material is preferably lithium aluminum titanium phosphate (LATPLi 1.3 Al 0.3 Ti 1.7 (PO4)3) or at least one of them.

[0086] In this embodiment, the above solid electrolyte can be used as a reduction-resistant layer material. The reduction-resistant layer can be provided on the solid electrolyte layer, can be provided on the negative electrode layer, or can be provided separately between the solid electrolyte layer and the negative electrode layer.

[0087] Furthermore, the above solid electrolyte material is used in combination with a reduction-resistant layer material and a lithium metal negative electrode. The above solid electrolyte material has high reduction resistance and is characterized by being stable to Li and having high ionic conductivity, which can optimize the performance of the lithium metal negative electrode and promote the application of the lithium metal negative electrode and the development of high-energy lithium metal batteries.

[0088] For example, the present invention also provides a method for preparing the above-mentioned all-solid-state battery, the method comprising the following steps:

[0089] By combining the above-mentioned positive electrode, solid electrolyte membrane and negative electrode, an all-solid-state battery is obtained.

[0090] In this embodiment, the composite treatment includes isostatic pressing.

[0091] The embodiments of this utility model do not impose specific limitations on the manufacturing process of all-solid-state batteries, and can be applied to battery structures such as wound batteries (e.g., cylindrical batteries), stacked batteries (e.g., prismatic batteries, pouch batteries) and other composite structure batteries (e.g., bipolar batteries, modular batteries).

[0092] The embodiments of this utility model are applicable to any tab structure, including but not limited to traditional monopole, multipole, composite, cut tab, and multilayer tab. This utility model is applicable to both monopole and multipole designs. For specially designed tab structures (with complex shapes formed through cutting and angle optimization), the buffer components can be adjusted and optimized according to specific circumstances.

[0093] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0094] Example 1

[0095] This embodiment provides a positive electrode 10, including an aluminum foil current collector and a positive electrode active material layer disposed on one side of the aluminum foil current collector. A positive electrode tab 110 is provided on the aluminum foil current collector, and the thickness of the positive electrode active material layer is 180 μm.

[0096] The positive electrode 10 also includes a buffer assembly 20, which includes a buffer frame and a buffer layer 210 located on one side of the buffer frame. The buffer frame is disposed on one side of the aluminum foil current collector and is circumferentially disposed at the edge of the positive electrode active material layer; the buffer layer 210 is disposed at the contact position between the buffer frame and the positive electrode tab 110 and is attached to the positive electrode tab 110.

[0097] The buffer frame is made of polyethylene terephthalate (PET), with a tensile strength of 150 MPa, an elastic modulus of 4000 MPa, and a thickness of 115 μm. The buffer layer 210 is made of thermoplastic polyurethane elastomer (TPU), with a melting point of 150℃, a tensile strength of 80 MPa, an elastic modulus of 500 MPa, and a thickness of 100 μm.

[0098] This embodiment provides a method for preparing the above-mentioned positive electrode sheet and an all-solid-state battery containing it, which includes the following steps:

[0099] 1. Preparation of positive electrode sheet

[0100] LiNi 0.8 Mn 0.1 Co 0.1 O2 positive electrode active material, Super P, and PVDF were dry-mixed at 1200 rpm for 15 min. After drying, sieving, and compaction, the mixture was cut into positive electrode active material layers with dimensions of 5 cm × 6 cm using a cutting die. The positive electrode active material layer comprises the following components: 95 wt% LiNi 0.8 Mn 0.1 Co 0.1 The cathode active material consists of O2, 3 wt% conductive carbon black (Super P), and 2 wt% polyvinylidene fluoride (PVDF); the thickness of the cathode active material layer is 180 μm. Simultaneously, an aluminum foil current collector with a size of 5.2 cm × 6.2 cm, a thickness of 12 μm, and a compressive strength of 110 MPa is prepared.

[0101] A 100μm thick TPU buffer layer was stacked on a 115μm thick dense, non-porous PET buffer frame. The length of the TPU buffer layer in the first direction was 10mm, and the length of the positive electrode tab in the first direction was 5.2mm, with a ratio of 25:13. The composite material was then cured and bonded using UV-curable adhesive. A cutting die was used to cut the composite material into rectangular buffer assemblies with an inner frame size of 5cm × 6cm and an outer frame size of 6cm × 7cm.

[0102] The positive electrode active material layer, aluminum foil current collector, and rectangular buffer assembly are hot-pressed and stacked to ensure that the inner wall of the rectangular buffer frame is in close contact with the edge of the positive electrode active material layer. The TPU buffer layer is placed on the side close to the aluminum foil current collector and directly contacts the positive electrode tab. After completion, the above composite structure is placed between two PTFE release sheets and hot-pressed on a flat plate at 80°C and 2MPa for 20 minutes. After cooling to room temperature, the two PTFE release sheets are peeled off to obtain the positive electrode sheet.

[0103] 2. Preparation of negative electrode sheet

[0104] The negative electrode sheet includes a copper foil current collector and a negative electrode active material layer disposed on one side of the copper foil current collector. Based on the total mass of the negative electrode active material layer (100%), the negative electrode active material layer comprises the following components: 93 wt% negative electrode active material, 0.2 wt% conductive carbon black (Super P), 1 wt% single-walled carbon nanotubes (SWCNTs), 4.5 wt% polyacrylic acid (PAA), and 1.3 wt% carboxymethyl cellulose (CMC). The negative electrode active material is composed of 50% silicon dioxide (SiO₂) by mass. x It consists of 50% graphite and 50% graphite.

[0105] This embodiment also provides a method for preparing the above-mentioned negative electrode sheet, which includes the following steps:

[0106] The above-mentioned amounts of negative electrode active material, Super P, SWCNT, PPA and CMC are mixed to prepare a negative electrode active material layer slurry. Then, the negative electrode active material layer slurry is coated onto the surface of the copper foil current collector using a coating machine, thereby forming a negative electrode active material layer on the surface of the copper foil current collector. After baking and rolling, a negative electrode sheet is obtained, which is then cut into a negative electrode sheet with a size of 5.5cm × 6.5cm using a cutting die.

[0107] 3. Preparation of solid electrolyte membranes

[0108] The Li6PS5Cl solid electrolyte membrane was cut into 6cm×7cm pieces using a cutting die.

[0109] 4. Fabrication of all-solid-state batteries

[0110] The positive electrode, Li6PS5Cl solid electrolyte membrane, and negative electrode are stacked concentrically in sequence, with the Li6PS5Cl solid electrolyte membrane placed between the positive and negative electrode. After tab welding, the electrode is placed in an aluminum-plastic film, vacuumed, and then heat-sealed to obtain the battery cell.

[0111] After encapsulation, the cells are subjected to isostatic pressing at 80°C and 500MPa for 5 minutes to obtain a solid-state battery. Before reaching the compressive strength of 100MPa for the aluminum foil current collector, the deformation thickness of the TPU buffer layer is greater than half the thickness of the positive electrode tab, thus providing space to accommodate the positive electrode tab.

[0112] Example 2

[0113] The difference between this embodiment and Embodiment 1 is that the material of the buffer layer in the buffer assembly is replaced with polyolefin elastomer (POE), which has a melting point of 60°C, a tensile strength of 20 MPa, and an elastic modulus of 15 MPa. All other aspects are the same as in Embodiment 1.

[0114] Example 3

[0115] The difference between this embodiment and Embodiment 1 is that the material of the buffer layer in the buffer assembly is replaced with a polyethylene film (PE film) with a melting point of 120°C, a tensile strength of 30 MPa, and an elastic modulus of 300 MPa. All other aspects are the same as in Embodiment 1.

[0116] Example 4

[0117] The difference between this embodiment and Embodiment 1 is that the material of the buffer layer in the buffer assembly is replaced with polyurethane elastomer (PU), which has a melting point of 120°C, a tensile strength of 35 MPa, and an elastic modulus of 400 MPa. All other aspects are the same as in Embodiment 1.

[0118] Example 5

[0119] The difference between this embodiment and Embodiment 1 is that the buffer assembly includes a polyethylene terephthalate (PET) buffer frame, a first buffer layer located on one side of the PET buffer frame, and a second buffer layer located on the other side of the PET buffer frame. The material, thickness, and preparation method of the second buffer layer are the same as those of the first buffer layer, and everything else is the same as in Embodiment 1.

[0120] Example 6

[0121] The difference between this embodiment and Embodiment 1 is that the material of the buffer frame in the buffer assembly is replaced with polycarbonate (PC), with a tensile strength of 170 MPa and an elastic modulus of 2300 MPa. All other aspects are the same as in Embodiment 1.

[0122] Example 7

[0123] The difference between this embodiment and Embodiment 1 is that the length of the TPU buffer layer in the first direction is 3mm, and the length of the positive electrode tab in the first direction is 2mm, that is, the ratio is 3:2.

[0124] Example 8

[0125] The difference between this embodiment and Embodiment 1 is that the length of the TPU buffer layer in the first direction is 50mm, and the length of the positive electrode tab in the first direction is 10mm, that is, the ratio is 5:1.

[0126] Comparative Example 1

[0127] The difference between this comparative example and Example 1 is that the buffer assembly only includes a PET buffer frame and does not have a TPU buffer layer; otherwise, it is the same as Example 1.

[0128] Comparative Example 2

[0129] The difference between this comparative example and Example 1 is that the buffer assembly only includes a TPU buffer layer and does not have a PET buffer border; otherwise, it is the same as Example 1.

[0130] Comparative Example 3

[0131] The difference between this comparative example and Example 1 is that the length of the TPU buffer layer in the first direction is 10mm, and the length of the positive electrode tab in the first direction is 15mm, that is, the ratio is 2:3.

[0132] The all-solid-state batteries provided in Examples 1-8 and Comparative Examples 1-3 were subjected to product yield and performance tests under the following conditions:

[0133] Product qualification rate: The all-solid-state batteries under test were tested using a battery tester. 120 batteries were tested and the product qualification rate was calculated.

[0134] The test results are shown in Table 1:

[0135] Table 1

[0136]

[0137]

[0138] As can be seen from Table 1, in embodiments 1 to 8 of this utility model, by introducing a buffer component with a specific structure into the positive electrode sheet, it can provide additional support, ensuring that the positive electrode sheet and the positive electrode tab can still maintain a good shape at high temperature, thereby avoiding abnormalities such as short circuits between positive and negative electrodes and electrode tab breakage caused by the collapse and deformation of the electrode assembly edge due to isostatic pressure, and improving the product qualification rate of the electrode assembly.

[0139] Comparing Example 1 and Comparative Examples 1 to 2, it can be seen that setting only a single buffer component cannot significantly improve the product manufacturing yield.

[0140] Comparing Example 1 and Comparative Example 3, it can be seen that the present invention improves the product qualification rate by adjusting the ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction.

[0141] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, wherein the positive current collector is provided with a positive electrode tab, characterized in that: The positive electrode includes a buffer assembly, which includes a buffer frame and a buffer layer located on at least one side of the buffer frame; The buffer component is disposed on at least one side of the positive electrode current collector, and the buffer component is circumferentially disposed at the edge of the positive electrode active material layer; The buffer layer is disposed at the contact position between the buffer frame and the positive electrode tab, and the buffer layer is in contact with the positive electrode tab. The ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction is 52:(1~50).

2. The positive electrode sheet according to claim 1, characterized in that, The ratio of the length of the buffer layer in the first direction to the length of the positive electrode tab in the first direction is 52:(25~50).

3. The positive electrode sheet according to claim 1, characterized in that, The thickness of the buffer frame satisfies the following relationship: 5μm≤D1≤(D2-9)μm, where D1 is the thickness of the buffer frame in μm and D2 is the thickness of the positive electrode active material layer in μm.

4. The positive electrode sheet according to claim 1, characterized in that, The buffer layer is an elastic buffer layer.

5. The positive electrode sheet according to claim 1, characterized in that, The thickness of the buffer layer is 10μm to 150μm.

6. The positive electrode sheet according to claim 5, characterized in that, The thickness of the buffer layer is 20μm to 130μm.

7. The positive electrode sheet according to claim 1, characterized in that, The deformation thickness of the buffer component is greater than half the thickness of the positive electrode tab.

8. The positive electrode sheet according to claim 7, characterized in that, The deformation thickness of the buffer component is 5μm to 20μm.

9. The positive electrode sheet according to claim 1, characterized in that, The total thickness of the buffer component after compression is less than or equal to the thickness of the positive electrode active material layer.

10. An all-solid-state battery, characterized in that, The all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane, wherein the positive electrode includes the positive electrode as described in any one of claims 1-9.

Images