Positive electrode sheet and preparation method thereof, all-solid-state battery, battery assembly, and electrical equipment

Abstract

The present application provides a positive electrode sheet and a preparation method thereof, an all-solid-state battery, a battery assembly, and an electrical device. The positive electrode sheet includes a positive electrode active material, a first solid electrolyte, and a second solid electrolyte; the particle size ratio of the positive electrode active material, the first solid electrolyte, and the second solid electrolyte is (3-8):1:(0.1-4). The positive electrode sheet can improve the cycling performance of an all-solid-state battery.

Description

Technical Field

[0001] The present application relates to the field of solid-state battery technology, and in particular to a positive electrode sheet and a preparation method thereof, an all-solid-state battery, a battery assembly, and an electrical device. Background Art

[0002] As a next-generation energy storage technology, all-solid-state batteries are considered a key development direction in the power battery and high-end consumer electronics sectors. Compared to traditional lithium-ion batteries that use liquid electrolytes, all-solid-state batteries utilize non-flammable solid electrolyte materials, fundamentally eliminating the risk of thermal runaway. They also offer a wider operating temperature range and a longer theoretical lifespan.

[0003] In related technologies, all-solid-state batteries typically adopt a laminated structure, consisting of a positive electrode sheet, a solid electrolyte membrane, and a negative electrode sheet stacked in sequence. The positive electrode sheet adopts a composite structure design, comprising two functional layers: a positive electrode active material layer and a solid electrolyte layer. The positive electrode active material layer is mainly composed of lithium transition metal oxides or polyanionic compounds; the solid electrolyte layer is usually a sulfide solid electrolyte or an oxide solid electrolyte, which is combined with the active material layer through dry pressing or solvent-assisted processes to form a complete positive electrode sheet.

[0004] The inventors have found that the cycle performance of the all-solid-state battery prepared using the positive electrode sheet of the above structure is poor. Summary of the Invention

[0005] The embodiments of the present application provide a positive electrode sheet and a preparation method thereof, an all-solid-state battery, a battery assembly, and an electrical device to achieve the effect of improving the cycle performance of the all-solid-state battery.

[0006] In a first aspect, an embodiment of the present application provides a positive electrode sheet, comprising a positive electrode active material, a first solid electrolyte, and a second solid electrolyte;

[0007] The particle size ratio of the positive electrode active material, the first solid electrolyte and the second solid electrolyte is (3-8):1:(0.1-4).

[0008] In one possible embodiment, the particle size of the positive electrode active material is 2.5-18 μm.

[0009] In a possible implementation, the particle size of the first solid electrolyte is 0.1-7 μm; the particle size of the second solid electrolyte is 0.1-12 μm.

[0010] In one possible implementation, the first solid electrolyte is a halide solid electrolyte, and the second solid electrolyte is a sulfide solid electrolyte.

[0011] In a second aspect, an embodiment of the present application provides a method for preparing a positive electrode sheet, comprising:

[0012] Mixing a first solid electrolyte with a positive electrode active material to obtain a first mixed material;

[0013] Mixing the first mixed material with the second solid electrolyte to obtain a positive electrode slurry;

[0014] The positive electrode sheet is obtained by coating with a positive electrode slurry.

[0015] In one possible embodiment, the first mixed material is mixed with the second solid electrolyte to obtain a positive electrode slurry, comprising:

[0016] mixing the first mixed material with a second solid electrolyte and a conductive agent to obtain a second mixed material;

[0017] The second mixed material is mixed with a solvent containing a binder to obtain a positive electrode slurry.

[0018] In a third aspect, an embodiment of the present application provides an all-solid-state battery, comprising a positive electrode sheet, a negative electrode sheet, and a composite electrolyte membrane located between the positive electrode sheet and the negative electrode sheet in any embodiment of the first aspect;

[0019] The composite electrolyte membrane includes a halide solid electrolyte layer and a sulfide solid electrolyte layer;

[0020] The halide solid electrolyte layer is located on the side close to the positive electrode sheet, and the sulfide solid electrolyte layer is located on the side close to the negative electrode sheet.

[0021] In one possible embodiment, the negative electrode sheet includes a negative electrode active material and a sulfide solid electrolyte.

[0022] In a fourth aspect, an embodiment of the present application provides a battery assembly comprising one or more all-solid-state batteries according to any embodiment of the first aspect.

[0023] In the fifth aspect, an embodiment of the present application provides an electrical device, comprising the all-solid-state battery in any embodiment of the third aspect or the battery assembly in any embodiment of the fourth aspect.

[0024] The present invention provides a positive electrode sheet and its preparation method, an all-solid-state battery, a battery assembly, and an electrical device. In this positive electrode sheet, the particle size ratio of the positive electrode active material, the first solid electrolyte, and the second solid electrolyte is designed to be (3-8):1:(0.1-4). The positive electrode active material forms the main skeleton, and the first solid electrolyte and the second solid electrolyte encapsulate the positive electrode active material, forming a three-level particle size gradient filling structure. This multi-level filling effect improves the electrode density, increases the contact area between the positive electrode active material and the solid electrolyte, and constructs a continuous ion transmission channel, which is beneficial for reducing interfacial impedance. The synergistic filling of solid electrolytes of different particle sizes effectively suppresses interfacial separation caused by volume changes of the positive electrode active material during cycling, thereby maintaining the integrity of the positive electrode structure. In addition, this specific particle size ratio can ensure uniform distribution of the components, reduce local current concentration, and effectively alleviate the occurrence of interfacial side reactions. Through this synergistic particle size regulation, the structural degradation of the positive electrode sheet during the cycling of the all-solid-state battery is significantly suppressed, thereby improving the cycling stability of the all-solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] Figure 1 A schematic structural diagram of a positive electrode sheet provided in this application;

[0027] Figure 2 A schematic structural diagram of an all-solid-state battery provided in this application.

[0028] Reference numerals:

[0029] 10. Positive electrode sheet; 11. Positive electrode active material; 12. First solid electrolyte; 13. Second solid electrolyte;

[0030] 20. Composite electrolyte membrane; 21. Halide solid electrolyte layer; 22. Sulfide solid electrolyte layer;

[0031] 30. Negative electrode.

[0032] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0033] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0034] New energy batteries are core components of vehicles like electric vehicles. The rapid development of the new energy electric vehicle market has driven a rapid increase in demand for power batteries. Furthermore, power batteries are also suitable for electric bicycles, electric scooters, manned drones, ships, and other applications. At the same time, people are placing higher demands on the range and safety of new energy electric vehicles. This requires power batteries to achieve both high energy density and high safety. All-solid-state batteries, due to their excellent kinetic performance and thermodynamic stability, can meet these requirements, making them a key research focus both domestically and internationally.

[0035] Compared to liquid lithium-ion batteries, solid-state batteries have considerable application potential in power, consumer, and emerging sectors. All-solid-state batteries use solid electrodes and solid electrolytes, which can significantly increase energy density. Solid-state electrolytes have a wide electrochemical window and are compatible with higher-energy-density positive and negative electrode materials. They can adopt laminated and bipolar plate structures to further increase energy density. At the same time, solid-state electrolytes offer excellent thermal stability, reducing the risk of thermal runaway. Because their overall chemical stability is superior to that of electrolytes and all-solid-state systems, they can slow the formation of lithium dendrites and avoid the risk of short circuits caused by puncturing the battery separator.

[0036] At present, the positive electrode sheet of all-solid-state batteries usually adopts a composite structure design, which includes two functional layers: the positive electrode active material layer and the solid electrolyte layer. The positive electrode active material layer is mainly composed of lithium transition metal oxides or polyanion compounds; the solid electrolyte layer usually uses sulfide solid electrolytes or oxide solid electrolytes, which are combined with the active material layer through dry pressing or solvent-assisted process to form a complete positive electrode sheet.

[0037] When using the aforementioned cathode sheets to prepare all-solid-state batteries, the cathode active material undergoes volume changes during the battery's charge and discharge process. However, the rigid solid electrolyte layer cannot adaptively fill the gaps created by this volume change like a liquid electrolyte, leading to microcracks and contact loss at the interface after cycling. Furthermore, in cathode sheets prepared using dry pressing or solvent-assisted processes, poor solid-solid interface contact between the cathode active material and the solid electrolyte, as well as volume expansion of the electrode material, can lead to decreased battery cycling performance and a reduced cycle life. This is particularly true under high voltage conditions, significantly limiting the cycle life of all-solid-state batteries.

[0038] Based on the above problems, the present application provides a positive electrode sheet and its preparation method, an all-solid-state battery, a battery assembly, and an electrical device. In order to solve the key problem of solid-solid interface contact that restricts the cycle performance of all-solid-state batteries, a multi-level particle size gradient design is adopted to construct a multi-level interface structure system with adaptive characteristics. This particle size ratio enables the positive electrode material to spontaneously maintain close contact during the cycle: the positive electrode active material provides stable support, and the two solid electrolytes maintain ion channels and dynamically compensate for the gaps caused by volume changes. Compared with traditional randomly mixed electrode materials, the positive electrode sheet of the present application can significantly improve the interface contact state by regulating the particle size of the positive electrode material, thereby effectively improving the cycle performance of the all-solid-state battery.

[0039] The following specific embodiments describe in detail the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0040] Figure 1 The schematic diagram of the structure of the positive electrode sheet provided in this embodiment is as follows: Figure 1 As shown, the positive electrode sheet 10 includes a positive electrode active material 11 , a first solid electrolyte 12 and a second solid electrolyte 13 .

[0041] I understand. Figure 1 It is only a schematic diagram and does not represent the actual distribution of the components in the positive electrode sheet 10.

[0042] In this embodiment, the particle size ratio of the positive electrode active material 11 , the first solid electrolyte 12 , and the second solid electrolyte 13 is (3-8):1:(0.1-4).

[0043] For example, the particle size ratios of the positive electrode active material 11 , the first solid electrolyte 12 , and the second solid electrolyte 13 are (6:1:2), (3:1:0.5), (3:1:0.2), (4:1:2), (5:1:3), (6:1:4), and the like.

[0044] Optionally, the particle size of the positive electrode active material 11 is 2.5-18 μm.

[0045] For example, the particle size of the positive electrode active material 11 may be 2.5 μm, 3 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, or 18 μm.

[0046] Optionally, the particle size of the first solid electrolyte 12 is 0.1-7 μm.

[0047] For example, the particle size of the first solid electrolyte 12 may be 0.1 μm, 0.3 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, or 7 μm.

[0048] The particle size of the second solid electrolyte 13 is 0.1-12 μm.

[0049] For example, the particle size of the second solid electrolyte 13 may be 0.1 μm, 0.3 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, or 12 μm.

[0050] In this embodiment, two solid electrolytes of different particle sizes are selected and mixed with a positive electrode active material 11 of larger particle size to prepare a positive electrode sheet 10, which can construct a stable electrode structure with multi-level filling. This hierarchical filling structure shows significant advantages in the cycling process. On the one hand, the synergistic effect of solid electrolytes of different particle sizes ensures that there is always sufficient contact area between the positive electrode active material 11 and the solid electrolyte, effectively reducing the interface impedance; on the other hand, the fluidity of the small-particle solid electrolyte can dynamically compensate for the micro-gaps caused by the volume change of the positive electrode active material 11 during the charge and discharge process, avoiding the common post-cycle contact failure problem in traditional electrodes. The all-solid-state battery assembled with positive electrode sheets 10 designed with different particle size ratios has an increased cycle capacity retention rate, a reduced interface impedance growth rate, and a prolonged battery life.

[0051] By designing the particle size ratio of the positive electrode active material 11, the first solid electrolyte 12 and the second solid electrolyte 13 to be (3-8):1:(0.1-4), such a gradation can make the gaps of the coarse particles just filled by the medium particles, and the gaps of the medium particles just filled by the fine particles, effectively reducing the void ratio, the packing density reaches the maximum value, and shortening the Li + migration path, which improves the + The migration rate of the positive electrode sheet 10 is increased, thereby improving the ionic conductivity of the positive electrode sheet 10. At the same time, when preparing the positive electrode sheet 10, not only the conductive agent is saved and the side reaction between the conductive agent and the solid electrolyte is reduced, but also the electrical performance of the all-solid-state battery is improved.

[0052] Optionally, the first solid electrolyte 12 is a halide solid electrolyte, and the second solid electrolyte 13 is a sulfide solid electrolyte.

[0053] As can be understood, halide solid electrolytes have excellent interfacial chemical stability (especially with oxide positive electrode materials). Their small particle size enables them to form a coating on the surface of the positive electrode active material 11, effectively suppressing interfacial side reactions. Meanwhile, sulfide solid electrolytes, with their high intrinsic ionic conductivity, construct a bulk ion transport network. This combination allows the small-particle halide solid electrolyte to preferentially fill surface defect sites on the positive electrode active material 11, forming a chemically stable, passivating interface. The medium-particle sulfide solid electrolyte maintains overall ionic conductivity, and its larger particle size avoids chemical incompatibility issues caused by direct contact with the positive electrode active material 11. Furthermore, during cycling, the rigid coating of the halide solid electrolyte constrains the volume expansion of the positive electrode active material 11, while the plastic deformation capability of the sulfide solid electrolyte absorbs mechanical stress. Consequently, the charge transport capability of the positive electrode sheet 10 of this embodiment is enhanced, and the all-solid-state battery fabricated therefrom has reduced internal resistance and improved cycling performance.

[0054] Based on the above analysis, this application also provides an all-solid-state battery, such as Figure 2 As shown, the all-solid-state battery of this embodiment includes the positive electrode sheet 10 and the negative electrode sheet 30 in the aforementioned embodiment, and the composite electrolyte membrane 20 located between the positive electrode sheet 10 and the negative electrode sheet 30 .

[0055] At present, the ion transport mechanism of solid-state electrolytes is relatively complex, and the ionic conductivity is lower than that of the electrolyte, which affects the charging and discharging rate. In addition, the ion transport speed may be limited at the interface between the solid-state electrolyte and the electrode material, resulting in poor fast charging performance.

[0056] Sulfide solid electrolytes are considered one of the most promising solid electrolytes due to their high ionic conductivity, good mechanical properties, and ease of synthesis. However, they have a narrow electrochemical window and are easily decomposed at high voltages, increasing the internal resistance of the battery cell and reducing its cycle life.

[0057] Considering the stability of halide solid electrolytes at high voltages, they can be directly contacted with high-voltage transition metal oxide positive electrodes.

[0058] Therefore, the composite electrolyte membrane 20 in the embodiment of the present application includes a halide solid electrolyte layer 21 and a sulfide solid electrolyte layer 22; the halide solid electrolyte layer 21 is located on the side close to the positive electrode sheet 10, and the sulfide solid electrolyte layer 22 is located on the side close to the negative electrode sheet 30.

[0059] The negative electrode sheet 30 in the embodiment of the present application includes a negative electrode active material, a conductive agent, and a binder.

[0060] Since all-solid-state batteries use a sulfide solid electrolyte with high ionic conductivity as the negative electrode side electrolyte layer and a small-particle halide solid electrolyte with high oxidation stability as the electrolyte in the composite positive electrode and the positive electrode side electrolyte layer, the advantages of the two solid electrolytes are combined, giving the all-solid-state battery excellent electrochemical performance.

[0061] Optionally, the negative electrode sheet 30 further includes a sulfide solid electrolyte.

[0062] The present application also provides a method for preparing a positive electrode sheet, comprising the following steps:

[0063] Step 1: Mix the first solid electrolyte 12 and the positive electrode active material 11 to obtain a first mixed material.

[0064] Step 2: Mix the first mixed material with the second solid electrolyte 13 to obtain a positive electrode slurry.

[0065] Specifically, step 2 includes:

[0066] Step 21: Mix the first mixed material with the second solid electrolyte 13 and the conductive agent to obtain a second mixed material.

[0067] Step 22: Mix the second mixed material with a solvent containing a binder to obtain a positive electrode slurry.

[0068] Step 3: coating with positive electrode slurry and drying to obtain a positive electrode sheet 10.

[0069] In the present application, the positive electrode active material 11 is selected from at least one of lithium cobalt oxide, lithium iron phosphate, ternary materials, quaternary materials, lithium-rich manganese-based materials, and lithium manganese iron.

[0070] For example, if the first solid electrolyte 12 is a halide solid electrolyte and the second electrolyte is a sulfide solid electrolyte, the halide solid electrolyte is LiaMXb, where X is selected from one or more of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). a = 1 to 10, and b = 1 to 10. M is a doping element selected from one or more of vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), and nickel (Ni).

[0071] The sulfide solid electrolyte is LaPcSbClcM, wherein a=1-10, b=1-10, c=1-10, and M is a doping element selected from one or more of V, Cr, Mn, Fe, Co, and Ni.

[0072] The conductive agent is selected from at least one of vapor grown carbon fiber (VGCF), superconducting carbon black (sp), carbon (C), and graphite conductive agent (KS-6).

[0073] The binder is selected from at least one of polyvinylidene fluoride-hexafluoropropylene copolymer (BI-F104), polytetrafluoroethylene (BI-PTFE), and polyvinylidene fluoride (PVDF).

[0074] The mass proportion of the positive electrode active material 11 is 60-98%, the mass proportion of the first solid electrolyte 12 and the second solid electrolyte 13 is 1-40%, the mass proportion of the conductive agent is 1-10%, the solid content of the binder is 3-15%, and the solid content of the positive electrode slurry is 50-75%.

[0075] The mass ratio of the first solid electrolyte 12 to the second solid electrolyte 13 may be 1:1, or 2:8, 3:7, etc., which is not limited in the present application.

[0076] Optionally, the mixed material obtained by coating the positive electrode active material 11 with a halide solid electrolyte can be coated not only during the slurry preparation process, but also during the material preparation process, the halide solid electrolyte can be coated on the surface of the positive electrode active material 11 to improve the performance of the mixed material.

[0077] The method for preparing the negative electrode sheet 30 in this application includes the following steps:

[0078] Step 1: Mix the negative electrode active material, conductive agent, binder and solvent to prepare negative electrode slurry.

[0079] Step 2: coating with negative electrode slurry and drying to obtain a negative electrode sheet 30.

[0080] The negative electrode active material accounts for 95-99% by weight, the conductive agent accounts for 0.8-5% by weight, and the binder accounts for 0.6-3% by weight. The solid content of the negative electrode slurry is 50-70%.

[0081] The preparation of the solid electrolyte membrane in the present application includes: preparing the solid electrolyte into an electrolyte slurry; coating the electrolyte slurry on a foil and drying it.

[0082] When assembling the battery, the negative electrode sheet 30 and the solid electrolyte membrane are stacked, and after isostatic pressing, the positive electrode sheet 10 is stacked on the solid electrolyte membrane, and pressed to obtain an all-solid-state battery.

[0083] In the present application, when mixing materials, ball milling, high-speed mixers, blenders, and other equipment can be used for mixing. During ball milling, the speed of the ball mill can be 100-700 rpm / min; the ball milling time can be 30 minutes to 5 hours; and the mass ratio of the material to the ball milling beads in the ball mill can be 1:1-10.

[0084] Before coating the positive and negative electrode slurries, they can be stirred evenly using a high-speed disperser, deaerator, vacuum mixer, etc. During coating, a blade coater, transfer coater, or extrusion coater can be selected as needed. For example, an extrusion coater is suitable for the production of 3C, power, and energy storage batteries.

[0085] The drying temperature of the electrode is 100-150°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0086] The pressure of the isostatic pressing equipment can be 300-1000 MPa; the time can be 3-30 minutes.

[0087] The above preparation method is further described with reference to specific examples.

[0088] 1. Preparation of positive electrode sheet 10:

[0089] Step 1: Place 18.55% Li3InZrCl8 and 70% LiCoO2 (LCO) into a ball mill and mix them. Mill them at a forward and reverse speed of 420 rpm / min for 50 minutes, with a 1-minute break every 15 minutes. The ball milling medium is zirconium beads with a diameter of 1 mm to 20 mm.

[0090] The purpose of this step is to coat Li3InZrCl8 on the surface of LCO particles during the ball milling process.

[0091] Step 2: Add 7.95% Li5PS4Cl2 and 3% VGCF into a ball mill and mix them. Ball mill at a forward and reverse speed of 450 rpm / min for 60 minutes, with a 2-minute break every 15 minutes.

[0092] Step 3: The ball-milled mixed material is mixed with PVDF and ethyl butyrate to prepare a positive electrode slurry with a solid content of 65%.

[0093] Step 4: Use a coating machine to coat the positive electrode slurry on the foil, and place it in a 150° C. oven for drying to obtain the positive electrode sheet 10.

[0094] 2. Preparation of negative electrode sheet 30:

[0095] Step 1: Mix 1.2% VGCF and 98% graphite with PVDF and dibromomethane to prepare a negative electrode slurry with a solid content of 65%.

[0096] Step 2: Use a coating machine to coat the negative electrode slurry on the foil, and place it in a 120° C. oven for drying to obtain the negative electrode sheet 30 .

[0097] The above percentages are all by mass. The differences between Examples 1-4 and Comparative Examples 1-2 and the corresponding battery cycle performance are shown in Table 1.

[0098] Table 1

[0099]

[0100] In comparison examples 1 and 2, the proportion of LCO is adjusted to 88.55%.

[0101] The positive electrode sheets 10 prepared by the preparation methods of Examples 1-4 and Comparative Examples 1-2 were assembled to obtain an all-solid-state battery. After the battery was cycled 100 times, the battery cycle capacity retention rates shown in Table 1 were obtained.

[0102] As shown in Table 1, in Examples 1-4, the composite electrolyte and the positive electrode active material 11 are used for particle size compounding, especially the particle size compounding of Example 2, so that the gaps of the coarse particles are just filled with medium particles, and the gaps of the medium particles are just filled with fine particles, and the porosity reaches the minimum value, which not only makes the ionic conductivity of the positive electrode sheet 10 higher, but also improves the electrical performance of the battery. It can be seen that the use of the halide solid electrolyte-coated positive electrode active material 11 as the positive electrode material in the composite solid electrolyte system can effectively solve the problem of poor interface performance of the all-solid-state battery at high voltage, improve the stability and rate performance of the all-solid-state battery, and the cut-off voltage of the all-solid-state battery can reach 4.3V-4.8V. In addition, the preparation of the above-mentioned all-solid-state battery does not require special material doping or modification, the preparation process is simple, and the preparation cost is low.

[0103] In Comparative Examples 1 and 2, a sulfide solid electrolyte is used alone to mix with the positive electrode active material 11. Since the sulfide solid electrolyte is not resistant to high voltage, it is easy to produce chemical side reactions under high voltage (above 4.3V), which reduces the electrochemical performance of the battery and accelerates battery failure.

[0104] The present application also provides a battery assembly comprising one or more of the all-solid-state batteries of the aforementioned embodiments.

[0105] The present application also provides an electrical device, including the all-solid-state battery in the aforementioned embodiment or the battery assembly in the aforementioned embodiment.

[0106] Specifically, the electrical equipment may include, but is not limited to, electric vehicles, battery vehicles, mobile phones, tablet computers, laptop computers, electric toys, ships, spacecraft, etc. Electric toys may include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric airplane toys, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft.

[0107] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. An all-solid-state battery, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and a composite electrolyte membrane located between the positive electrode sheet and the negative electrode sheet; The positive electrode sheet includes a positive electrode active material, a first solid electrolyte and a second solid electrolyte; the first solid electrolyte is a halide solid electrolyte; the second solid electrolyte is a sulfide solid electrolyte; The particle size ratio of the positive electrode active material, the first solid electrolyte and the second solid electrolyte is (3-8):1:(0.1-4), and the composite electrolyte membrane includes a halide solid electrolyte layer and a sulfide solid electrolyte layer; The halide solid electrolyte layer is located on a side close to the positive electrode sheet, and the sulfide solid electrolyte layer is located on a side close to the negative electrode sheet.

2. The all-solid-state battery according to claim 1, characterized in that The particle size of the positive electrode active material is 2.5-18 μm.

3. The all-solid-state battery according to claim 1, characterized in that The particle size of the first solid electrolyte is 0.1-7 μm; The particle size of the second solid electrolyte is 0.1-12 μm.

4. The all-solid-state battery according to claim 1, characterized in that The negative electrode sheet includes a negative electrode active material and a sulfide solid electrolyte.

5. A method for preparing a positive electrode sheet, characterized in that: include: Mixing a first solid electrolyte with a positive electrode active material to obtain a first mixed material; Mixing the first mixed material with the second solid electrolyte to obtain a positive electrode slurry; The positive electrode sheet is obtained by coating the positive electrode slurry; the positive electrode sheet is the positive electrode sheet in the all-solid-state battery according to any one of claims 1 to 4.

6. The method for preparing a positive electrode sheet according to claim 5, characterized in that: The step of mixing the first mixed material with the second solid electrolyte to obtain a positive electrode slurry comprises: Mixing the first mixed material with a second solid electrolyte and a conductive agent to obtain a second mixed material; The second mixed material is mixed with a solvent containing a binder to obtain the positive electrode slurry.

7. A battery assembly, characterized in that: Comprising one or more all-solid-state batteries according to any one of claims 1 to 4.

8. An electrical device, characterized in that: Includes the all-solid-state battery as described in any one of claims 1 to 4, or includes the battery assembly as described in claim 7.

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