All-solid-state battery, battery pack and electrical device

Abstract

An all-solid-state battery, a battery pack, and an electrical device. The all-solid-state battery comprises negative electrode sheets and a positive electrode sheet which are alternately stacked, solid-state electrolyte layers being provided between the negative electrode sheets and the positive electrode sheet, and the outermost sides of the all-solid-state battery being the negative electrode sheets. The negative electrode sheets each comprises a negative electrode current collector and, respectively arranged on the surfaces of two sides of the negative electrode current collector, a negative electrode active material layer and a ceramic layer, the ceramic layer being located on the surface of the side of the negative electrode current collector facing away from the positive electrode sheet.

Description

All-solid-state battery, battery pack and electric device

[0001] The present disclosure claims priority to the Chinese patent application No. 202411080069.X, filed on August 7, 2024, entitled "All-solid-state battery, battery pack and electric device", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the field of solid-state batteries, and relates to an all-solid-state battery, a battery pack and an electric device. BACKGROUND

[0003] With the promotion of the large-scale application of electric vehicles in the world, lithium-ion batteries have experienced rapid development. The existing liquid lithium-ion batteries are close to the limit of their energy density, and the liquid electrolyte has the risk of being flammable and explosive, resulting in low safety performance of the battery. Compared with liquid batteries, solid-state batteries have higher safety performance and energy density, and in addition, they also have certain advantages in power characteristics and temperature adaptability, which are expected to greatly improve the cruising range and charging performance of electric vehicles.

[0004] In the production process of all-solid-state batteries, the positive electrode sheet, solid-state electrolyte and negative electrode sheet are generally stacked together for assembly. In order to form a good solid-solid contact interface between the solid-state electrolyte and the electrode, and to avoid problems such as contact loss and lithium dendrite formation during the cycle process, high pressure needs to be applied during stacking to make the materials densely packed. The pressure provided by traditional hot pressing and rolling is limited and uneven, which makes it difficult to ensure the consistency of dense packing, thereby adversely affecting the performance of the battery. Isostatic pressing technology is based on Pascal's principle, which places the powder of the part to be pressed in a high-pressure container, and uses the incompressible and uniformly transmitted pressure of liquid or gas medium to uniformly press the workpiece from all directions, so that the powder receives consistent pressure in all directions, thereby realizing the forming of high-density and high-uniformity blanks. Isostatic pressing technology can densify different types of materials such as metals, ceramics, composites and polymers, and eliminate pores. For all-solid-state batteries, isostatic pressing technology can effectively eliminate the voids inside the battery, improve the contact effect between the internal components of the battery, and thereby enhance the electrical conductivity and improve the energy density.

[0005] When the full solid-state battery is isostatic pressing forming, the pressure is generally more than 400Mpa, which is easy to cause the battery to be broken and scrapped. In order to ensure that the battery is uniformly stressed during isostatic pressing and avoid the occurrence of the broken phenomenon, a clamping plate made of stainless steel or aluminum is usually arranged between the battery packaging film and the electrode assembly. However, after the clamping plate is arranged, the clamping plate is easy to pierce the packaging film during isostatic pressing, which causes the battery to be short-circuited and unable to be used. In addition, if the pressure bearing capacity of the full solid-state battery is low, the internal pressure of the battery is also unevenly distributed during the subsequent constrained pressing process, which is not conducive to the initial efficiency and cycle performance of the battery. SUMMARY

[0006] In view of the above defects, the present disclosure provides a full solid-state battery, a battery pack and an electrical equipment. The present disclosure designs the outermost layer of the battery as a ceramic layer, utilizes the good rigidity and hardness of the ceramic layer itself, and enables the battery to bear a large pressure during isostatic pressing, so as to ensure uniform stress and flat pressure surface, and the packaging film is not easy to be broken. In addition, the pressure surface is kept flat during the subsequent constrained pressing process, so that the battery has good initial efficiency and cycle performance.

[0007] The present disclosure provides a full solid-state battery, comprising negative electrode sheets and positive electrode sheets arranged in an interleaved and stacked manner, and a solid-state electrolyte layer between the negative electrode sheets and the positive electrode sheets. The outermost side of the full solid-state battery is the negative electrode sheet. The negative electrode sheet comprises a negative electrode current collector and negative electrode active material layers and ceramic layers arranged on both side surfaces of the negative electrode current collector, respectively. The ceramic layer is located on the side surface of the negative electrode current collector away from the positive electrode sheet.

[0008] The full solid-state battery described above, wherein the ceramic layer satisfies at least one of the following conditions:

[0009] (1) Mohs hardness is 3-10;

[0010] (2) Poisson's ratio is 0.1-0.5;

[0011] (3) Density is 50%-90%;

[0012] (4) Elastic modulus is 2-10GPa.

[0013] The full solid-state battery described above, wherein the thickness of the ceramic layer is 30-150μm.

[0014] The full solid-state battery described above, wherein the ceramic layer comprises ceramic particles and a binder;

[0015] Based on the total mass of the ceramic layer, the mass content of the ceramic particles is 40%-80%, and the mass content of the binder is 1%-10%.

[0016] The all-solid-state battery as described above, wherein the ceramic particles include one or more of alumina, zirconia, boehmite, lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate, titanium dioxide, silicon carbide, silicon oxide, and silicon nitride.

[0017] The all-solid-state battery as described above, wherein the ceramic particles have a particle size D50 of 0.1-3 μm.

[0018] The all-solid-state battery as described above, wherein the ceramic layer is prepared by a method including the following steps:

[0019] The ceramic particles and the binder are mixed in a solvent to obtain a ceramic slurry, the ceramic slurry is coated on one side surface of the negative electrode current collector, and the ceramic layer is obtained after heat treatment and roll pressing in sequence.

[0020] The all-solid-state battery as described above, wherein the heat treatment includes first heat treatment and second heat treatment in sequence.

[0021] The first heat treatment has a temperature of 60-200°C, and the second heat treatment has a temperature of 300-800°C.

[0022] The all-solid-state battery as described above, wherein the roll pressing has a pressure of 5-50 MPa.

[0023] The disclosure also provides a battery pack including the all-solid-state battery as described above.

[0024] The disclosure also provides an electrical equipment including the all-solid-state battery as described above or the battery pack as described above.

[0025] The disclosure has at least the following beneficial effects:

[0026] The disclosure has at least the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a schematic view of the structure of an all-solid-state battery according to an embodiment of the disclosure.

[0028] Reference signs: 1-negative electrode sheet; 11-negative electrode current collector; 12-ceramic layer; 13-negative electrode active material layer; 2-positive electrode sheet; 21-positive electrode current collector; 22-positive electrode active material layer; 3-solid electrolyte layer. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

[0030] The present disclosure provides a kind of all-solid-state battery, including staggered layer arrangement negative pole piece and positive pole piece, including solid electrolyte layer between negative pole piece and positive pole piece, the outermost side of all-solid-state battery is negative pole piece, wherein, negative pole piece includes negative pole current collector and the negative pole active material layer and ceramic layer respectively arranged in the two side surfaces of negative pole current collector, wherein, ceramic layer is located in the side surface of negative pole current collector away from positive pole piece.

[0031] In the present disclosure, the negative pole piece and the positive pole piece staggered layer arrangement refers to the state of the positive and negative of all-solid-state battery, and a solid electrolyte layer is arranged between each pair of adjacent positive and negative pole pieces. The present disclosure does not limit the number of positive pole pieces and negative pole pieces. The number of positive pole pieces is at least one, and the number of negative pole pieces is at least two. The specific number of positive and negative pole pieces can be determined according to the design capacity of the battery. Compared with arranging the positive pole piece on the outermost side of the battery, arranging the negative pole piece on the outermost side of the battery can ensure that the lithium ions released from the positive pole active material layer can be received by the negative pole active material layer, thereby avoiding unnecessary loss of battery energy density. When the number of negative pole pieces exceeds two, the all-solid-state battery includes a negative pole piece located inside the battery and a negative pole piece located on the outermost side of the battery. The two side surfaces of the negative pole piece located inside the battery are provided with negative pole active material layers. The two side surfaces of the negative pole piece located on the outermost side of the battery are respectively provided with a negative pole active material layer and a ceramic layer. The ceramic layer is located on the side surface of the negative pole current collector away from the positive pole piece.

[0032] FIG. 1 is a schematic diagram of the structure of an all-solid-state battery according to an embodiment of the present disclosure. In the example shown in FIG. 1, the all-solid-state battery includes two negative pole pieces 1 located on the outermost side of the battery and one positive pole piece 2 arranged between the two negative pole pieces 1. The all-solid-state battery also includes a solid electrolyte layer 3 between the negative pole pieces 1 and the positive pole piece 2. The outermost negative pole piece 1 includes a negative pole current collector 11 and a ceramic layer 12 and a negative pole active material layer 13 arranged on the two side surfaces of the negative pole current collector 11, respectively. The positive pole piece 2 includes a positive pole current collector 21 and a positive pole active material layer 22 arranged on the two side surfaces of the positive pole current collector 21. The ceramic layer 12 is arranged on the side surface of the negative pole current collector 11 away from the positive pole piece 2, and the negative pole active material layer 13 is arranged on the side surface of the negative pole current collector 11 facing the positive pole piece 2, so as to receive the active lithium released from the positive pole active material layer 22.

[0033] The present disclosure designs the outermost layer of the all-solid-state battery as a ceramic layer through special design of the structure of the all-solid-state battery, and utilizes the high rigidity and hardness of the ceramic layer itself to ensure uniform stress when a large pressure is borne in the isostatic pressing process, so that the pressure surface is flat and the outer packaging film is not easily broken, and the surface remains flat in the subsequent constrained pressing process, so that the all-solid-state battery has good initial efficiency and cycle performance.

[0034] In addition, after the isostatic pressing process is completed, the conventional splint needs to be taken out and re-packaged, and the process is relatively complex, while the outermost ceramic layer of the present disclosure is designed integrally with the battery, which not only makes the pressure more uniform, but also does not need to be taken out and re-packaged after the isostatic pressing process is completed, simplifying the manufacturing process. When the battery is impacted by external force or pierced by foreign matter, the outermost ceramic layer can also play a barrier role to avoid short circuit of the battery and enhance the safety performance of the battery.

[0035] In a preferred embodiment, the ceramic layer satisfies at least one of the following conditions:

[0036] (1) Mohs hardness is 3-10;

[0037] (2) Poisson's ratio is 0.1-0.5;

[0038] (3) Density is 50%-90%;

[0039] (4) Elastic modulus is 2-10 GPa.

[0040] The Mohs hardness, Poisson's ratio, density and elastic modulus of the ceramic layer are key factors affecting the isostatic pressing effect of the battery.

[0041] The Mohs hardness is a parameter for characterizing the hardness of a material, which is usually measured by scratching the surface of the tested material with a pyramidal diamond needle, and measuring the depth of the scratch. The depth of the scratch is the Mohs hardness. The Mohs hardness is generally divided into 1-10 levels, and the larger the value, the greater the hardness of the material. When the Mohs hardness of the ceramic layer is 5-8, it is beneficial to maintain good flatness when bearing the pressure of isostatic pressing, and the battery is not easily deformed.

[0042] Poisson's ratio refers to the ratio of the absolute value of the transverse normal strain to the axial normal strain when the material is subjected to uniaxial compression or tension, and is an elastic parameter reflecting the transverse deformation of the material. Its value range is between -1 and 0.5, and a positive number indicates that the material will shrink in the transverse direction under stress, and a negative number indicates that it will expand. Among them, 0.5 is the maximum theoretical value, representing that the material will not change in volume when subjected to uniaxial compression or tension. By controlling the Poisson's ratio of the ceramic layer to be within 0.1-0.3, the present disclosure can ensure that the ceramic layer has high rigidity and is not easily deformed during the isostatic pressing process.

[0043] The density of the ceramic layer refers to the ratio of the actual density of the ceramic layer to the theoretical density, wherein the actual density can be obtained by an electronic density instrument prepared based on the principle of Archimedes drainage method. By controlling the density of the ceramic layer to be in the range of 60% to 90%, the hardness and mechanical properties of the ceramic layer can be improved.

[0044] The elastic modulus refers to the ratio of the axial stress to the axial strain of the material in the elastic deformation stage, also known as Young's modulus. The elastic modulus can be regarded as an index for measuring the difficulty of elastic deformation of the material. The greater the value, the greater the stress required to cause a certain elastic deformation of the material, i.e., the greater the rigidity of the material, and the smaller the elastic deformation under a certain stress. By controlling the elastic modulus of the ceramic layer to be in the range of 3 to 8 GPa, the ceramic layer can also have greater rigidity and is not easily deformed during isostatic pressing.

[0045] In a specific embodiment, the thickness of the ceramic layer is 30 to 150 μm, preferably 50 to 100 μm. It can be understood that the greater the thickness of the ceramic layer, the more advantageous it is to resist the adverse strain that is likely to occur during isostatic pressing of the all-solid-state battery. However, an excessively large thickness will inevitably result in a compromised energy density of the all-solid-state battery. Therefore, controlling the ceramic layer to be in the above thickness range can enable it to play a protective role while also enabling the all-solid-state battery to have excellent energy density. Exemplarily, the thickness of the ceramic layer can be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc.

[0046] In a specific embodiment, the ceramic layer comprises ceramic particles and a binder; the mass content of the ceramic particles is 40% to 80%, and the mass content of the binder is 1% to 10%, based on the total mass of the ceramic layer. By having the ceramic layer comprise ceramic particles and a binder in the above mass content ranges, the ceramic layer can maintain high rigidity and hardness while also having good adhesion to the surface of the negative electrode current collector.

[0047] The type of ceramic particles is not specifically limited in the present disclosure, and can be selected from ceramic materials commonly used in the art, including but not limited to one or more of alumina, zirconia, boehmite, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium aluminum titanium phosphate (LATP), titanium dioxide, silicon carbide, silicon oxide, and silicon nitride.

[0048] If the particle size of the ceramic particles is too small, the ceramic particles are prone to agglomeration during the slurry preparation process. If the particle size of the ceramic particles is too large, it is difficult to form a dense packing in the ceramic layer, which is not conducive to withstand a large isostatic pressure. In view of the above, the particle size D50 of the ceramic particles is controlled to be 0.1-3 μm. For example, it can be 0.1 μm, 0.3 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, etc.

[0049] The kind of the binder is not particularly limited in the present disclosure, and it can be selected from the binders commonly used in the art, such as acrylate binders.

[0050] In a specific embodiment, the ceramic layer can be prepared by a method comprising the following processes:

[0051] The ceramic particles and the binder are mixed in a solvent to obtain a ceramic slurry. The ceramic slurry is coated on one side surface of the negative electrode current collector, and then subjected to heat treatment and roll pressing to obtain the ceramic layer.

[0052] In order to enable the ceramic particles and the binder to be fully dispersed in the solvent, a dispersant can be added during the preparation of the slurry.

[0053] Specifically, the dispersant can be selected from one or more of silicate dispersants, alkali metal phosphate dispersants, and organic dispersants. The organic dispersant includes but is not limited to one or more of triethylhexyl phosphoric acid, sodium dodecyl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, gum gur, and fatty acid polyethylene glycol esters.

[0054] Further, the mass ratio of the ceramic particles to the dispersant is 10:(0.1-3). The mass ratio can be selected within the above range according to the dispersing capacity of the dispersant and the type of the ceramic particles.

[0055] For example, the mass ratio of the ceramic particles to the dispersant can be 10:0.1, 10:0.5, 10:1, 10:1.5, 10:2, 10:2.5, 10:3, or a range formed by any two of the above values.

[0056] The solvent used for dispersing the ceramic particles and the binder is not particularly limited in the present disclosure, and it can include but is not limited to one or more of water, N-methyl pyrrolidone (NMP), dimethylbenzene, anisole, butyl butyrate, isobutyl isobutyrate, N,N-dimethylformamide (DMF), acetonitrile, etc.

[0057] In a specific embodiment, the solid content of the prepared ceramic slurry can be controlled to be 30wt% to 90wt%, more preferably 40wt% to 80wt%. The greater the solid content of the ceramic slurry, the greater the viscosity, and the more difficult the coating. Controlling the solid content of the ceramic slurry within the above range is conducive to the coating of the ceramic slurry.

[0058] The heat treatment is a process of drying the ceramic slurry to form a solid ceramic layer. In a preferred embodiment, the heat treatment comprises a first heat treatment and a second heat treatment performed in sequence, wherein the temperature of the first heat treatment is 60 to 200℃, and the temperature of the second heat treatment is 300 to 800℃.

[0059] Illustratively, the temperature of the first heat treatment is 60℃, 80℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, or a range defined by any two of the above values; and the temperature of the second heat treatment is 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, or a range defined by any two of the above values. Performing the first heat treatment at a lower temperature is conducive to the volatilization of the solvent and the drying process of the slurry; and performing the second heat treatment at a higher temperature is conducive to the densification of the ceramic particles and the enhancement of the density of the ceramic layer.

[0060] The ceramic layer can be further densified and its surface can be made more flat through the roll pressing process. In a preferred embodiment, the pressure of the roll pressing process is 5 to 50MPa, more preferably 10 to 40MPa.

[0061] Illustratively, the pressure is 5MPa, 10MPa, 15MPa, 20MPa, 25MPa, 30MPa, 35MPa, MPa, 40MPa, 50MPa, or a range defined by any two of the above values.

[0062] The present disclosure does not make specific limitations on the type of negative current collector, which can be selected from the negative current collectors commonly used in the art, including but not limited to copper foil, carbon-coated copper foil, etc.

[0063] In a specific embodiment, the main component of the negative active material layer is the negative active material, and in addition thereto, the negative active material layer can further include components such as conductive agent, binder, etc.

[0064] Specifically, the negative active material includes, but is not limited to, one or more of graphite, silicon-carbon material, silicon-oxygen material, and elemental silicon; the conductive agent includes, but is not limited to, one or more of conductive carbon black, Super-C, acetylene black, Ketjen black, and carbon nanofiber; and the binder includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC-Na), polyvinylpyrrolidone, polytetrafluoroethylene, styrene butadiene rubber (SBR), and hydrogenated nitrile rubber (HNBR).

[0065] In a specific embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on both sides of the positive electrode current collector. The positive electrode current collector can be selected from the positive electrode current collectors commonly used in the art, such as aluminum foil; and the main component of the positive electrode active material layer is positive electrode active material, in addition to which the positive electrode active material layer can further include conductive agent, binder, and the like. Specifically, the conductive agent and the binder can be selected in accordance with the selection of the conductive agent and the binder in the negative electrode sheet, which will not be described here again. The positive electrode active material can be selected from the positive electrode active materials commonly used in the art, including but not limited to one or more of lithium cobaltate, lithium nickelate, lithium manganate, lithium manganate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium iron phosphate, lithium nickel manganate, and lithium-rich manganese-based material.

[0066] The solid-state electrolyte layer of the present disclosure includes a solid-state electrolyte, and the present disclosure does not particularly limit the type of solid-state electrolyte, which can be, for example, a sulfide electrolyte.

[0067] In a specific embodiment, the all-solid-state battery of the present disclosure can be prepared by the following method:

[0068] 1) Preparation of the positive electrode sheet: dispersing the positive electrode active material, the conductive agent, and the binder in a solvent to form a positive electrode slurry; coating the positive electrode slurry on both sides of the positive electrode current collector, drying, rolling, and slitting to obtain the positive electrode sheet;

[0069] 2) Preparation of the negative electrode sheet: dispersing the negative electrode active material, the conductive agent, and the binder in a solvent to form a negative electrode active material layer slurry, coating the negative electrode active material layer slurry on one side of the negative electrode current collector, dispersing the ceramic particles and the binder in a solvent to form a ceramic slurry, coating the ceramic slurry on the other side of the negative electrode current collector, drying, rolling, and slitting to obtain the negative electrode sheet;

[0070] 3) Preparation of the solid-state electrolyte layer: dispersing the solid-state electrolyte and the binder in a solvent to form a solid-state electrolyte layer slurry, coating the solid-state electrolyte layer slurry on a substrate, and drying to form the solid-state electrolyte layer.

[0071] 4) Transferring the solid-state electrolyte layer from the surface of the substrate to the surface of the negative electrode sheet including the negative electrode active material layer.

[0072] 5) Assembling the battery: the negative electrode sheet and the positive electrode sheet comprising the solid electrolyte layer are alternately stacked, and the solid electrolyte layer is located between the negative electrode sheet and the positive electrode sheet, the negative electrode sheet is located at the outermost side of the battery, and the ceramic layer of the negative electrode sheet faces away from the positive electrode sheet. After encapsulation, isostatic pressing treatment is performed to obtain a full solid-state battery.

[0073] Further, the temperature of the isostatic pressing treatment is 25-150°C, and the pressure is 400-800Mpa.

[0074] Exemplarily, the temperature is 25°C, 55°C, 85°C, 115°C, 150°C, or a range formed by any two of the above values; the pressure is 400Mpa, 450Mpa, 500Mpa, 550Mpa, 600Mpa, 650Mpa, 700Mpa, 750Mpa, 800Mpa, or a range formed by any two of the above values.

[0075] Further, when the full solid-state battery further comprises a negative electrode sheet located between the two positive electrode sheets, the negative electrode sheet is obtained by coating a negative electrode active material layer slurry on both sides of the surface of the negative electrode current collector, and then drying, rolling, and cutting.

[0076] The second aspect of the present disclosure provides a battery pack comprising the full solid-state battery provided by the first aspect of the present disclosure. In addition to the full solid-state battery, the battery pack of the present disclosure can further comprise a shell and the like, and specifically, a plurality of full solid-state batteries can be assembled in the shell to form a battery pack. The number of full solid-state batteries can be selected according to different capacity requirements of the battery pack.

[0077] The battery pack of the present disclosure has excellent initial efficiency and cycle performance due to the inclusion of the above full solid-state battery.

[0078] The third aspect of the present disclosure provides a power consuming device comprising the full solid-state battery provided by the first aspect of the present disclosure or the battery pack provided by the second aspect of the present disclosure. The present disclosure does not particularly limit the type of power consuming device, including but not limited to mobile phones, portable devices, notebook computers, electric bicycles, electric vehicles, electric toys, energy storage devices, and the like.

[0079] The full solid-state battery provided by the present disclosure will be described in detail below in conjunction with specific embodiments.

[0080] Embodiment 1

[0081] The present embodiment provides a full solid-state battery, which has the same battery structure as that of FIG. 1, comprising two negative electrode sheets 1 and one positive electrode sheet 2, wherein the two negative electrode sheets 1 are located at the outermost side of the battery, and the positive electrode sheet 2 is located between the two negative electrode sheets 1, and further comprising a solid electrolyte layer 3 between the negative electrode sheet 1 and the positive electrode sheet 2. The preparation method of the full solid-state battery comprises the following steps:

[0082] 1. Preparation of negative electrode sheet 1

[0083] 1) Ceramic particles alumina with a particle size D50 of 0.2 μm, dispersant methyl pentanol, binder polyacrylic acid were mixed in a mass ratio of 88:7:5, and then dispersed in solvent water to obtain a ceramic slurry with a solid content of 70 wt%, the ceramic slurry was coated on one side surface of the negative current collector 11 copper foil, after first heat treatment at 120℃ for 6h, second heat treatment at 500℃ for 3h, and then roll pressing under a pressure of 30MPa, a ceramic layer 12 with a thickness of 50μm was formed.

[0084] 2) Pure silicon, conductive agent acetylene black, binder CMC were dispersed in solvent water in a mass ratio of 97.5:0.5:2 to obtain a negative active material layer slurry with a solid content of 46%, the negative active material layer slurry was coated on the other side surface of the negative current collector 11 copper foil, and after drying and roll pressing, a negative active material layer 13 was formed, and then a negative electrode sheet 1 was obtained.

[0085] 2. Preparation of positive electrode sheet 2

[0086] The positive active material single crystal ternary lithium nickel cobalt manganese oxide NCM811, conductive agent acetylene black, binder HNBR were dispersed in solvent dimethylbenzene in a mass ratio of 94.5:0.5:5 to obtain a positive active material layer slurry with a solid content of 75%, the positive active material layer slurry was coated on both side surfaces of the positive current collector 21 aluminum foil, and after drying and roll pressing, a positive active material layer 22 was formed, and then a positive electrode sheet 2 was obtained.

[0087] 3. Preparation of solid-state electrolyte layer 3

[0088] The sulfide electrolyte Li6PS5Cl (LPSCl), binder SBR were dispersed in solvent dimethylbenzene in a mass ratio of 99:1 to obtain a solid-state electrolyte layer slurry with a solid content of 60%, the solid-state electrolyte layer slurry was coated on the surface of the aluminum foil substrate, and after drying, a solid-state electrolyte layer 3 was formed, and the solid-state electrolyte layer 3 was transferred from the aluminum foil substrate to the surface of the negative electrode sheet 1 provided with the negative active material layer 13.

[0089] 4. Assembly of the battery

[0090] The negative electrode sheet 1 including the solid-state electrolyte layer 3, the positive electrode sheet 2, and the negative electrode sheet 1 including the solid-state electrolyte layer 3 were sequentially stacked, and the ceramic layer 12 in the negative electrode sheet 1 was located at the outermost side, and the solid-state electrolyte layer 3 was located between the negative electrode sheet 1 and the positive electrode sheet 2 to obtain an electrode assembly, the electrode assembly was packaged in an aluminum plastic film, and isostatic pressing treatment was carried out at 80℃ and 500Mpa to obtain a full solid-state battery.

[0091] Examples 2-13

[0092] The preparation method of the all-solid-state battery of Examples 2 to 13 is basically the same as that of Example 1, and the specific differences are listed in Table 1. Among them, the ceramic layer rolling pressure refers to the pressure of the rolling treatment performed after the second heat treatment is completed.

[0093] Table 1

[0094] In Example 13, “not using” means not including the operation of the second heat treatment.

[0095] Comparative Example 1

[0096] This comparative example provides an all-solid-state battery, which has a battery structure similar to that of FIG. 1, except that the ceramic layer 12 in the negative electrode sheet 1 is replaced by a negative electrode active material layer 13, so that both surfaces of the negative electrode sheet 1 are negative electrode active material layers 13.

[0097] Comparative Example 2

[0098] This comparative example provides an all-solid-state battery, which has a battery structure basically the same as that of Comparative Example 1, except that a 50-μm-thick clip plate made of stainless steel is placed on the surface of the two outermost negative electrode active material layers 13.

[0099] Comparative Example 3

[0100] This comparative example provides an all-solid-state battery, which has a battery structure basically the same as that of Comparative Example 2, except that the position of the clip plate is replaced from the surface of the negative electrode active material layer 13 to the surface of the aluminum plastic film.

[0101] Test Example

[0102] I. Test the following parameters on the ceramic layer of the negative electrode sheet in the above examples:

[0103] 1. Mohs hardness

[0104] Test method: Use a pyramid-shaped diamond needle to scratch the surface of the ceramic layer, and measure the depth of the scratch, which is the Mohs hardness.

[0105] 2. Poisson's ratio

[0106] Test method: Refer to GB / T 22315-2008 for testing.

[0107] 3. Elastic modulus

[0108] Test method: Refer to GB / T 22315-2008 for testing.

[0109] 4. Density

[0110] Test method: Test based on the principle of Archimedes drainage method.

[0111] The test results are shown in Table 2.

[0112] II. The following performances of the all-solid-state batteries of the above examples and comparative examples were tested:

[0113] 1. The state after isostatic pressing

[0114] Test method: The damage of the aluminum-plastic film after isostatic pressing was observed by naked eye, and the flatness of the battery surface was tested, wherein the flatness of the battery surface was judged by testing the included angle between the battery surface and the horizontal plane, the included angle of 0-0.5° indicated that the battery surface was perfect and flat, the included angle of 0.5°-1° indicated that the battery surface was slightly curved, the included angle >1° and <5° indicated that the battery surface was curved, and the included angle ≥5° was obviously curved. When the battery was obviously curved during the isostatic pressing process, the battery would be broken during the subsequent constrained pressure cycle, resulting in short circuit of the battery and unable to cycle.

[0115] 2. The initial efficiency

[0116] Test method: The all-solid-state battery was subjected to isostatic pressing at 10 MPa, and at the same time, the battery was charged to 4.2 V at a current density of 0.4 mA / cm 2 2, and then charged at a constant voltage until the current decreased to 0.02 C. After standing for 5 min, the battery was discharged to 3 V at a constant current of 0.1 C. The initial charge capacity Qcharge and the initial discharge capacity Qdischarge of the all-solid-state battery were recorded, and the initial charge-discharge efficiency η = Edischarge / Echarge x 100% of the all-solid-state battery was calculated.

[0117] 3. Capacity retention rate after 200 cycles

[0118] Test method: The all-solid-state battery was subjected to isostatic pressing at 10 MPa, and at the same time, the battery was charged to 4.2 V at a current density of 0.4 mA / cm 2 2, and then charged at a constant voltage until the current decreased to 0.02 C. After standing for 5 min, the battery was discharged to 3 V at a constant current of 0.1 C. The initial charge capacity Qcharge and the initial discharge capacity Qdischarge of the all-solid-state battery were recorded, and the initial charge-discharge efficiency η = Edischarge / Echarge x 100% of the all-solid-state battery was calculated.

[0119] The test results are shown in Table 3.

[0120] Table 2

[0121] Table 3

[0122] From Table 2, 3, the following conclusions can be drawn:

[0123] 1) By comparing Example 1, 2, 7, 8, when the ceramic particles are selected from alumina, LLZTO, LATP, the ceramic layer has high Mohs hardness, elastic modulus, low Poisson's ratio and high density, and the obtained all-solid-state battery has intact aluminum plastic film after isostatic pressing, smooth battery surface, and high initial efficiency and cycle capacity retention rate. When the ceramic particles are selected from boehmite, the Mohs hardness of the ceramic layer is low, and the Poisson's ratio is relatively high. Although the all-solid-state battery can still maintain the state of intact aluminum plastic film and smooth surface after isostatic pressing, the initial efficiency and cycle capacity retention rate of the all-solid-state battery decrease significantly. The reason is that boehmite is easy to absorb water, which not only affects the hardness of the ceramic layer, but also has an adverse effect on the initial efficiency and cycle performance of the all-solid-state battery.

[0124] 2) By comparing Example 1 and Example 3, when the solid content of the ceramic slurry is 50% and 70%, the ceramic layer has high Mohs hardness, low Poisson's ratio and high density, and the aluminum plastic film is intact after isostatic pressing, the surface of the all-solid-state battery is smooth, and it has excellent initial efficiency and cycle performance.

[0125] 3) By comparing Example 1, 4, 12, the change of the thickness of the ceramic layer has no obvious effect on the Mohs hardness, elastic modulus, Poisson's ratio and density. However, when the thickness of the ceramic layer is small (30 μm), the pressure resistance of the all-solid-state battery becomes weak, the surface of the all-solid-state battery appears slightly curved after isostatic pressing, and the initial efficiency and cycle capacity retention rate of the all-solid-state battery decrease slightly. When the thickness of the ceramic layer is further reduced (20 μm), the initial efficiency and cycle performance of the all-solid-state battery decrease more seriously.

[0126] 4) By comparing Example 1 and 6, the rolling pressure of the ceramic layer has an effect on its density. Greater rolling pressure is beneficial to improve the density of the ceramic layer, thereby making the all-solid-state battery have stronger pressure resistance, higher initial efficiency and cycle capacity retention rate.

[0127] 5) By comparing Example 1, 9, 10, 11, the particle size of the ceramic particles has a more obvious effect on the Mohs hardness and density of the ceramic layer. With the increase of the particle size of the ceramic particles, the Mohs hardness of the ceramic layer increases, the density decreases, and the initial efficiency and cycle capacity retention rate of the all-solid-state battery also show a gradual downward trend.

[0128] 6) By comparing Example 1, 5, 13, when the temperature of the second heat treatment is reduced (300℃), the density and Mohs hardness of the ceramic layer are reduced, the thickness of the ceramic layer is increased, and the initial efficiency and cycle capacity retention rate of the all-solid-state battery are slightly reduced. When the second heat treatment operation is not used, the Mohs hardness and density of the ceramic layer are significantly reduced, the thickness is significantly increased, which leads to the surface of the all-solid-state battery after isostatic pressing to appear some bending, and the initial efficiency and cycle capacity retention rate are also significantly reduced.

[0129] 7) By comparing Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, the all-solid-state battery of Comparative Example 1 does not include a ceramic layer on the outermost side, and is provided as a conventional negative active material layer. After isostatic pressing, the aluminum plastic film is intact, but the all-solid-state battery is bent obviously, and will be broken during the process of constrained pressing, resulting in short circuit, so that the initial efficiency and cycle performance cannot be tested. When a stainless steel clamp is placed on the surface of the negative active material layer on the outermost side based on Comparative Example 1 (Comparative Example 2), after isostatic pressing, although the surface of the all-solid-state battery is still flat, the aluminum plastic film is broken, resulting in short circuit of the all-solid-state battery, which cannot be cycled. When the stainless steel clamp is replaced from being built-in in the all-solid-state battery to being externally placed on the surface of the aluminum plastic film based on Comparative Example 2, after isostatic pressing, the aluminum plastic film remains intact, but the surface of the battery cell appears some bending, and the externally placed stainless steel clamp is not tightly attached to the internal all-solid-state battery, which makes it difficult to maintain uniform distribution of internal pressure of the all-solid-state battery during the process of constrained pressing, thereby significantly deteriorating the initial efficiency and cycle performance of the all-solid-state battery.

[0130] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, and not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. An all-solid-state battery comprising negative electrode sheets (1) and positive electrode sheets (2) arranged in an interlaced stack, comprising a solid-state electrolyte layer between the negative electrode sheets (1) and the positive electrode sheets (2), wherein, The all-solid-state battery has an outermost negative electrode sheet (1), and the outermost negative electrode sheet (1) includes a negative electrode current collector (11) and a negative electrode active material layer (13) and a ceramic layer (12) disposed on both side surfaces of the negative electrode current collector (11), respectively, and the ceramic layer (12) is located on the side surface of the negative electrode current collector (11) away from the positive electrode sheet (2).

2. The all-solid battery according to claim 1, wherein The ceramic layer (12) satisfies at least one of the following conditions: (1) Mohs hardness is 3-10; (2) Poisson's ratio is 0.1-0.5; (3) Density is 50%-90%; (4) Elastic modulus is 2-10 GPa.

3. The all-solid battery according to claim 1 or 2, wherein The thickness of the ceramic layer (12) is 30-150 μm.

4. The all-solid battery according to claim 1 or 2, wherein The ceramic layer (12) includes ceramic particles and a binder; The mass content of the ceramic particles is 40%-80% and the mass content of the binder is 1%-10% based on the total mass of the ceramic layer (12).

5. The all-solid battery according to claim 4, wherein The ceramic particles include one or more of alumina, zirconia, boehmite, lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium titanium aluminum phosphate, titanium dioxide, silicon carbide, silicon oxide, and silicon nitride.

6. The all-solid battery according to claim 4, wherein The particle size D50 of the ceramic particles is 0.1-3 μm.

7. The all-solid battery according to claim 4, wherein The ceramic layer (12) is prepared by a method including the following steps: The ceramic particles and the binder are mixed in a solvent to obtain a ceramic slurry, the ceramic slurry is coated on one side surface of the negative electrode current collector (11), and the ceramic layer (12) is obtained after heat treatment and roll treatment in sequence.

8. The all-solid battery according to claim 7, wherein The heat treatment includes first heat treatment and second heat treatment in sequence; The temperature of the first heat treatment is 60-200 °C, and the temperature of the second heat treatment is 300-800 °C.

9. The all-solid battery according to claim 7 or 8, wherein The pressure of the roll treatment is 5-50 MPa.

10. A battery pack, wherein, The all-solid-state battery of any one of claims 1-9.

11. An electrical device, comprising: The all-solid-state battery of any one of claims 1-9 or the battery pack of claim 10.

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