Solid-state battery and preparation method thereof

Abstract

The invention relates to the technical field of batteries, in particular to a solid-state battery and a preparation method thereof. The provided solid-state battery comprises a plurality of stacked battery cell units, and each battery cell unit comprises a battery cell body and a coating layer wrapping the outer side of the battery cell body. The preparation method of the solid-state battery comprises the following steps: providing a battery cell body; the outer side of the battery cell body is coated with a coating layer, and the coating layer is made of a soft material; performing isostatic pressing treatment on the battery cell body wrapped with the coating layer to obtain a battery cell unit; and stacking and packaging the plurality of battery cell units to obtain the solid-state battery. According to the invention, serious volume expansion in the battery can be effectively relieved, and the toughness of the battery is improved; moreover, the soft wrapping material outside the battery cell unit does not need to be dismantled after isostatic pressing, the whole battery cell unit can be directly stacked and packaged, the isostatic pressing technological process is simplified, and the battery production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a solid-state battery and a method for preparing the same. Background Art

[0002] Solid-state batteries are considered to be the next generation of battery technology due to their high energy density, high safety and stronger temperature adaptability. However, there are still many problems with solid-state batteries and their manufacturing processes, such as incompatibility with current lithium battery equipment and processes, poor solid-solid interface contact and electrode volume expansion, which restrict their large-scale application.

[0003] Isostatic pressing is suitable for the pressing process of solid-state batteries because of its uniform pressure and the advantage of being able to achieve ultra-high pressure pressing. Therefore, studying the isostatic pressing process of solid-state batteries is an important topic. For example, Nature Energy, 2020, Issue 5, Pages 299-308, reported a method for preparing all-solid-state lithium batteries by warm isostatic pressing; this method vacuum-seals the stacked batteries with a bag for warm isostatic pressing, removes the pressed batteries from the bag, welds the positive and negative pole ears, and then puts them into the bag and vacuum-seals them again.

[0004] At present, some solid-state batteries, such as sulfide all-solid-state batteries, usually use isostatic pressing equipment in the molding process. However, in actual operation, the battery cells need to be packaged in pressure bags and then isostatically pressed. The external pressure bags need to be removed before the battery cells are assembled or tested. This operation is cumbersome and greatly affects the efficiency of isostatic pressing to prepare battery cells.

[0005] In addition, all-solid-state batteries lack toughness because they are made of highly compacted solid materials. They are prone to cracks when the battery is working or under the influence of external forces. In addition, the silicon-based negative electrode materials often used in high-energy-density solid-state batteries have severe expansion and contraction during electrochemical cycles, which can easily cause solid-solid contact failure inside the battery, thereby affecting battery performance. Summary of the invention

[0006] In view of this, the present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the present invention provides a solid-state battery and a preparation method thereof, which can improve the efficiency of isostatic pressing to prepare battery cells, effectively alleviate the serious volume expansion inside the battery, and improve the toughness of the battery.

[0007] In order to solve the above technical problems, this application is implemented as follows:

[0008] According to one aspect of the present application, an embodiment of the present application provides a solid-state battery, which includes a plurality of stacked battery cell units, each of which includes a battery cell body and a coating layer wrapped around the outside of the battery cell body, and the coating layer includes a soft material.

[0009] In some embodiments, the material of the coating layer includes at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide, polytetrafluoroethylene, polyvinyl chloride, polystyrene or polycarbonate.

[0010] In some embodiments, the coating layer is in close contact with the outer surfaces of the battery cell body.

[0011] In some of the embodiments, the battery cell body is provided with a positive electrode tab and a negative electrode tab, at least portions of the positive electrode tab and the negative electrode tab respectively extend outside the coating layer through the openings of the coating layer, and the coating layer wraps the rest of the battery cell body within the coating layer.

[0012] In some embodiments, the battery cell body includes at least one positive electrode sheet, at least one solid electrolyte membrane and at least one negative electrode sheet, and the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked.

[0013] According to another aspect of the present application, an embodiment of the present application provides a method for preparing a solid-state battery, the method comprising:

[0014] Provide the battery cell body;

[0015] Wrapping a coating layer on the outer side of the battery core body, wherein the coating layer is made of soft material;

[0016] The battery cell body wrapped with the coating layer is subjected to isostatic pressing to obtain a battery cell unit;

[0017] A plurality of the battery cell units are stacked and packaged to obtain the solid-state battery.

[0018] In some of the embodiments, the battery cell body is provided with a positive electrode tab and a negative electrode tab, at least portions of the positive electrode tab and the negative electrode tab respectively extend outside the coating layer through the openings of the coating layer, and the coating layer wraps the rest of the battery cell body within the coating layer.

[0019] In some embodiments, the material of the coating layer includes at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide, polytetrafluoroethylene, polyvinyl chloride, polystyrene or polycarbonate.

[0020] In some embodiments, the coating layer is in close contact with the outer surfaces of the battery cell body.

[0021] In some embodiments, the battery cell body includes at least one positive electrode sheet, at least one solid electrolyte membrane and at least one negative electrode sheet, and the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked.

[0022] In some embodiments, providing a battery cell body includes:

[0023] A positive electrode film layer is provided on the surface of the positive electrode current collector by dry rolling or wet coating followed by die cutting to obtain a positive electrode sheet;

[0024] A negative electrode film layer is provided on the surface of the negative electrode current collector by dry rolling or wet coating followed by die cutting to obtain a negative electrode sheet;

[0025] The solid electrolyte membrane is prepared by dry rolling or wet coating with a release film;

[0026] The positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked; wherein the positive electrode film layer in the positive electrode sheet is connected to the solid electrolyte membrane, and the negative electrode film layer in the negative electrode sheet is connected to the solid electrolyte membrane;

[0027] Alternatively, the negative electrode sheet, the solid electrolyte membrane, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane and the negative electrode sheet are stacked;

[0028] Alternatively, the positive electrode sheet, the solid electrolyte membrane, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane and the positive electrode sheet are stacked;

[0029] Alternatively, the negative electrode sheet and the solid electrolyte membrane form a first component, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer and the solid electrolyte membrane form a first assembly, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane and the negative electrode sheet form a second component, and the first component, at least one first assembly and the second component are stacked;

[0030] Alternatively, the positive electrode sheet and the solid electrolyte membrane form a third component, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer and the solid electrolyte membrane form a second assembly, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane and the positive electrode sheet form a fourth assembly, and the third assembly, at least one second assembly and the fourth assembly are stacked.

[0031] In some embodiments, the positive electrode film layer includes a positive electrode active material, an electrolyte material, a conductive agent and a binder.

[0032] In some embodiments, the positive electrode active material includes LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 、ternary material NCM、ternary material NCA、xLi 2 MnO 3 (1-x)LiTMO 2 (TM = one or more of Ni, Mn, Co or Al; 0<x<1), LiMn 2 O 4 , Li 4 Ti 5 O 12 、Li(Ni 0.5 Mn 1.5 ) 4 、LiFePO 4 、LiMnPO 4 、LiNiPO 4 、LiCoPO 4 、LiMn x Fe 1-x PO 4 (0<x<1), high entropy cathode LiNi x Mn y M z O 2 (M includes at least three of Co, Ti, V, Cr, Fe, Zn, Mg, Ca, Ru, Sn, Sb, W, Al, Mo, Y, Nb, La, Ce, Eu or Er, x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1) at least one of.

[0033] In some embodiments, the positive electrode current collector is made of aluminum, nickel, stainless steel, iron, titanium or carbon, and is in the shape of foil or mesh.

[0034] In some embodiments, the negative electrode film layer includes a negative electrode active material, an electrolyte material, a conductive agent and a binder.

[0035] In some embodiments, the negative electrode active material includes at least one of lithium titanate, metallic lithium and its alloys, metallic indium and its alloys, metallic tin and its alloys, carbon-based materials or silicon-based materials.

[0036] In some embodiments, the negative electrode active material includes lithium titanate, metallic lithium, indium, tin and their respective alloys, carbon-based active materials such as graphite, hard carbon, soft carbon, mesophase carbon microbeads, and highly oriented pyrolytic graphite, and at least one of silicon-based active materials such as silicon element, silicon alloy, silicon oxide, and silicon carbon.

[0037] In some embodiments, the negative electrode current collector is copper, stainless steel, nickel or carbon, and is in the shape of foil or mesh.

[0038] In some embodiments, the electrolyte material includes at least one of an oxide solid electrolyte, a halide solid electrolyte, or a sulfide solid electrolyte.

[0039] In some embodiments, the solid electrolyte membrane includes a solid electrolyte, and the solid electrolyte includes at least one of an oxide solid electrolyte, a halide solid electrolyte, or a sulfide solid electrolyte.

[0040] In some embodiments, the electrolyte material or the solid electrolyte comprises an oxide solid electrolyte Li 1+x Al x Ti 2-x (PO 4 ) 3 (0.1≤x≤0.9), Li 7 La 3 Zr 2 O 12 , Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , Li 0.33 La 0.557 TiO 3 , LiPON, halide solid electrolyte Li 3 InCl 6 , Li 2 ZrCl 6 , Li 3 YC 6 or Li 3 ScCl 6 And derivatives of the above compounds, sulfide solid electrolyte Li x MP y S z (M is one or more of Sn, Ge, Si, 0<x, 0<y, 0<z), Li 7-x-y PS 6-x-y Cl x X y 、(X is at least one of the halogen elements F, Br and I, 0≤x, 0≤y), xLi 2 S·(100-x)P 2 S 5 (70≤x≤80) and yLiI·zLiBr·(100-yz)(xLi 2 S·(100-x)P 2 S5 )(70≤x≤80, 0≤y≤30, 0≤z≤30) or a combination of at least two of them.

[0041] In some embodiments, the pressure of the isostatic pressing treatment is 50 MPa to 800 MPa, and the temperature of the isostatic pressing treatment is 25° C. to 250° C.

[0042] In some of the embodiments, after the stacking and before the packaging, the steps of welding the negative electrode tabs and the positive electrode tabs in the plurality of battery cell units together are also included.

[0043] Implementing the technical solution of the present invention has at least the following beneficial effects:

[0044] In the embodiment of the present application, the solid-state battery provided has a coating layer made of soft material on the outside of the battery body, and after isostatic pressing, a battery cell unit can be obtained; thus, on the one hand, by introducing a coating layer of soft material on the outside of the battery body, the coating layer can be used as an intermediate buffer layer of the battery, which can be used to alleviate the internal volume expansion and contraction of the battery, improve the problem of easy brittle fracture of the solid-state battery, and no buffer pad is required in the process of stacking multiple battery cells into a high-capacity battery, which simplifies the stacking process. On the other hand, the coating layer can be used as the external packaging body of the battery cell unit during isostatic pressing, and there is no need to remove it later, that is, the soft coating layer does not need to be removed after isostatic pressing, which can isolate the inside of the unit battery cell from the environment, prevent the side reaction between the battery cell and the environment during the battery assembly process, and improve the production efficiency.

[0045] Additional aspects and advantages of the present application will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Shown is a schematic structural diagram of a battery cell unit provided by an embodiment of the present invention;

[0047] Figure 2 Shown is a schematic structural diagram of a first battery cell body provided by an embodiment of the present invention;

[0048] Figure 3 Shown is a schematic structural diagram of a second battery cell body provided by an embodiment of the present invention;

[0049] Figure 4 FIG. 1 is a schematic structural diagram of a third battery cell body provided by an embodiment of the present invention;

[0050] Figure 5 FIG. 1 is a schematic structural diagram of a fourth battery cell body provided by an embodiment of the present invention;

[0051] Figure 6 FIG. 1 is a schematic structural diagram of a fifth battery cell body provided by an embodiment of the present invention;

[0052] Figure 7 Shown is a schematic structural diagram of a solid-state battery provided in an embodiment of the present invention.

[0053] Description of reference numerals:

[0054] 10-battery cell unit;

[0055] 11-battery body;

[0056] 110-positive electrode sheet; 111-positive electrode film layer; 112-positive electrode current collector; 120-negative electrode sheet; 121-negative electrode film layer; 122-negative electrode current collector; 130-solid electrolyte membrane;

[0057] 113-positive electrode ear; 123-negative electrode ear;

[0058] 140-first component; 150-second component; 160-first assembly; 170-third component; 180-fourth component; 190-second assembly;

[0059] 12- coating layer;

[0060] 20-Package body. DETAILED DESCRIPTION

[0061] The present application is further described below in conjunction with specific embodiments. It should be understood that these embodiments of the present application are only used to illustrate the present application and are not used to limit the scope of the present application.

[0062] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0063] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0064] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0065] As analyzed in the background technology, all-solid-state batteries lack toughness due to the fact that they are all highly compacted solid materials inside. Cracks are prone to appear inside the battery when the battery is working or under the influence of external forces. In addition, the silicon-based negative electrode materials often used in high-energy-density solid-state batteries have serious expansion and contraction in the electrochemical cycle, which can easily cause the solid-solid contact failure inside the battery, thereby affecting the performance of the battery. At present, some solid-state batteries such as sulfide all-solid-state batteries usually use isostatic pressing equipment in the molding process. In actual operation, the battery cell needs to be packaged in a pressure bag and then isostatically pressed. The external pressure bag needs to be removed before the battery cell is assembled or tested. The operation is cumbersome, which greatly affects the efficiency of isostatic pressing to prepare the battery cell, and then affects the production efficiency of solid-state batteries.

[0066] In view of this, in order to alleviate the above problems, the present invention provides a solid-state battery and a method for preparing the solid-state battery, by sealing and wrapping a soft material on the outside of the solid-state battery cell unit, the material having a certain elasticity; then stacking and packaging a plurality of pressed (isostatic pressing) cell units into a solid-state battery, the soft material between the cell units can effectively alleviate the serious volume expansion inside the battery and improve the toughness of the battery; moreover, the coating layer of the soft material on the outside of the cell unit does not need to be removed after isostatic pressing, and the whole can be directly stacked and packaged, which simplifies the isostatic pressing process and improves the battery production efficiency. Next, the application is described in detail.

[0067] See also Figures 1 to 7 As shown, in some embodiments, the present application provides a solid-state battery, which includes a plurality of stacked battery cell units 10, each of which includes a battery cell body 11 and a coating layer 12 wrapped around the outside of the battery cell body 11, and the coating layer 12 includes a soft material.

[0068] The solid-state battery provided in the present application has a coating layer 12 of soft material disposed on the outside of the battery cell unit 10. Wrapping the battery cell body 11 with the coating layer 12 can effectively resist severe volume expansion and contraction inside the battery. No buffer pads are required when stacking the battery cell units into high-capacity batteries, which can simplify the stacking process.

[0069] See also Figures 1 to 7 As shown, in some embodiments, a method for preparing a solid-state battery is provided, the method comprising:

[0070] Providing a battery cell body 11;

[0071] A coating layer 12 is wrapped around the outer side of the battery core body 11, and the coating layer 12 is made of soft material;

[0072] The battery cell body 11 wrapped with the coating layer 12 is subjected to isostatic pressing to obtain a battery cell unit 10;

[0073] A plurality of battery cell units 10 are stacked and packaged to obtain a solid-state battery.

[0074] In the related art, in order to alleviate the problems of expansion and contraction inside the solid-state battery, some buffer material layers are set between the battery cells, such as setting a resin layer, a foam layer or an aerogel layer as an elastic buffer material layer, and the resin layer and other buffer layers are used as buffer materials to inhibit the cracks in the battery cells during manufacturing and alleviate the problems of expansion and contraction inside the battery. However, during the isostatic pressing operation, it is still necessary to set a pressure bag and other wrapping materials on the outside of the battery cell, and there is still a step of removing the pressure bag after pressing. That is, the preparation of solid-state batteries in the prior art cannot take into account the simplification of the isostatic pressing process, the improvement of the efficiency of preparing batteries by the isostatic pressing process, and the effective alleviation of the problem of internal volume expansion of the battery.

[0075] In addition, the prior art sets a buffer material layer between the positive / negative electrode and the electrolyte layer, which can improve the interface resistance and alleviate the volume deformation. However, there is no buffer medium at the edge of the battery, and it cannot achieve the purpose of isolating the battery cell from the environment, that is, it cannot serve as a packaging or wrapping material during isostatic pressing.

[0076] In the present application, a coating layer 12 is disposed on the outer side of the battery cell body 11, and the coating layer 12 can wrap or encapsulate the battery cell body 11, and the coating layer 12 is made of a soft material. Optionally, the soft material of the coating layer 12 has a certain ductility and elasticity, and does not fail under a pressure of about 500 MPa.

[0077] Therefore, the present invention uses a coating layer 12 made of soft material to replace the existing packaging materials (or packaging films) such as pressure bags to encapsulate the battery cell unit 10. The soft material used has a certain ductility and elasticity and does not fail under a pressure of about 500MPa. That is, the strength of the coating layer 12 of the soft material used can meet the requirements of isostatic pressing, and after the pressing is completed, it can be retained in the battery structure as a coating layer 12. Furthermore, it can solve the problem in the prior art that the preparation of solid-state batteries cannot take into account the simplification of the isostatic pressing process, the improvement of the efficiency of preparing batteries by isostatic pressing, and the effective alleviation of the internal volume expansion of the battery.

[0078] Therefore, based on the above arrangement, on the one hand, the present invention can use the coating layer 12 as the intermediate buffer layer of the battery by introducing a coating layer 12 of soft material on the outside of the battery body 11, which can alleviate the internal volume expansion of the battery and improve the problem of easy brittle fracture of the solid-state battery, that is, it can effectively resist the serious volume expansion and contraction inside the battery, and no buffer pad is required in the process of stacking multiple battery cells 10 into a high-capacity battery, which simplifies the stacking process. On the other hand, the coating layer 12 can be used as the external package of the battery cell unit 10 during isostatic pressing, and there is no need to remove it later, that is, the soft coating layer 12 does not need to be removed after isostatic pressing. The coating layer 12 can isolate the inside of the unit battery cell from the environment, prevent the side reaction between the battery cell and the environment during the battery assembly process, and greatly improve the efficiency of preparing the battery cell by the isostatic pressing process, thereby improving the production efficiency of the solid-state battery.

[0079] Optionally, the above-mentioned battery cell body 11 includes a plurality of positive electrode sheets 110, negative electrode sheets 120 and solid electrolyte membranes 130; the above-mentioned providing of the battery cell body 11 is a process of stacking the positive electrode sheets 110, the solid electrolyte membranes 130 and the negative electrode sheets 120 in sequence, or stacking the negative electrode sheets 120, the solid electrolyte membranes 130 and the positive electrode sheets 110 in sequence.

[0080] In the present application, after the battery cell body 11 is prepared, a soft material is wrapped on the outside of the battery cell body 11, that is, a coating layer 12 is provided on the outside of the battery cell body 11, that is, the coating layer 12 can completely encapsulate at least part of the battery cell body 11 in the coating layer 12.

[0081] In some embodiments, the cell body 11 is provided with a positive electrode tab 113 and a negative electrode tab 123, at least a portion of the positive electrode tab 113 and the negative electrode tab 123 respectively extend to the outside of the coating layer 12 through the opening of the coating layer, and the coating layer 12 wraps the rest of the cell body 11 in the coating layer 12. That is, the soft coating layer covering the positive electrode tab 113 and the negative electrode tab 123 needs to be removed so that they extend to the outside of the coating layer respectively, and the coating layer 12 wraps the rest of the cell body 11 in the coating layer 12.

[0082] The above-mentioned battery cell body 11 includes a plurality of positive electrode sheets 110, a negative electrode sheet 120 and a solid electrolyte membrane 130, wherein the positive electrode sheet 110 is provided with or connected to a positive electrode tab 113, and the negative electrode sheet 120 is provided with or connected to a negative electrode tab 123, and the coating layer 12 encapsulates the plurality of positive electrode sheets 110, the negative electrode sheets 120 and the solid electrolyte membrane 130 of the battery cell body 11 in the coating layer 12, and the coating layer 12 is provided with openings for the positive electrode tab 113 and the negative electrode tab 123 to extend outward, that is, the positive electrode tab 113 and the negative electrode tab 123 can extend to the outside of the coating layer 12 respectively through the openings, and the rest of the battery cell body 11 is wrapped by the coating layer 12 inside the coating layer 12.

[0083] Therefore, the present invention provides a completely encapsulated coating layer 12 structure on the outside of the battery body 11, and the coating layer 12 material adopts a soft material with certain ductility and elasticity. During isostatic pressing, it acts as an isolation layer between the isostatic pressing medium (water or oil) and the battery cell. At the same time, the coating layer 12 can improve the edge strength of the battery cell after isostatic pressing to prevent the edge of the battery cell from being brittle. In addition, during the battery assembly process, the coating layer 12 of the battery cell unit 10 can also isolate the side reaction between the environmental moisture and the battery body 11.

[0084] In some embodiments, the material of the coating layer 12, that is, the above-mentioned soft material includes, but is not limited to, any one or a combination of at least two of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polystyrene (PS) or polycarbonate (PC). For the sake of brevity, the combinations within the above range are no longer listed one by one.

[0085] Preferably, the material of the coating layer 12, i.e., the above-mentioned soft material, includes, but is not limited to, any one or a combination of at least two of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide (PA), polytetrafluoroethylene (PTFE), and polyvinyl chloride (PVC). The selection of these soft materials has a wide range of sources, is easy to obtain, is conducive to reducing costs, and meets the required ductility and elasticity, and has a better application effect in the present application.

[0086] The above-mentioned soft material may be but is not limited to PP, PE, PET, PA, PTFE, PVC (such as plastic, rubber, silicone, resin), etc.

[0087] It should be noted that the material of the coating layer 12 can be selected from the above-mentioned polymers, but is not limited to the above-mentioned substances. Other soft materials that can be used to effectively resist severe volume expansion and contraction inside the battery and do not need to be removed after isostatic pressing do not limit the purpose of the present invention. Other similar soft materials can also be used in the present invention.

[0088] In some embodiments, the coating layer 12 is tightly attached to the outer surfaces of the battery cell body 11 .

[0089] In the present application, after the cell body 11 is prepared, the above-mentioned soft material can be wrapped on the outer surface of the cell body 11 , and then vacuuming can be performed to make the coating layer 12 fit tightly with the outer surface of the cell body 11 .

[0090] Optionally, the thickness of the coating layer 12 may range from 0.05 mm to 5 mm; as an example, the thickness of the soft material of the coating layer may be any one of 0.05 mm, 0.1 mm, 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 5 mm or a range between any two of them.

[0091] Therefore, the present application adopts the coating layer 12 of the above-mentioned soft material, which can save the process of adding a buffer layer separately during the battery cell manufacturing process; moreover, the coating layer 12 on the outside of the battery cell unit 10 can directly serve as a pressure bag during isostatic pressing, simplifying the isostatic pressing process and saving the process of battery cell packaging and disassembly of the pressure bag; it can also alleviate the internal volume expansion of the battery and improve the problem of brittle cracking of solid-state batteries.

[0092] In some embodiments, the pressure of the isostatic pressing treatment is 50 MPa to 800 MPa, and the temperature of the isostatic pressing treatment is 25° C. to 250° C. As an example, the pressure of the isostatic pressing treatment can be any one of 50 MPa, 60 MPa, 80 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 40 MPa, 500 MPa, 600 MPa, 700 MPa, and 800 MPa, or a range between any two of them. The temperature of the isostatic pressing treatment can be any one of 25° C., 30° C., 40° C., 50° C., 60° C., 80° C., 100° C., 120° C., 150° C., 200° C., and 250° C., or a range between any two of them.

[0093] It should be pointed out that the present application does not limit the specific process or operation method of isostatic pressing treatment, and the conventional isostatic pressing operation method in the art can be adopted. Other operating conditions of isostatic pressing treatment, such as time, can also be selected and adjusted by technical personnel in this field according to actual conditions, and will not be repeated here.

[0094] As an example, the isostatic pressing process includes: placing the battery cell body 11 wrapped with the coating layer 12 in a flat fixture for isostatic pressing. The pressure of the isostatic pressing is preferably 50MPa to 800MPa, and the temperature of the isostatic pressing is preferably 25°C to 250°C.

[0095] The battery body 11 wrapped with the coating layer 12 is subjected to isostatic pressing in a flat fixture. In the process, a flat fixture is added to the outside of the battery, and the upper and lower surfaces of the battery body 11 wrapped with the coating layer 12 are fixed and then enter the isostatic pressing. After the isostatic pressing treatment is completed, the battery unit 10 is taken out of the flat fixture. The isostatic pressing medium (water or oil) attached to the surface of the battery is removed.

[0096] In some embodiments, after stacking and before packaging, the process further includes welding the negative electrode tabs 123 and the positive electrode tabs 113 in the plurality of battery cell units 10 together.

[0097] Exemplarily, in some embodiments, the method for preparing the solid-state battery specifically includes:

[0098] Step S100: providing a battery cell body 11.

[0099] In some embodiments, the battery cell body 11 includes at least one positive electrode sheet 110 , at least one solid electrolyte membrane 130 , and at least one negative electrode sheet 120 , and the positive electrode sheet 110 , the solid electrolyte membrane 130 , and the negative electrode sheet 120 are stacked.

[0100] It should be noted that in the battery cell body 11, the specific number of positive electrode sheets 110, solid electrolyte membranes 130 and negative electrode sheets 120 can be selected and set according to actual needs. For example, the corresponding number of positive electrode sheets 110, solid electrolyte membranes 130 and negative electrode sheets 120 can be set according to the required capacity of the solid-state battery, and there is no limitation on this.

[0101] In step S100, a battery cell body 11 is provided, mainly by preparing a positive electrode sheet 110, a solid electrolyte membrane 130 and a negative electrode sheet 120 respectively, and then stacking the positive electrode sheet 110, the solid electrolyte membrane 130 and the negative electrode sheet 120 according to a preset battery cell structure to obtain a battery cell body 11.

[0102] As an example, step S100 may include:

[0103] Step S110 , preparing the positive electrode sheet 110 .

[0104] In step S110 , the positive electrode film layer 111 may be disposed on the surface of the positive electrode current collector 112 by dry rolling or wet coating followed by die cutting to obtain the positive electrode sheet 110 .

[0105] Step S120 , preparing the negative electrode sheet 120 .

[0106] In step S120 , the negative electrode film layer 121 may be disposed on the surface of the negative electrode current collector 122 by dry rolling or wet coating followed by die cutting to obtain the negative electrode sheet 120 .

[0107] Step S130 , preparing a solid electrolyte membrane 130 .

[0108] In step S130 , the solid electrolyte membrane 130 may be prepared by dry rolling or wet coating with a release film.

[0109] It should be noted that the solid electrolyte membrane 130 can be made by dry rolling or wet coating on a release film such as a PET film or foil, wherein the solid electrolyte membrane 130 prepared by wet coating needs to be transferred to the negative electrode sheet 120 .

[0110] Step S140: stacking.

[0111] In step S140, after die-cutting, the positive electrode sheet 110, the solid electrolyte membrane 130 and the negative electrode sheet 120 are stacked according to a preset battery cell structure (described in detail later), or the positive electrode collector 112, the positive electrode sheet 110, the solid electrolyte membrane 130, the negative electrode sheet 120 and the negative electrode collector 122 are stacked according to a preset battery cell structure to obtain a battery cell body 11.

[0112] It should be understood that the preparation of the above-mentioned positive electrode sheet 110, negative electrode sheet 120 and solid electrolyte membrane 130 can be carried out by a dry method or a wet method known in the prior art. The specific preparation process of the dry method or the wet method can be carried out in a conventional manner and will not be repeated here.

[0113] Step S200 , wrapping the outer side of the battery cell body 11 with a coating layer 12 , wherein the coating layer 12 is made of the above-mentioned soft material.

[0114] Step S300 , subjecting the battery cell body 11 wrapped with the coating layer 12 to isostatic pressing treatment, wherein the pressure of the isostatic pressing treatment is preferably 50 MPa to 800 MPa, and the temperature of the isostatic pressing treatment is preferably 25° C. to 250° C., to obtain a battery cell unit 10 .

[0115] Step S400, stacking a plurality of battery cell units 10, and then performing tab welding, that is, welding the negative electrode tabs 123 and the positive electrode tabs 113 in the plurality of battery cell units 10 together, and then performing packaging to obtain a solid-state battery.

[0116] In the present application, the specific structure of the battery cell body 11 may have various forms, including but not limited to the material structure forms listed below. That is, in step S140, in order to meet different practical application requirements, the positive electrode sheet 110, the solid electrolyte membrane 130 and the negative electrode sheet 120 may be stacked in various ways, and the specific number of the positive electrode sheet 110, the solid electrolyte membrane 130 and the negative electrode sheet 120 may also be selected and set according to different requirements.

[0117] As an example, in a first embodiment, if Figure 2As shown, in step S140, the positive electrode sheet 110, the solid electrolyte membrane 130 and the negative electrode sheet 120 are stacked; wherein the positive electrode film layer 111 in the positive electrode sheet 110 is connected to the solid electrolyte membrane 130, and the negative electrode film layer 121 in the negative electrode sheet 120 is connected to the solid electrolyte membrane 130. That is, in the battery body 11, the positive electrode collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130, the negative electrode film layer 121, and the negative electrode collector 122 are stacked in sequence.

[0118] In a second embodiment, if Figure 3 As shown, in step S140, the negative electrode sheet 120, the solid electrolyte membrane 130, the positive electrode film layer 111, the positive electrode current collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130 and the negative electrode sheet 120 are stacked. That is, in the battery body 11, the negative electrode current collector 122, the negative electrode film layer 121, the solid electrolyte membrane 130, the positive electrode film layer 111, the positive electrode current collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130, the negative electrode film layer 121 and the negative electrode current collector 122 are stacked in sequence.

[0119] In a third embodiment, if Figure 4 As shown, in step S140, the positive electrode sheet 110, the solid electrolyte membrane 130, the negative electrode film layer 121, the negative electrode current collector 122, the negative electrode film layer 121, the solid electrolyte membrane 130 and the positive electrode sheet 110 are stacked. That is, in the battery body 11, the positive electrode current collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130, the negative electrode film layer 121, the negative electrode current collector 122, the negative electrode film layer 121, the solid electrolyte membrane 130, the positive electrode film layer 111 and the positive electrode current collector 112 are stacked in sequence.

[0120] In a fourth embodiment, if Figure 5 As shown, in step S140, the negative electrode sheet 120 and the solid electrolyte membrane 130 are formed into a first component 140, the positive electrode film layer 111, the positive electrode collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130, the negative electrode film layer 121, the negative electrode collector 122, the negative electrode film layer 121 and the solid electrolyte membrane 130 are formed into a first assembly 160, the positive electrode film layer 111, the positive electrode collector 112, the positive electrode film layer 111, the solid electrolyte membrane 130 and the negative electrode sheet 120 are formed into a second component 150, and the first component 140, at least one first assembly 160 and the second component 150 are stacked; wherein the first assembly 160 can be repeated multiple times between the first component 140 and the second component 150, for example, one or more first assemblies 160 can be arranged between the first component 140 and the second component 150.

[0121] That is, in the battery cell body 11, the first component 140, one or more first assemblies 160 and the second component 150 are stacked in sequence. The first component 140 includes a stacked negative electrode current collector 122, a negative electrode film layer 121 and a solid electrolyte film 130, the first assembly 160 includes a stacked positive electrode film layer 111, a positive electrode current collector 112, a positive electrode film layer 111, a solid electrolyte film 130, a negative electrode film layer 121, a negative electrode current collector 122, a negative electrode film layer 121 and a solid electrolyte film 130, and the second component 150 includes a stacked positive electrode film layer 111, a positive electrode current collector 112, a positive electrode film layer 111, a solid electrolyte film 130, a negative electrode film layer 121 and a negative electrode current collector 122.

[0122] In a fifth embodiment, if Figure 6 As shown, in step S140, the positive electrode sheet 110 and the solid electrolyte membrane 130 are formed into a third component, the negative electrode film layer 121, the negative electrode current collector 122, the negative electrode film layer 121, the solid electrolyte membrane 130, the positive electrode film layer 111, the positive electrode current collector 112, the positive electrode film layer 111 and the solid electrolyte membrane 130 are formed into a second assembly 190, and the negative electrode film layer 121, the negative electrode current collector 122, the negative electrode film layer 121, the solid electrolyte membrane 130 and the positive electrode sheet 110 are formed into a fourth assembly 180, and the third assembly, at least one second assembly 190 and the fourth assembly 180 are stacked; wherein the second assembly 190 can be repeated multiple times between the third assembly and the fourth assembly 180, for example, one or more second assemblies 190 can be arranged between the third assembly 170 and the fourth assembly 180.

[0123] That is, in the battery cell body 11, the third component 170, one or more second assemblies 190 and the fourth component 180 are stacked in sequence. Among them, the third component 170 includes a stacked positive electrode current collector 112, a positive electrode film layer 111 and a solid electrolyte film 130, the second assembly 190 includes a negative electrode film layer 121, a negative electrode current collector 122, a negative electrode film layer 121, a solid electrolyte film 130, a positive electrode film layer 111, a positive electrode current collector 112, a positive electrode film layer 111 and a solid electrolyte film 130, and the fourth component 180 includes a stacked negative electrode film layer 121, a negative electrode current collector 122, a negative electrode film layer 121, a solid electrolyte film 130, a positive electrode film layer 111 and a positive electrode current collector 112.

[0124] Optionally, in the present application, the shapes of the positive electrode film layer 111 , the negative electrode film layer 121 , the solid electrolyte membrane 130 , the positive electrode current collector 112 and the negative electrode current collector 122 are not clearly specified and may be polygonal or circular.

[0125] In some embodiments, the positive electrode film layer 111 includes a positive electrode active material, an electrolyte material, a conductive agent, and a binder.

[0126] Optionally, in the positive electrode film layer 111 , the mass ratio of the positive electrode active material, the electrolyte material, the conductive agent and the binder is (50-90): (1-50): (0.1-15): (0.1-15).

[0127] In some embodiments, the positive electrode active material includes, but is not limited to, LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 、ternary material NCM、ternary material NCA、xLi 2 MnO 3 (1-x)LiTMO 2 (TM = one or more of Ni, Mn, Co or Al; 0<x<1), LiMn 2 O 4 , Li 4 Ti 5 O 12 、Li(Ni 0.5 Mn 1.5 ) 4 、LiFePO 4 、LiMnPO 4 、LiNiPO 4 、LiCoPO 4 、LiMn x Fe 1- x PO 4 (0<x<1), high entropy cathode LiNi x Mn y M z O 2 (M includes at least three of Co, Ti, V, Cr, Fe, Zn, Mg, Ca, Ru, Sn, Sb, W, Al, Mo, Y, Nb, La, Ce, Eu or Er, x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1) any one or a combination of at least two.

[0128] As an example, in the positive electrode film layer 111, the positive electrode active material may be LiCoO 2 , can be LiMnO 2 , can be LiNiO 2 , which can be LiVO 2 , can be LiMn 2 O 4 , can be Li 4 Ti 5 O 12 , which can be Li(Ni 0.5 Mn1.5 ) 4 , can be LiFePO 4 , which can be LiMnPO 4 , which can be LiNiPO 4 , which can be LiCoPO 4 , can be LiMn x Fe 1-x PO 4 (0<x<1);

[0129] Or it can also be a ternary material NCM, the ternary material NCM is LiNi x Co y Mn z O 2 , where x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1;

[0130] Or it can also be a ternary material NCA, the ternary material NCA is LiNi x Co y Al z O 2 , where x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1;

[0131] Or it can also be xLi 2 MnO 3 (1-x)LiTMO 2 , wherein TM = any one or more combinations of Ni, Mn, Co, and Al; 0<x<1;

[0132] Or it can also be a high entropy cathode LiNi x Mn y M z O 2 , wherein M includes at least three of Co, Ti, V, Cr, Fe, Zn, Mg, Ca, Ru, Sn, Sb, W, Al, Mo, Y, Nb, La, Ce, Eu or Er, and x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1.

[0133] However, the present application is not limited to these positive electrode active materials, and other traditional materials or improved positive electrode active materials that can be used as positive electrode active materials for batteries can also be used in the present application. The above-mentioned positive electrode active materials can be used alone or in combination of two or more.

[0134] In some embodiments, the positive electrode current collector 112 is made of aluminum, nickel, stainless steel, iron, titanium or carbon, and is in the shape of foil or mesh.

[0135] In some embodiments, the negative electrode film layer 121 includes a negative electrode active material, an electrolyte material, a conductive agent, and a binder.

[0136] Optionally, in the negative electrode film layer 121 , the mass ratio of the negative electrode active material, the electrolyte material, the conductive agent and the binder is (50-90): (1-50): (0.1-15): (0.1-15).

[0137] In some embodiments, the negative electrode active material includes, but is not limited to, any one of lithium titanate, metallic lithium and its alloys, metallic indium and its alloys, metallic tin and its alloys, carbon-based materials or silicon-based materials, or a combination of at least two thereof.

[0138] As an example, the negative electrode active material can be lithium titanate, metallic lithium (Li), indium (In), tin (Sn) and their respective alloys, carbon-based active materials such as graphite, hard carbon, soft carbon, mesophase carbon microbeads, and highly oriented pyrolytic graphite, and any one or a combination of at least two of silicon (Si) elemental, silicon (Si) alloys, silicon oxide, and silicon carbon silicon (Si)-based active materials.

[0139] However, the present application is not limited to these negative electrode active materials, and other traditional materials or improved negative electrode active materials that can be used as negative electrode active materials for batteries can also be used in the present application. The above-mentioned negative electrode active materials can be used alone or in combination of two or more.

[0140] In some embodiments, the negative electrode current collector 122 is made of copper, stainless steel, nickel or carbon, and is in the shape of foil or mesh.

[0141] In the present application, electrolyte materials are added to both the negative electrode film layer 121 and the positive electrode film layer 111 . The addition of electrolyte materials can enhance the lithium ion transport in a composite electrode such as a composite positive electrode or a composite negative electrode.

[0142] Optionally, the electrolyte materials in the negative electrode film layer 121 and the positive electrode film layer 111 may be the same or different, but are preferably the same.

[0143] In some embodiments, the electrolyte material includes any one of an oxide solid electrolyte, a halide solid electrolyte, or a sulfide solid electrolyte, or a combination of at least two thereof.

[0144] As an example, the electrolyte material in the positive electrode film layer 111 and the negative electrode film layer 121 can be an oxide solid electrolyte, such as Li 1+x Al x Ti 2-x (PO 4 ) 3 (0.1≤x≤0.9), Li 7 La 3 Zr2 O 12 , Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , Li 0.33 La 0.557 TiO 3 、LiPON;

[0145] Or it can be a halide solid electrolyte, such as Li 3 InCl 6 , Li 2 ZrCl 6 , Li 3 YC 6 or Li 3 ScCl 6 and derivatives of the above compounds;

[0146] Or it can be a sulfide solid electrolyte, such as Li x MP y S z (M is one or more of Sn, Ge, Si, 0<x, 0<y, 0<z), Li 7-x-y PS 6-x-y Cl x X y 、(X is at least one of the halogen elements F, Br and I, 0≤x, 0≤y), xLi 2 S·(100-x)P 2 S 5 (70≤x≤80) and yLiI·zLiBr·(100-yz)(xLi 2 S·(100-x)P 2 S 5 )(70≤x≤80, 0≤y≤30, 0≤z≤30) or a combination of at least two of them.

[0147] It should be noted that the present invention has no particular restrictions on the types of conductive agents and binders in the negative electrode film layer 121 and the positive electrode film layer 111, as long as the purpose of the present application can be achieved. For example, in some embodiments, the binder can be one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), nitrile rubber (NBR), styrene butadiene latex (SBR), and carboxymethyl cellulose (CMC). The conductive agent can be one or more of conductive carbon black, carbon nanotubes (CNTs), carbon nanofibers (CNFs), and vapor grown carbon fibers (VGCFs).

[0148] In some embodiments, the solid electrolyte membrane 130 includes a solid electrolyte including at least one of an oxide solid electrolyte, a halide solid electrolyte, or a sulfide solid electrolyte.

[0149] In the present application, the solid electrolyte in the solid electrolyte membrane 130 may be of the same type as or different from the electrolyte material in the negative electrode film layer 121 and the positive electrode film layer 111 .

[0150] Optionally, the solid electrolyte membrane 130 further includes a binder, that is, the solid electrolyte membrane 130 is mainly composed of a solid electrolyte and a binder.

[0151] In some embodiments, the solid electrolyte includes an oxide solid electrolyte Li 1+x Al x Ti 2-x (PO 4 ) 3 (0.1≤x≤0.9), Li 7 La 3 Zr 2 O 12 , Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , Li 0.33 La 0.557 TiO 3 , LiPON, halide solid electrolyte Li 3 InCl 6 , Li 2 ZrCl 6 , Li 3 YC 6 or Li 3 ScCl 6 And derivatives of the above compounds, sulfide solid electrolyte Li x MP y S z (M is one or more of Sn, Ge, Si, 0<x, 0<y, 0<z), Li 7-x-y PS 6-x-y Cl x X y 、(X is at least one of the halogen elements F, Br and I, 0≤x, 0≤y), xLi 2 S·(100-x)P 2 S 5 (70≤x≤80) and yLiI·zLiBr·(100-yz)(xLi 2 S·(100-x)P 2 S5 )(70≤x≤80, 0≤y≤30, 0≤z≤30) or a combination of at least two of them.

[0152] In some embodiments, the present application provides a solid-state battery, which is prepared by the aforementioned solid-state battery preparation method.

[0153] In the present application, the solid-state battery includes a plurality of stacked battery cell units 10 , and each battery cell unit 10 includes a battery cell body 11 and a coating layer wrapped around the outside of the battery cell body 11 .

[0154] Optionally, the solid-state battery may also be disposed in a packaging body 20 outside the plurality of battery cell units 10 .

[0155] The present application does not limit the structural type of solid-state batteries. For example, the battery structure of the present application includes but is not limited to soft-pack batteries, square hard-shell batteries or cylindrical hard-shell batteries.

[0156] It should be understood that all the features and advantages described above for the “method for preparing a solid-state battery” are also applicable to the “solid-state battery” and will not be elaborated here one by one.

[0157] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this area or the product instructions are used. If the manufacturer of the reagents, materials or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0158] Example 1

[0159] A method for preparing a solid-state battery comprises the following steps:

[0160] Step S100: positive electrode active material NCM, sulfide electrolyte Li 6 PS 5 Cl, conductive agent VGCF, and binder PTFE were mixed in a mass ratio of 80:16.5:3:0.5, rolled, and die-cut to obtain a positive electrode film. Carbon-coated aluminum foil was die-cut to obtain a positive electrode current collector.

[0161] The negative electrode active material graphite, sulfide electrolyte Li 6 PS 5 Cl, conductive agent VGCF, and binder PTFE were mixed in a mass ratio of 70:26.5:3:0.5, rolled, and die-cut to obtain a negative electrode film. Carbon-coated copper foil was die-cut to obtain a negative electrode current collector.

[0162] The sulfide electrolyte LPSCl and the binder PTFE were mixed in a mass ratio of 99.5:0.5 and then rolled and die-cut to obtain a solid electrolyte membrane.

[0163] The battery cell body is stacked in the order of positive electrode collector, positive electrode film, solid electrolyte membrane, negative electrode film, negative electrode collector, negative electrode film, solid electrolyte membrane, positive electrode film and positive electrode collector.

[0164] Step S200: After stacking, a soft coating layer made of polypropylene is encapsulated on the outside of the battery body, and the battery body wrapped with the soft coating layer is subjected to isostatic pressing in a flat fixture, with an isostatic pressing pressure of 500MPa, a time of 10min, and a temperature of 60°C. After the isostatic pressing treatment, the battery cell is taken out of the flat fixture, and the isostatic pressing medium (water) attached to the surface of the battery cell is dried. The soft coating layer covering the positive and negative pole ears is removed, so that the ears extend outside the coating layer, and the rest of the battery body is in the coating layer. Thus, a battery cell unit is obtained.

[0165] Step S300, stacking two battery cell units, welding the positive electrode tab and the negative electrode tab respectively; finally encapsulating the external aluminum-plastic film to obtain an all-solid-state battery.

[0166] Example 2

[0167] Embodiment 2 is substantially the same as Embodiment 1, except that:

[0168] In step S300, four battery cell units are stacked;

[0169] The rest are the same as in Example 1.

[0170] Example 3

[0171] Embodiment 3 is substantially the same as Embodiment 1, except that:

[0172] In step S300, six battery cell units are stacked;

[0173] The rest are the same as in Example 1.

[0174] Example 4

[0175] Embodiment 4 is substantially the same as Embodiment 1, except that:

[0176] In step S200, the soft material of the soft coating layer is polyethylene;

[0177] The rest are the same as in Example 1.

[0178] Comparative Example 1

[0179] Comparative Example 1 is substantially the same as Example 1, except that:

[0180] In step S200, after stacking, the battery cells are packaged in an aluminum-plastic film, and the battery cells are subjected to isostatic pressing in a flat fixture at an isostatic pressing pressure of 500 MPa, a time of 10 min, and a temperature of 60° C. After the isostatic pressing treatment, the battery cells are taken out of the flat fixture, and the aluminum-plastic film wrapping the battery cells is removed to obtain a battery cell unit.

[0181] The rest are the same as in Example 1.

[0182] Comparative Example 2

[0183] Comparative Example 2 is substantially the same as Example 2, except that:

[0184] In step S200, after stacking, the battery cells are packaged in an aluminum-plastic film, and the battery cells are subjected to isostatic pressing in a flat fixture at an isostatic pressing pressure of 500 MPa, a time of 10 min, and a temperature of 60° C. After the isostatic pressing treatment, the battery cells are taken out of the flat fixture, and the aluminum-plastic film wrapping the battery cells is removed to obtain a battery cell unit.

[0185] The rest are the same as in Example 2.

[0186] Comparative Example 3

[0187] Comparative Example 3 is substantially the same as Example 3, except that:

[0188] In step S200, after stacking, the battery cells are packaged in an aluminum-plastic film, and the battery cells are subjected to isostatic pressing in a flat fixture at an isostatic pressing pressure of 500 MPa, a time of 10 min, and a temperature of 60° C. After the isostatic pressing treatment, the battery cells are taken out of the flat fixture, and the aluminum-plastic film wrapping the battery cells is removed to obtain a battery cell unit.

[0189] The rest is the same as Example 3.

[0190] Performance Testing

[0191] The solid-state batteries prepared in the above-mentioned embodiments and comparative examples were subjected to performance tests, specifically including:

[0192] The all-solid-state battery is pressurized to 10Mpa in the test fixture and the battery performance is tested in a 60°C environment. The battery is observed to see if it is short-circuited or open-circuited, and the first cycle charge and discharge performance of the battery is tested at 0.1C.

[0193] The test results are shown in Table 1.

[0194] Table 1 is the evaluation results of the battery cells prepared in the examples and comparative examples

[0195] Battery preparation success rate Battery discharge capacity Example 1 100％ 187mAh / g Example 2 100％ 179mAh / g Example 3 90％ 176mAh / g Example 4 100％ 184mAh / g Comparative Example 1 70％ 163mAh / g Comparative Example 2 60％ 155mAh / g Comparative Example 3 60％ 150mAh / g

[0196] Table 1 shows the evaluation results of the battery cells prepared in the examples and comparative examples, wherein 10 batteries were prepared in each example or comparative example, and Table 1 presents the data of the battery preparation success rate and battery discharge capacity under different implementation methods. The success rate is calculated by dividing the number of batteries without short circuit and disconnection by 10 and multiplying by 100%, and the battery discharge capacity is the average discharge capacity of batteries without short circuit and disconnection.

[0197] It can be seen from the data in Table 1 that, compared with Comparative Examples 1-3, the solid-state batteries prepared by the methods of Examples 1-4 of the present invention have improved the discharge specific capacity of the batteries and increased the success rate of battery preparation; and, compared with Comparative Examples 1-3, the methods of the embodiments of the present invention avoid the need to remove wrapping materials such as aluminum-plastic films after the isostatic pressing operation, thereby simplifying the isostatic pressing operation process and improving production efficiency.

[0198] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0199] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0200] It should be noted that the term "and / or" or " / " used in this document is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The singular forms of "a", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0201] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A, B are listed, the phrase "at least one of A, B" means only A; only B; or A and B. In another example, if items A, B, C are listed, the phrase "at least one of A, B, C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0202] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid-state battery, characterized in that: The solid-state battery includes a plurality of stacked battery cell units, each of which includes a battery cell body and a coating layer wrapped around the outside of the battery cell body, and the coating layer includes a soft material.

2. The solid-state battery according to claim 1, characterized in that: The material of the coating layer includes at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide, polytetrafluoroethylene, polyvinyl chloride, polystyrene or polycarbonate; And / or, the coating layer is in close contact with the outer surfaces of the battery cell body.

3. The solid-state battery according to claim 1, characterized in that: The battery cell body is provided with a positive electrode tab and a negative electrode tab, at least parts of the positive electrode tab and the negative electrode tab extend outside the coating layer through the openings of the coating layer respectively, and the coating layer wraps the rest of the battery cell body within the coating layer.

4. The solid-state battery according to any one of claims 1 to 3, characterized in that: The battery cell body comprises at least one positive electrode sheet, at least one solid electrolyte membrane and at least one negative electrode sheet, and the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked.

5. A method for preparing a solid-state battery, characterized in that: The method comprises: Provide the battery cell body; Wrapping a coating layer on the outer side of the battery core body, wherein the coating layer is made of soft material; The battery cell body wrapped with the coating layer is subjected to isostatic pressing to obtain a battery cell unit; A plurality of the battery cell units are stacked and packaged to obtain the solid-state battery.

6. The method for preparing a solid-state battery according to claim 5, characterized in that: The material of the coating layer includes at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide, polytetrafluoroethylene, polyvinyl chloride, polystyrene or polycarbonate; And / or, the coating layer is in close contact with the outer surfaces of the battery cell body; And / or, the battery cell body is provided with a positive electrode tab and a negative electrode tab, at least parts of the positive electrode tab and the negative electrode tab respectively extend outside the coating layer through the openings of the coating layer, and the coating layer wraps the rest of the battery cell body within the coating layer. And / or, the battery cell body includes at least one positive electrode sheet, at least one solid electrolyte membrane and at least one negative electrode sheet, and the positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked.

7. The method for preparing a solid-state battery according to claim 6, characterized in that: The providing of the battery cell body comprises: A positive electrode film layer is provided on the surface of the positive electrode current collector by dry rolling or wet coating followed by die cutting to obtain a positive electrode sheet; A negative electrode film layer is provided on the surface of the negative electrode current collector by dry rolling or wet coating followed by die cutting to obtain a negative electrode sheet; The solid electrolyte membrane is prepared by dry rolling or wet coating with a release film; The positive electrode sheet, the solid electrolyte membrane and the negative electrode sheet are stacked; wherein the positive electrode film layer in the positive electrode sheet is connected to the solid electrolyte membrane, and the negative electrode film layer in the negative electrode sheet is connected to the solid electrolyte membrane; Alternatively, the negative electrode sheet, the solid electrolyte membrane, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane and the negative electrode sheet are stacked; Alternatively, the positive electrode sheet, the solid electrolyte membrane, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane and the positive electrode sheet are stacked; Alternatively, the negative electrode sheet and the solid electrolyte membrane form a first component, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer and the solid electrolyte membrane form a first assembly, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer, the solid electrolyte membrane and the negative electrode sheet form a second component, and the first component, at least one first assembly and the second component are stacked; Alternatively, the positive electrode sheet and the solid electrolyte membrane form a third component, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane, the positive electrode film layer, the positive electrode current collector, the positive electrode film layer and the solid electrolyte membrane form a second assembly, the negative electrode film layer, the negative electrode current collector, the negative electrode film layer, the solid electrolyte membrane and the positive electrode sheet form a fourth assembly, and the third assembly, at least one second assembly and the fourth assembly are stacked.

8. The method for preparing a solid-state battery according to claim 7, characterized in that: The positive electrode film layer comprises a positive electrode active material, an electrolyte material, a conductive agent and a binder; And / or, the negative electrode film layer comprises a negative electrode active material, an electrolyte material, a conductive agent and a binder; The positive electrode active material includes LiCoO2, LiMnO2, LiNiO2, LiVO2, ternary material NCM, ternary material NCA, xLi2MnO3·(1-x)LiTMO2 (TM=one or more of Ni, Mn, Co or Al; 0<x<1), LiMn2O4, Li4Ti5O 12 、Li(Ni 0.5 Mn 1.5 )O4, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiMn x Fe 1-x PO4(0<x<1), high entropy cathode LiNi x Mn y M z O2 (M includes at least three of Co, Ti, V, Cr, Fe, Zn, Mg, Ca, Ru, Sn, Sb, W, Al, Mo, Y, Nb, La, Ce, Eu or Er, x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1); The negative electrode active material includes at least one of lithium titanate, metallic lithium and its alloys, metallic indium and its alloys, metallic tin and its alloys, carbon-based materials or silicon-based materials; The electrolyte material includes at least one of an oxide solid electrolyte, a halide solid electrolyte or a sulfide solid electrolyte; And / or, the solid electrolyte membrane includes a solid electrolyte, and the solid electrolyte includes at least one of an oxide solid electrolyte, a halide solid electrolyte or a sulfide solid electrolyte.

9. The method for preparing a solid-state battery according to any one of claims 5 to 8, characterized in that: The pressure of the isostatic pressing treatment is 50 MPa to 800 MPa, and the temperature of the isostatic pressing treatment is 25° C. to 250° C.

10. The method for preparing a solid-state battery according to any one of claims 5 to 8, characterized in that: After the stacking and before the packaging, the method further includes welding the negative electrode tabs and the positive electrode tabs in the plurality of battery core units together.

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