Tab-free battery cell, preparation method thereof and solid-state battery

Abstract

The invention relates to a tab-free battery cell, a preparation method thereof and a solid-state battery, the tab-free battery cell comprises a tab-free battery cell unit, and the tab-free battery cell unit comprises a tab-free battery cell assembly and a conductive buffer plate which are stacked; the tab-free battery cell assembly comprises a first current collector, a positive plate, an electrolyte plate, a negative plate and a second current collector which are stacked in sequence; the first current collector and the second current collector are lug-free current collectors; the conductive buffer sheet comprises a conductor and a buffer area; the buffer region comprises an insulating substance; the electric conductor comprises a built-in conductor and an external conductor; the external conductor at least partially extends out of the edge of the conductive buffer sheet; the conductor is of a sheet-shaped structure, and the buffer area surrounds the periphery of the built-in conductor; and / or the conductor is of a net structure, and the insulating substance is filled in at least part of pores of the net structure. The influence of edge shearing force on the tabs does not need to be considered in the battery cell pressing process, and the battery design is more flexible when the battery cell units without the tabs are stacked into the solid-state battery in the later period.

Description

Technical Field

[0001] The present invention relates to the field of new energy batteries, and in particular to a tab-free battery cell and a preparation method thereof, and a solid-state battery. Background Art

[0002] Compared with traditional liquid batteries, solid-state batteries have higher safety, higher energy density, wider operating temperature range, longer cycle life and higher design flexibility. Unlike the solid-liquid contact between the active material and the electrolyte in liquid batteries, the active material and the electrolyte in solid-state batteries are in solid-solid contact. In order to ensure the effective transmission of lithium ions in solid-state batteries, it is necessary to increase the contact area between the active material and the electrolyte. Usually, the battery cell is subjected to isostatic pressing or roller pressing to increase the compaction density inside the battery and improve lithium ion transmission. However, due to the sudden change in thickness at the connection between the tab and the main body of the battery cell in solid-state batteries, the root of the tab will break under the action of shear force during the pressing process, causing the battery to short-circuit. Summary of the invention

[0003] In view of this, the present invention is committed to providing a tab-free battery cell and a preparation method thereof and a solid-state battery, so as to solve the problem in the prior art that the shear force at the tab is large and easily causes the tab to break due to the sudden change in thickness during the pressing process of the all-solid-state battery.

[0004] In order to solve the above technical problems, this application is implemented as follows:

[0005] A first aspect of the present invention provides a tab-free battery cell, wherein the tab-free battery cell comprises a tab-free battery cell unit, wherein the tab-free battery cell unit comprises a stacked tab-free battery cell assembly and a conductive buffer sheet;

[0006] Wherein, the tab-free battery core assembly comprises a first current collector, a positive electrode sheet, an electrolyte sheet, a negative electrode sheet, and a second current collector stacked in sequence; the first current collector and the second current collector are tab-free current collectors;

[0007] The conductive buffer sheet comprises a conductor and a buffer area; the buffer area comprises a first insulating material; the conductor comprises an internal conductor and an external conductor; the external conductor at least partially extends to the outside of the edge of the conductive buffer sheet;

[0008] The conductor is a sheet structure, and the buffer area surrounds the built-in conductor; and / or the conductor is a mesh structure, and the first insulating material is filled in at least part of the pores of the mesh structure.

[0009] Optionally, the built-in conductor and the external conductor are integrally formed; the conductor is a foil conductor and / or a mesh conductor; optionally, the material of the conductor is selected from at least one of stainless steel, copper, aluminum, nickel and carbon.

[0010] Optionally, the specific surface area of ​​the buffer region is 0 to 99% of the total specific surface area of ​​the conductive buffer sheet; preferably, the specific surface area of ​​the buffer region is 30 to 95% of the total specific surface area of ​​the conductive buffer sheet; optionally, the first insulating material is selected from at least one of silica gel, polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride.

[0011] Optionally, the positive electrode sheet comprises a positive electrode active material region and a positive electrode stress dispersion region, wherein the positive electrode active material region is located in the central region of the positive electrode sheet, and the positive electrode stress dispersion region surrounds the positive electrode active material region; optionally, the specific surface area of ​​the positive electrode stress dispersion region is 0 to 30% of the total specific surface area of ​​the positive electrode sheet, preferably, the specific surface area of ​​the positive electrode stress dispersion region is 0.1 to 10% of the total specific surface area of ​​the positive electrode sheet; optionally, the positive electrode stress dispersion region comprises a second insulating material; the second insulating material comprises an inorganic material and / or an organic material, the organic material is selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material is selected from Al 2 O 3 , AlN, γ-AlOOH, an oxide solid electrolyte, a halide solid electrolyte and a sulfide solid electrolyte.

[0012] Optionally, the negative electrode sheet comprises a negative electrode active material region and a negative electrode stress dispersion region, wherein the negative electrode active material region is located in the central region of the negative electrode sheet, and the negative electrode stress dispersion region surrounds the negative electrode active material region; optionally, the specific surface area of ​​the negative electrode stress dispersion region is 0 to 30% of the total specific surface area of ​​the negative electrode sheet, preferably, the specific surface area of ​​the negative electrode stress dispersion region is 0.1 to 10% of the total specific surface area of ​​the negative electrode sheet; optionally, the negative electrode stress dispersion region comprises a third insulating material; the third insulating material comprises an inorganic material and / or an organic material, the organic material is selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material is selected from Al 2 O 3 , AlN, γ-AlOOH, an oxide solid electrolyte, a halide solid electrolyte and a sulfide solid electrolyte.

[0013] Optionally, the first current collector and the second current collector are each independently selected from a foil current collector and / or a mesh current collector, and the material of the first current collector and the second current collector are each independently selected from at least one of stainless steel, copper, aluminum, nickel and carbon.

[0014] A second aspect of the present invention provides a method for preparing a tab-free battery cell, the method comprising the following steps:

[0015] S1, stacking and pressing the first current collector, the positive electrode sheet, the electrolyte sheet, the negative electrode sheet and the second current collector to obtain a tab-free battery cell assembly;

[0016] S2, assembling the conductor and the buffer material to obtain a conductive buffer sheet;

[0017] S3, stacking the conductive buffer sheet and the tab-free battery cell assembly to obtain a tab-free battery cell unit.

[0018] Optionally, the compaction densification comprises at least one of isostatic pressing, flat plate pressing and roller pressing.

[0019] Optionally, the method for preparing the tab-free battery cell further comprises: stacking a plurality of the tab-free battery cell units to obtain the tab-free battery cell.

[0020] A third aspect of the present invention provides a solid-state battery, comprising a battery cell, wherein the battery cell is the above-mentioned tab-free battery cell and / or the tab-free battery cell prepared according to the above-mentioned preparation method.

[0021] Through the above technical scheme, the beneficial technical effect of the present invention is: the tab-free battery cell unit of the present invention includes stacked tab-free battery cell components and conductive buffer sheets. During the battery cell pressing process, there is no need to consider the influence of edge shear force on the tabs. The battery design is more flexible when the tab-free battery cell units are stacked into solid-state batteries in the later stage.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0024] Figure 1 A first specific embodiment of the solid-state battery of the present invention is shown.

[0025] Figure 2 A second specific embodiment of the solid-state battery of the present invention is shown.

[0026] Figure 3 The first specific embodiment of the conductive buffer sheet of the present invention is shown.

[0027] Figure 4 The second specific embodiment of the conductive buffer sheet of the present invention is shown.

[0028] Figure 5 The third specific embodiment of the conductive buffer sheet of the present invention is shown.

[0029] Figure 6 A preferred embodiment of the positive electrode sheet of the present invention is shown.

[0030] Figure 7 A preferred embodiment of the negative electrode sheet of the present invention is shown.

[0031] Figure 8 The figure shows the cell structure prepared in Example 1.

[0032] Fig. 9 The figure shows the cell structure prepared in Example 2.

[0033] Fig.10 The figure shows the cell structure prepared in Example 3.

[0034] Fig.11 The figure shows the cell structure prepared in Comparative Example 1.

[0035] Fig.12 Shown is the cell structure prepared in Comparative Example 2.

[0036] Fig.13 Shown is the battery cell structure prepared in Comparative Example 3. DETAILED DESCRIPTION

[0037] The present invention discloses a tab-free battery cell and a preparation method thereof and a solid-state battery. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0038] In the description of the present invention, a list of items connected by the term "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.

[0039] 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.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0042] 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.

[0043] In order to solve the problem that in the prior art, due to the sudden change in thickness during the pressing process of all-solid-state batteries, the shear force at the tab is large, which easily causes the tab to break, the present invention adopts the following technical solution:

[0044] A first aspect of the present invention provides a tab-free battery cell, wherein the tab-free battery cell comprises a tab-free battery cell unit, wherein the tab-free battery cell unit comprises a stacked tab-free battery cell assembly and a conductive buffer sheet;

[0045] Wherein, the tab-free battery core assembly comprises a first current collector, a positive electrode sheet, an electrolyte sheet, a negative electrode sheet, and a second current collector stacked in sequence; the first current collector and the second current collector are tab-free current collectors;

[0046] The conductive buffer sheet comprises a conductor and a buffer area; the buffer area comprises a first insulating material; the conductor comprises an internal conductor and an external conductor; the external conductor at least partially extends to the outside of the edge of the conductive buffer sheet;

[0047] The conductor is a sheet structure, and the buffer area surrounds the built-in conductor; and / or the conductor is a mesh structure, and the first insulating material is filled in at least part of the pores of the mesh structure.

[0048] The tab-free battery cell unit of the present invention comprises stacked tab-free battery cell assemblies and conductive buffer sheets. During the battery cell pressing process, there is no need to consider the influence of edge shear force on the tabs. When the tab-free battery cell units are stacked into solid-state batteries in the later stage, the battery design is more flexible.

[0049] The conductive buffer sheet in the present invention can reduce the volume expansion and contraction of the tab-free battery cell during charging and discharging, and can also guide current into and out of the battery cell. The specific shape of the conductor in the conductive buffer sheet in the present invention is not particularly limited and can be selected as needed, such as Figure 3 , Figure 4 and Figure 5 As shown, the built-in conductor in the conductor can be rectangular or elliptical. The conductive buffer sheet in the present invention mainly has two forms. The first conductor adopts a solid sheet structure, and the buffer area surrounds the built-in conductor. Figure 3 and Figure 4 As shown; the second conductor is a mesh structure, and the first insulating material is filled in at least part of the pores of the mesh structure.

[0050] The tab-free battery cell assembly of the present invention comprises at least two current collectors, a positive electrode sheet, an electrolyte sheet and a negative electrode sheet. The positive electrode sheet and the negative electrode sheet need to be spaced apart by the electrolyte sheet. The tab-free battery cell assembly and the conductive buffer sheet are stacked in such a way that the conductive buffer sheet is stacked on the outermost current collector surface.

[0051] In one embodiment, the tab-free battery cell assembly may include a first current collector, a positive electrode sheet, an electrolyte sheet, a negative electrode sheet, and a second current collector stacked in sequence. In this embodiment, the tab-free battery cell assembly and the conductive buffer sheet may be stacked in such a manner that the conductive buffer sheet is stacked on the surface of the first current collector on the side away from the positive electrode sheet, and / or the conductive buffer sheet is stacked on the surface of the second current collector on the side away from the negative electrode sheet.

[0052] In one embodiment, the tab-free battery cell assembly may include a first current collector, a first positive electrode sheet, a first electrolyte sheet, a first negative electrode sheet, a second current collector, a second positive electrode sheet, a second electrolyte sheet, a second negative electrode sheet, and a third current collector stacked in sequence. In this embodiment, the tab-free battery cell assembly and the conductive buffer sheet may be stacked in such a manner that the conductive buffer sheet is stacked on the surface of the first current collector on the side away from the first positive electrode sheet, and / or the conductive buffer sheet is stacked on the surface of the third current collector on the side away from the second negative electrode sheet.

[0053] According to the present invention, the internal conductor and the external conductor are integrally formed. Exemplarily, the conductor is a foil conductor and / or a mesh conductor; optionally, the conductor is made of at least one of stainless steel, copper, aluminum, nickel and carbon.

[0054] According to the present invention, the specific surface area of ​​the buffer region may be 0 to 99% of the total specific surface area of ​​the conductive buffer sheet; preferably, the specific surface area of ​​the buffer region may be 30 to 95% of the total specific surface area of ​​the conductive buffer sheet. Exemplarily, the first insulating material may be selected from at least one of silica gel, polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride.

[0055] A preferred embodiment of the present invention is as follows Figure 6 As shown, the positive electrode sheet may include a positive electrode active material region and a positive electrode stress dispersion region, wherein the positive electrode active material region is located in the central region of the positive electrode sheet, and the positive electrode stress dispersion region surrounds the positive electrode active material region; optionally, the specific surface area of ​​the positive electrode stress dispersion region may be 0 to 30% of the total specific surface area of ​​the positive electrode sheet, preferably, the specific surface area of ​​the positive electrode stress dispersion region may be 0.1 to 10% of the total specific surface area of ​​the positive electrode sheet.

[0056] Exemplarily, the positive electrode stress dispersion region includes a second insulating material; the second insulating material includes an inorganic material and / or an organic material, the organic material is selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material is selected from Al 2 O 3 , AlN, γ-AlOOH, an oxide solid electrolyte, a halide solid electrolyte and a sulfide solid electrolyte.

[0057] In this embodiment, the compacted thickness of the positive electrode active material region is close to the compacted thickness of the positive electrode stress dispersion region. Exemplarily, the difference between the compacted thickness of the positive electrode active material region and the compacted thickness of the positive electrode stress dispersion region is no more than 50 μm.

[0058] The positive electrode active material region in the present invention includes a composite positive electrode material, which is composed of a positive electrode active material, an electrolyte material, a conductive agent, and a binder. The positive electrode active material includes LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 、LiNi x Co y Mn z O 2 (NCM; x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1), LiNi x Co y Al z O 2(NCA; x+y+z=1; 0≤x<1, 0≤y<1, 0≤z<1), xLi 2 MnO 3 (1-x)LiTMO 2 (TM = one or more of Ni, Mn, Co, 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) or one or more thereof. In the present invention, the electrolyte material, the conductive agent and the binder in the composite positive electrode material are not particularly limited and can be selected by conventional techniques.

[0059] A preferred embodiment of the present invention is as follows Figure 7 As shown, the negative electrode sheet may include a negative electrode active material region and a negative electrode stress dispersion region, wherein the negative electrode active material region is located in the central region of the negative electrode sheet, and the negative electrode stress dispersion region surrounds the negative electrode active material region; optionally, the specific surface area of ​​the negative electrode stress dispersion region may be 0 to 30% of the total specific surface area of ​​the negative electrode sheet, preferably, the specific surface area of ​​the negative electrode stress dispersion region may be 0.1 to 10% of the total specific surface area of ​​the negative electrode sheet.

[0060] Exemplarily, the negative electrode stress dispersion region may include a third insulating material; the third insulating material may include an inorganic material and / or an organic material, the organic material may be selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material may be selected from Al 2 O 3, AlN, γ-AlOOH, an oxide solid electrolyte, a halide solid electrolyte and a sulfide solid electrolyte.

[0061] The negative electrode active material region in the present invention includes a composite negative electrode material, and the composite negative electrode material is composed of a negative electrode active material, an electrolyte material, a conductive agent, and a binder. The negative electrode active material includes lithium titanate, metal Li, In, Sn and their respective alloys, graphite, hard carbon, soft carbon, mesophase carbon microspheres, carbon-based active materials of highly oriented pyrolytic graphite, and one or more Si-based active materials of Si elemental, Si alloy, silicon oxide, and silicon carbon. In the present invention, there is no special limitation on the electrolyte material, conductive agent, and binder in the composite negative electrode material, and they can also be selected by conventional technology.

[0062] According to the present invention, the first current collector and the second current collector can be independently selected from foil current collectors and / or mesh current collectors, and the materials of the first current collector and the second current collector can be independently selected from at least one of stainless steel, copper, aluminum, nickel and carbon. Exemplarily, the materials of the first current collector and the second current collector can be copper-aluminum composite foil.

[0063] In the present invention, the electrolyte sheet is not particularly limited. In one embodiment of the present invention, the electrolyte sheet includes an electrolyte material and a binder. Exemplarily, the electrolyte material is 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 S 5 )(70≤x≤80, 0≤y≤30, 0≤z≤30) or a combination of at least two thereof; the binder is one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), nitrile rubber (NBR), styrene-butadiene latex (SBR), and carboxymethyl cellulose (CMC); the conductive agent is one or more of conductive carbon black, carbon nanotubes (CNTs), carbon nanofibers (CNFs), and vapor grown carbon fibers (VGCFs).

[0064] A second aspect of the present invention provides a method for preparing a tab-free battery cell, the method comprising the following steps:

[0065] S1, stacking and pressing the first current collector, the positive electrode sheet, the electrolyte sheet, the negative electrode sheet and the second current collector to obtain a tab-free battery cell assembly;

[0066] S2, assembling the conductor and the buffer material to obtain a conductive buffer sheet;

[0067] S3, stacking the conductive buffer sheet and the tab-free battery cell assembly to obtain a tab-free battery cell unit.

[0068] In the present invention, the non-polar ear current collector is first stacked with the positive electrode sheet, the electrolyte sheet, and the negative electrode sheet, and then pressed and densified to obtain a non-polar ear battery cell assembly, which avoids the problem of large shear force at the pole ear, which easily causes the pole ear to break. Then the conductive buffer sheet and the non-polar ear battery cell assembly are stacked to obtain a non-polar ear battery cell unit. The whole process does not need to consider the influence of edge shear force on the pole ear, and the stacking form of the non-polar ear battery cell assembly and the non-polar ear battery cell unit is more flexible and can adapt to the design of various solid-state batteries.

[0069] The tab-free battery core assembly and the conductive buffer sheet involved in the present invention are stacked in a manner that the conductive buffer sheet is stacked on the outermost current collector surface.

[0070] According to the present invention, the compaction densification may include at least one of isostatic pressing, flat plate pressing and roller pressing. Exemplarily, the conditions of isostatic pressing may include: pressing temperature of 25-300°C, pressure of 150-600MPa, and time of 5-40min; the conditions of flat plate pressing may include: pressing temperature of 25-300°C, pressure of 150-600MPa, and time of 5-40min; the roller line pressure in roller pressing may be 1-20t / cm.

[0071] In the present invention, there is no particular limitation on the preparation methods of the positive electrode sheet, the electrolyte sheet and the negative electrode sheet, and they can be selected from conventional techniques. As an example, the positive electrode sheet can be obtained by dry rolling or wet coating of the positive electrode mixture and then die cutting, the negative electrode sheet can be obtained by dry rolling or wet coating of the negative electrode mixture and then die cutting, and the electrolyte sheet can be obtained by dry rolling of the electrolyte mixture or wet coating with a PET film or foil, wherein the electrolyte sheet prepared by wet coating needs to be transferred to the negative electrode sheet or the positive electrode sheet.

[0072] According to the present invention, the method for preparing the tab-free battery cell may further include: stacking a plurality of the tab-free battery cell units to obtain a tab-free battery cell.

[0073] In an embodiment of the present invention, the stacked tab-free battery cells may be subjected to isostatic pressing or flat pressing. For example, the pressure is 10 to 300 MPa and the temperature is 25 to 200°C.

[0074] A third aspect of the present invention provides a solid-state battery, comprising a battery cell, wherein the battery cell is the above-mentioned tab-free battery cell and / or the tab-free battery cell prepared according to the above-mentioned preparation method.

[0075] like Figure 1 and Figure 2 As shown, the solid-state battery of the present invention is stacked in the order of a conductive buffer sheet, a tab-free battery cell unit, a conductive buffer sheet, a tab-free battery cell unit, and a conductive buffer sheet.

[0076] The present invention is further described in detail by way of examples. The raw materials used in the examples can be obtained through commercial sources.

[0077] Example 1

[0078] The preparation method of the tab-free battery cell and the all-solid-state battery comprises the following steps:

[0079] (1) The positive electrode active material (NCM), sulfide electrolyte (Li 6 PS 5Cl), a conductive agent (vapor-grown carbon fiber) and a binder (polytetrafluoroethylene) are mixed in a mass ratio of 80:16.5:3:0.5 to obtain a positive electrode mixture. The positive electrode mixture is roll-pressed and die-cut to obtain a positive electrode sheet.

[0080] (2) The negative electrode active material (graphite), sulfide electrolyte (Li 6 PS 5 Cl), a conductive agent (vapor-grown carbon fiber), and a binder (polytetrafluoroethylene) are mixed in a mass ratio of 70:26.5:3:0.5 to obtain a negative electrode mixture. The negative electrode mixture is roll-pressed and die-cut to obtain a negative electrode sheet.

[0081] (3) Die-cut the stainless steel foil into a current collector.

[0082] (4) Sulfide electrolyte (Li 6 PS 5 Cl) and binder (polytetrafluoroethylene) are mixed in a mass ratio of 99.5:0.5 to obtain an electrolyte mixture, and the electrolyte mixture is rolled and die-cut to obtain an electrolyte sheet. A stress dispersion area is set around the positive electrode sheet and the negative electrode sheet, and the stress dispersion area surrounds the positive electrode active material area and the negative electrode active material area. The stress dispersion area is filled with polyamide resin. This eliminates the problem of edge stress concentration and brittle cracking during stacking and pressing due to different surface areas of the positive electrode sheet, the negative electrode sheet and the electrolyte sheet.

[0083] (5) The tab-free battery cell assembly is stacked in the order of current collector 1, positive electrode sheet, electrolyte sheet, negative electrode sheet, current collector 2, positive electrode sheet, electrolyte sheet, negative electrode sheet, and current collector 3. Among them, current collector 1, current collector 2, and current collector 3 all have no tabs.

[0084] (6) isostatically pressing the tab-free battery cell assembly at a pressure of 500 MPa, a time of 10 min, and a temperature of 70° C.

[0085] (7) The conductor and the buffer area material are assembled to obtain a conductive buffer sheet, wherein the conductor includes an internal conductor and an external conductor, the buffer area material surrounds the internal conductor, and the external conductor portion extends to the outside of the edge of the conductive buffer sheet; the buffer area material of conductive buffer sheet 1 and conductive buffer sheet 3 is silicone and the conductor is aluminum, and the buffer area material of conductive buffer sheet 2 is silicone and the conductor is copper.

[0086] (8) The conductive buffer sheet 1, the tab-free battery cell assembly, the conductive buffer sheet 2, the tab-free battery cell assembly, and the conductive buffer sheet 3 are stacked in order to obtain a tab-free battery cell unit. The same conductive buffer sheet can only contact the positive electrode or the negative electrode side of the tab-free battery cell unit. The specific structure of the battery cell is as follows: Figure 8 After stacking, flat plate pressing is performed at a pressure of 10 MPa and a temperature of 60°C.

[0087] (9) After the second external conductors are welded on both sides of the battery cell, an aluminum-plastic film is packaged on the outside to obtain an all-solid-state battery.

[0088] Example 2

[0089] The preparation method of the tab-free battery cell and the all-solid-state battery in this embodiment is generally the same as that in Embodiment 1, except that:

[0090] The tab-free battery cell is stacked in the order of conductive buffer sheet 1, tab-free battery cell unit, conductive buffer sheet 2, tab-free battery cell unit, conductive buffer sheet 3, tab-free battery cell unit, and conductive buffer sheet 4. The buffer area material of conductive buffer sheet 1 and conductive buffer sheet 3 is silicone and the conductor is aluminum. The buffer area material of conductive buffer sheet 2 and conductive buffer sheet 4 is silicone and the conductor is copper. The specific structure of the battery cell is as follows: Fig. 9 shown.

[0091] Example 3

[0092] The preparation method of the tab-free battery cell and the all-solid-state battery in this embodiment is generally the same as that in Embodiment 1, except that:

[0093] The cells are stacked in the order of current collector 1, positive electrode sheet, electrolyte sheet, negative electrode sheet, current collector 2, positive electrode sheet, electrolyte sheet, negative electrode sheet, current collector 3, positive electrode sheet, electrolyte sheet, negative electrode sheet and current collector 4 to form a tab-free cell unit. Current collector 1, current collector 2, current collector 3 and current collector 4 all have tabs. The specific structure of the cell is as follows: Fig.10 shown.

[0094] Example 4

[0095] The preparation method of the tab-free battery cell and the all-solid-state battery in this embodiment is the same as that in Embodiment 3, except that:

[0096] In this embodiment, no stress dispersion area is provided around the positive electrode sheet and the negative electrode sheet.

[0097] Comparative Example 1

[0098] The preparation method of the tab-free battery cell and the all-solid-state battery in this comparative example is the same as that in Example 1, except that:

[0099] In this comparative example, the current collectors 1 and 3 in the tab-free battery cell assembly have tabs.

[0100] In this comparative example, a silicone pad is used to replace the conductive buffer sheet in the tab-free battery cell.

[0101] The specific structure of the battery cell is as follows Fig.11 shown.

[0102] Comparative Example 2

[0103] The preparation method of the tab-free battery cell and the all-solid-state battery in this comparative example is the same as that in Example 2, except that:

[0104] In this comparative example, the current collectors 1 and 3 in the tab-free battery cell assembly have tabs.

[0105] In this comparative example, a silicone pad is used to replace the conductive buffer sheet in the tab-free battery cell.

[0106] The specific structure of the battery cell is as follows Fig.12 shown.

[0107] Comparative Example 3

[0108] The preparation method of the tab-free battery cell and the all-solid-state battery in this comparative example is the same as that in Example 3, except that:

[0109] In this comparative example, the current collector 1 and the current collector 4 in the tab-free battery cell assembly have tabs.

[0110] In this comparative example, a silicone pad is used to replace the conductive buffer sheet in the tab-free battery cell.

[0111] The specific structure of the battery cell is as follows Fig.13 shown.

[0112] Test Example 1

[0113] The solid-state batteries prepared in the above-mentioned embodiments and comparative examples were subjected to performance tests, specifically including:

[0114] The all-solid-state battery is pressurized to 10MPa in the test fixture and the battery performance test is carried out in a 60°C environment. Observe whether the battery has a short circuit or an open circuit, and test the first cycle charge and discharge performance of the battery at 0.1C. Ten batteries are made for each embodiment or comparative example. The success rate is calculated by dividing the number of batteries without short circuit or open circuit by 10 and multiplying by 100%, and the battery discharge specific capacity is the average discharge specific capacity of batteries without short circuit or open circuit.

[0115] The test results are shown in Table 1.

[0116] Table 1

[0117] Battery preparation success rate Battery discharge capacity Example 1 100％ 183mAh / g Example 2 100％ 177mAh / g Example 3 100％ 168mAh / g Example 4 70％ 164mAh / g Comparative Example 1 80％ 178mAh / g Comparative Example 2 50％ 170mAh / g Comparative Example 3 50％ 157mAh / g

[0118] It can be seen from the data in Table 1 that, compared with Comparative Examples 1 to 3, the solid-state batteries prepared by the methods of Examples 1 to 4 of the present invention improve the success rate of solid-state battery preparation and have good electrochemical properties. The methods of the embodiments of the present invention avoid the problem of easy breakage of the tabs during the densification of the battery cells, and the battery cell design is more flexible, thereby improving the production efficiency of solid-state batteries.

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A tab-free battery cell, characterized in that: The anode-free battery cell includes a cathode-free battery cell unit, and the cathode-free battery cell unit includes a stacked cathode-free battery cell assembly and a conductive buffer sheet; Wherein, the tab-free battery core assembly comprises a first current collector, a positive electrode sheet, an electrolyte sheet, a negative electrode sheet, and a second current collector stacked in sequence; the first current collector and the second current collector are tab-free current collectors; The conductive buffer sheet comprises a conductor and a buffer area; the buffer area comprises a first insulating material; the conductor comprises an internal conductor and an external conductor; the external conductor at least partially extends to the outside of the edge of the conductive buffer sheet; The conductor is a sheet structure, and the buffer area surrounds the built-in conductor; and / or the conductor is a mesh structure, and the first insulating material is filled in at least part of the pores of the mesh structure.

2. The tab-free battery cell according to claim 1, characterized in that: The internal conductor and the external conductor are integrally formed; the conductor is a foil-shaped conductor and / or a mesh-shaped conductor; Optionally, the material of the conductor is selected from at least one of stainless steel, copper, aluminum, nickel and carbon.

3. The tab-free battery cell according to claim 1, characterized in that: The specific surface area of ​​the buffer region is 0 to 99% of the total specific surface area of ​​the conductive buffer sheet; preferably, the specific surface area of ​​the buffer region is 30 to 95% of the total specific surface area of ​​the conductive buffer sheet; Optionally, the first insulating material is selected from at least one of silica gel, polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride.

4. The tab-free battery cell according to claim 1, characterized in that: The positive electrode sheet comprises a positive electrode active material region and a positive electrode stress dispersion region, wherein the positive electrode active material region is located in the central region of the positive electrode sheet, and the positive electrode stress dispersion region surrounds the positive electrode active material region; Optionally, the specific surface area of ​​the positive electrode stress dispersion region is 0-30% of the total specific surface area of ​​the positive electrode sheet. Preferably, the specific surface area of ​​the positive electrode stress dispersion region is 0.1-10% of the total specific surface area of ​​the positive electrode sheet. Optionally, the positive electrode stress dispersion region includes a second insulating material; the second insulating material includes an inorganic material and / or an organic material, the organic material is selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material is selected from at least one of Al2O3, AlN, γ-AlOOH, oxide solid electrolyte, halide solid electrolyte and sulfide solid electrolyte.

5. The tab-free battery cell according to claim 1, characterized in that: The negative electrode sheet comprises a negative electrode active material region and a negative electrode stress dispersion region, wherein the negative electrode active material region is located in the central region of the negative electrode sheet, and the negative electrode stress dispersion region surrounds the negative electrode active material region; Optionally, the specific surface area of ​​the negative electrode stress dispersion region is 0-30% of the total specific surface area of ​​the negative electrode sheet. Preferably, the specific surface area of ​​the negative electrode stress dispersion region is 0.1-10% of the total specific surface area of ​​the negative electrode sheet. Optionally, the negative electrode stress dispersion region includes a third insulating material; the third insulating material includes an inorganic material and / or an organic material, the organic material is selected from at least one of polypropylene, polyethylene, polyethylene terephthalate, polyamide resin, polytetrafluoroethylene and polyvinyl chloride, and the inorganic material is selected from at least one of Al2O3, AlN, γ-AlOOH, an oxide solid electrolyte, a halide solid electrolyte and a sulfide solid electrolyte.

6. The tab-free battery cell according to claim 1, characterized in that: The first current collector and the second current collector are independently selected from foil current collectors and / or mesh current collectors, and the materials of the first current collector and the second current collector are independently selected from at least one of stainless steel, copper, aluminum, nickel and carbon.

7. A method for preparing a tab-free battery cell according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1, stacking and pressing the first current collector, the positive electrode sheet, the electrolyte sheet, the negative electrode sheet and the second current collector to obtain a tab-free battery cell assembly; S2, assembling the conductor and the buffer material to obtain a conductive buffer sheet; S3, stacking the conductive buffer sheet and the tab-free battery cell assembly to obtain a tab-free battery cell unit.

8. The preparation method according to claim 7, characterized in that: The compaction densification comprises at least one of isostatic pressing, plate pressing and roller pressing.

9. The preparation method according to claim 7, characterized in that: The method for preparing the tab-free battery cell also includes: stacking a plurality of tab-free battery cell units to obtain a tab-free battery cell.

10. A solid-state battery, characterized in that: The solid-state battery comprises a battery cell, and the battery cell is the tab-free battery cell according to any one of claims 1 to 6 and / or the tab-free battery cell prepared according to the preparation method according to any one of claims 7 to 9.

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