Secondary battery and method for manufacturing the same

Abstract

The invention provides a secondary battery and a preparation method thereof, the secondary battery comprises a first pole piece, a second pole piece and an insulation support part, the first pole piece and the second pole piece are alternately laminated along a first direction to form a laminated body, the first pole piece is provided with an extension part which extends outwards compared with the second pole piece, and the insulation support part is arranged on the extension part. A gap part is formed between the adjacent extending parts in the first direction, the insulating supporting part comprises a filling part and a covering part, the filling part fills the gap part, and the covering part covers the end parts of the extending parts. The safety of the secondary battery provided by the invention is high.

Description

Technical Field

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

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. Secondary batteries have made great progress, but current secondary batteries still have safety risks.

[0003] Therefore, how to improve the safety performance of secondary batteries has become an urgent problem to be solved in this field. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its object is to provide a secondary battery with high safety and a method for manufacturing the same.

[0005] A first aspect of the present application provides a secondary battery, characterized in that it includes a first pole sheet, a second pole sheet and an insulating support portion, the first pole sheet and the second pole sheet are alternately stacked along a first direction to form a stack, the first pole sheet has an extension portion extending outward compared to the second pole sheet, a gap portion is formed between the adjacent extension portions in the first direction, and the insulating support portion includes a filling portion and a covering portion, the filling portion fills the gap portion, and the covering portion covers the end portion of the extension portion.

[0006] Therefore, the present application greatly strengthens the structural stability by providing insulating support portions in the protruding portions and gap portions in the pole piece stack, thereby improving the safety of the battery.

[0007] In any embodiment, the filling part is connected to the covering part and fills the gap. Optionally, the filling part fills the end of the second pole piece located in the gap. By making the filling part fully fill the gap, the structure is more stable and the battery safety is improved.

[0008] In any embodiment, the height of the filling part in the first direction is equal to the height of the gap in the first direction. By making the filling part fully fill the gap, the structure is made more stable and the battery safety is improved.

[0009] In any embodiment, the covering part and the filling part are integrally formed, so that the insulating support body is firmly arranged on the extension part and the gap part as a whole, the structural stability is stronger, and the battery safety is improved.

[0010] In any embodiment, the covering portion covers the entire stack along the first direction. Thus, the insulating support body itself has a stronger pressure resistance, which enhances the stability of the battery stack structure and improves battery safety.

[0011] In any embodiment, an insulating support portion is formed outside the stack and around the entire circumference of the stack, thereby further improving the structural stability of the entire battery stack.

[0012] In any embodiment, the secondary battery includes N+1 layers of the first pole sheet and N layers of the second pole sheet (N≥1), and a solid electrolyte membrane is arranged between the first pole sheet and the second pole sheet stacked adjacent to each other in a first direction, the first pole sheet is a negative pole sheet, and the second pole sheet is a positive pole sheet.

[0013] By providing an insulating support portion in a solid-state battery stack, the safety of the solid-state battery is improved.

[0014] In any embodiment, the laminated body formed with the insulating support portion is subjected to a compression treatment, wherein the compression treatment is: pressurizing each surface of the laminated body formed with the insulating support portion under a pressure greater than 0 MPa and less than or equal to 1000 MPa, optionally under a pressure of 50 MPa to 1000 MPa, and optionally, isostatic pressing is performed on the laminated body formed with the insulating support portion. Thus, the solid-state battery can have high volume energy density while having excellent safety.

[0015] In any embodiment, the material of the insulating support portion includes a polymer, and optionally, the glass transition temperature of the polymer is -30°C to 200°C. The polymer has the characteristics of insulation and curability, and can be easily filled in the gap and cover the end of the extension by controlling the conditions, thereby achieving the effect of insulation and supporting the structure.

[0016] The second aspect of the present application also provides a method for preparing a secondary battery, which comprises the following steps:

[0017] A stacking step: alternately stacking a first pole piece and a second pole piece along a first direction to form a stacked body, wherein the first pole piece is formed with an extension portion extending outward compared to the second pole piece, and a gap portion is formed between adjacent extension portions in the first direction; and

[0018] Filling step: Filling the gap and the end of the extension portion with a slurry containing a high molecular polymer to form an insulating support portion.

[0019] Through the above preparation method, a secondary battery with strong structural stability and high safety can be obtained.

[0020] In any embodiment, before the stacking step, a negative electrode film layer is disposed on at least one surface of the negative electrode current collector to form the first pole piece, a positive electrode film layer is disposed on at least one surface of the positive electrode current collector to form the second pole piece, and a solid electrolyte is coated on the surface of the first pole piece or the second pole piece to form a solid electrolyte membrane. Thus, a solid-state battery with strong structural stability and high safety can be obtained.

[0021] In any embodiment, in the filling step, the slurry is filled by dipping, coating or injecting. The insulating support portion can be formed by the above filling method.

[0022] In any embodiment, after the filling step, a compression step is further included: pressurizing each surface of the laminate formed with the insulating support portion at a pressure greater than 0 MPa and less than or equal to 1000 MPa, optionally at a pressure of 50 MPa to 1000 MPa, and optionally, isostatic pressing is performed on the laminate formed with the insulating support portion. Through this step, the prepared solid-state battery can have excellent safety while greatly improving the volume energy density.

[0023] A third aspect of the present application provides an electrical device, characterized in that it includes the above-mentioned secondary battery, or a secondary battery obtained by the above-mentioned preparation method.

[0024] Effects of the Invention

[0025] According to the present application, a secondary battery with high structural stability and excellent safety can be provided. Furthermore, according to the present invention, a solid-state battery with high safety and high volume energy density can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a partial schematic cross-sectional view of a secondary battery according to one embodiment of the present application.

[0027] Figure 2 This is a schematic cross-sectional view of a secondary battery according to one embodiment of the present application.

[0028] Figure 3 This is a schematic cross-sectional view of a secondary battery according to one embodiment of the present application.

[0029] Figure 4 This is a CT photo of the solid-state battery of Example 1 of the present application.

[0030] Figure 5 This is a disassembly photo of the solid-state battery of Comparative Example 1 of this application.

[0031] Description of reference numerals:

[0032] 1 first pole piece; 11 extension portion; 111 end portion of the extension portion; 2 second pole piece; 3 insulating support portion; 31 filling portion; 32 covering portion; 1' negative electrode; 1'a negative electrode current collector; 1'b negative electrode film layer; 2' positive electrode; 2'a positive electrode current collector; 2'b positive electrode film layer; 3' insulating support portion. DETAILED DESCRIPTION

[0033] Below, the embodiments of the secondary battery and the method for preparing the same of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0034] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0035] 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.

[0036] At present, existing secondary batteries have a multi-layer electrode sheet stacking structure formed by alternating stacking of first electrode sheets and second electrode sheets, and overhang portions are formed at the ends of adjacent first electrode sheets in a direction perpendicular to the stacking direction (that is, the first electrode sheet extends outward relative to the second electrode sheet adjacent to it in the stacking direction, thereby forming a gap between adjacent extended portions). This causes the extended electrode sheets to be squeezed and broken when the secondary battery is subjected to external forces such as impact or external pressure, exposing the internal metal and causing an internal short circuit, greatly reducing the safety of the battery and even causing battery failure. In particular, this phenomenon often occurs during the battery preparation process, which also makes the battery manufacturability poor.

[0037] In view of the above, the first aspect of the present application provides a secondary battery, such as Figure 1 As shown, the secondary battery includes a first pole piece 1, a second pole piece 2 and an insulating support portion 3, the first pole piece 1 and the second pole piece 2 are alternately stacked along a first direction, the first pole piece 1 has an extension portion 11 extending outward compared to the second pole piece 2, a gap portion is formed between the adjacent extension portions 11 in the first direction, the insulating support portion 3 includes a filling portion 31 and a covering portion 32, the filling portion 31 fills the gap portion, and the covering portion 32 covers the end portion 111 of the extension portion.

[0038] Here, the so-called “first direction” refers to the stacking direction of the pole pieces, and the so-called “outer side” refers to the outer side relative to the middle of the pole pieces.

[0039] The length of the protruding portion 11 (ie, the length of the first pole piece 1 protruding outward compared with the second pole piece 2 ) is less than 100 mm, and can be optionally 0.5 mm-10 mm, or optionally 1 mm-6 mm.

[0040] In the above-mentioned secondary battery, an insulating support portion 3 is provided on the overhang portion (the above-mentioned protruding portion and the gap portion), thereby filling the gap portion to reinforce the structure of the protruding portion 11 of the pole piece, thereby preventing the protruding portion 11 of the pole piece from being conductive due to breaking (for example, when the first pole piece 1 is a negative electrode, the pole piece breaks and copper is exposed), and at the same time, the end portion 111 of the protruding portion is covered to prevent the end portion 111 from exposing metal and causing a short circuit. The structural stability is improved, and the safety of the battery is excellent.

[0041] In some embodiments, the filling portion 31 is connected to the covering portion 32 and fills the gap. Optionally, the filling portion 31 fills the gap to the end of the second pole piece 2 located in the gap. The length of the filling portion 31 in the second direction is equal to the length of the extension 11. Here, the so-called "second direction" refers to the direction perpendicular to the first direction. In some embodiments, the height of the filling portion 31 in the first direction is equal to the height of the gap in the first direction. Thus, the filling portion 31 fully fills the gap, further reducing the risk of the extension breaking due to the presence of the gap, making the structure more stable and improving the battery safety.

[0042] In some embodiments, the covering portion 32 is integrally formed with the filling portion 31 , so that the insulating support body 3 is firmly disposed on the extension portion 11 and the gap portion as a whole, and the structural stability is enhanced, thereby improving the battery safety.

[0043] In some embodiments, the covering portion 32 covers the entire stack along the first direction. Optionally, the height of the covering portion 32 in the first direction is equal to the stacking thickness of the stack in the first direction. Optionally, the length of the covering portion 32 in the second direction is greater than 0 mm and less than or equal to 10 mm, and is optionally 0.5 mm to 6 mm. As a result, the insulating support body itself has a stronger pressure resistance, which enhances the stability of the battery stack structure.

[0044] In some embodiments, an insulating support portion is formed on the outside of the above-mentioned stack and around the entire circumference of the stack. For example, the pole pieces constituting the stack can be quadrilateral, circular, etc., and the insulating support portion can be formed on the four sides of the stack that is a rectangular parallelepiped or the entire circumference of the stack that is a cylinder, that is, the insulating support portion is formed on the entire side of the stack except for the upper and lower sides in the stacking direction. Thereby, the structural stability of the entire battery stack is further improved.

[0045] In some embodiments, as long as the material forming the above-mentioned insulating support portion (covering portion + filling portion) is insulating and can play a structural support role, a material that can be cured under certain conditions can be used, for example, a material including a polymer can be used, and the glass transition temperature of the above-mentioned polymer is preferably -30°C to 200°C, and more preferably 80°C to 120°C. As a polymer, for example, polyolefins such as polypropylene and polyethylene, polystyrene (PS), ethylene acetate-ethylene copolymer, epoxy resin, silicone rubber, and polyurethane, polyacrylic acid, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT) resin, epoxy resin, etc. can be used, and one or more mixtures can be used. As a slurry containing a polymer, hot melt adhesive, Kraft AB adhesive, glass prepreg, etc. are preferably used.

[0046] When hot melt adhesive is used, the insulating support portion is a structure formed by curing the hot melt adhesive, which has a certain viscosity and hardness, and can fill the gap and cover the end of the extension. At the same time, the hot melt adhesive also has a certain hardness, which can enhance the structural strength and improve the bending resistance. The hot melt adhesive used in this application can be a conventional hot melt adhesive, such as polyethylene hot melt adhesive, polypropylene hot melt adhesive, ethylene and its copolymer hot melt adhesive, polyester hot melt adhesive, polyamide hot melt adhesive, and of course, it can also be a specially configured hot melt adhesive, which is not specifically limited in the embodiments of this application.

[0047] In addition, for existing solid-state batteries, during the preparation process, it is difficult for the solid electrolyte to fit tightly with the pole piece under normal pressure (1-40Mpa) during hot pressing, and its compactness cannot be achieved, resulting in a large overall resistance and low energy density of the battery. In order to improve the energy density, it is necessary to perform six-sided pressurization at a pressure greater than 0Mpa and less than or equal to 1000Mpa, especially at a pressure of 50-1000Mpa, after hot pressing. However, due to the presence of an overhang portion in the battery, the structural stability is poor, resulting in the negative electrode extending outward compared to the positive electrode during the six-sided pressurization process, especially when the side of the stack (except the upper and lower surfaces in the stacking direction) is hot pressed, which easily breaks and exposes copper, causing the battery cell to short-circuit, making it difficult to prepare into a battery, and the battery is poorly manufacturable.

[0048] In view of this, in some embodiments, according to the stacking method of first electrode sheet (negative electrode sheet) / solid electrolyte membrane / second electrode sheet (positive electrode sheet) / solid electrolyte membrane / first electrode sheet / solid electrolyte membrane...first electrode sheet (negative electrode sheet), a solid electrolyte membrane is arranged between the adjacent first electrode sheets (negative electrode sheets) and the second electrode sheets (positive electrode sheets) stacked in the first direction, so as to form a stacked body, which includes N+1 layers of negative electrode sheets and N layers of positive electrode sheets, where N≥1.

[0049] The solid-state battery of the present application is provided with an insulating support part, which effectively solves the problem of the negative electrode extension part breaking and exposing copper, improves the stability of the battery structure, avoids the risk of internal short circuit of the battery, improves the safety of the battery, and improves the manufacturability of the battery, which has a huge promoting effect on the mass production of solid-state batteries.

[0050] In some embodiments, the above-mentioned stack formed with the insulating support part of the solid-state battery is subjected to a compression treatment, and the compression treatment is: pressurizing each surface of the stack formed with the insulating support part under a pressure greater than 0 MPa and less than or equal to 1000 MPa, optionally under a pressure of 50 MPa to 1000 MPa, and optionally, performing isostatic pressing on the stack formed with the insulating support part.

[0051] The solid-state battery provided with an insulating support portion has a strong structural stability, and even after the above-mentioned compression treatment, the negative electrode extension portion will not break and expose the copper. Therefore, while the solid-state battery has excellent battery safety, the volume of the battery is reduced after the above-mentioned compression treatment, so that the volume energy density of the battery can be greatly improved.

[0052] The positive electrode plate may include a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector and including a positive electrode active material. The type of the positive electrode active material is not specifically limited and may be selected according to actual needs.

[0053] Optionally, the positive electrode active material may be selected from LiFe x1 Mn y1 M z1 PO4 (0≤x1≤1, 0≤y1≤1, 0≤z1≤1, x1+y1+z1=1, M is selected from one or more of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo), Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, LiNi 0.5-x2 Mn 1.5-y2 M′ x2+y2 O4 (-0.1≤x2≤0.5, 0≤y2≤1.5, M′ is selected from one or more of Mn, Co, Fe, Al, Mg, Ca, Ti, Mo, Cr, Cu, Zn), Li1+x2Ni 1－y2－z2Co y2 M″ z2 O2 (M″ is selected from one or more of Mn, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, -0.1≤x2≤0.2, 0≤y2≤1, 0≤z2≤1, 0≤y2+z2≤1) one or more. Further preferably, the above-mentioned positive electrode active material is selected from LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, Li3V3(PO4)3, LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiCoO2, LiNiO2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2、LiNi 0.8 Co 0.1 Al 0.1 O2、LiNi 0.8 Co 0.1 Mn 0.1 When the positive electrode active material is the lithium salt positive electrode active material, the corresponding negative electrode active material can be selected from one or more of graphite, soft carbon, hard carbon, silicon carbon, metallic lithium, and lithium alloy.

[0054] Optionally, the positive electrode active material may also be selected from one or more of V2O5, MnO2, TiS2, FeS2, SnS2, and CuS2. When the positive electrode active material is the non-lithium salt positive electrode active material, the corresponding negative electrode active material should be a negative electrode active material that can release lithium ions, such as metallic lithium or lithium alloy.

[0055] The positive electrode film layer may further include a conductive agent and a binder. There is no specific limitation on the types of the conductive agent and the binder, and they may be selected according to actual needs.

[0056] The negative electrode sheet may include a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector and including a negative electrode active material. The type of the negative electrode active material is not specifically limited and may be selected according to actual needs. For example, the negative electrode active material may be a Si-based material, a silicon-carbon material, a mixture of carbon and alloy elements, lithium metal, lithium alloy, graphite, hard carbon, etc.

[0057] The negative electrode film layer may further include a conductive agent and a binder. There is no specific limitation on the types of the conductive agent and the binder, and they may be selected according to actual needs.

[0058] The solid electrolyte in the solid electrolyte membrane can be any solid electrolyte commonly used in solid-state batteries, and its type is not particularly limited and can be selected according to actual needs. For example, the sulfide solid electrolyte described in CN111864256B can be used.

[0059] A second aspect of the present application provides a method for preparing a secondary battery, which comprises the following steps:

[0060] Lamination step: alternately laminating the first pole piece and the second pole piece along a first direction to form a laminate, wherein the first pole piece is formed with an extension portion extending outward compared with the second pole piece, and a gap portion is formed between the adjacent extension portions in the first direction, and

[0061] Filling step: Filling the gap and the end of the protruding portion with a slurry containing a high molecular polymer to form an insulating support portion.

[0062] Through the above preparation method, the problem of the negative electrode extension part breaking and exposing copper is effectively solved, the stability of the battery structure is improved, the risk of internal short circuit of the battery is avoided, and the battery safety is improved. At the same time, the battery manufacturability is improved, which has a huge promoting effect on the mass production of solid-state batteries.

[0063] In one embodiment, before the stacking step, a negative electrode film layer is disposed on at least one surface of the negative electrode current collector to form the first pole piece, a positive electrode film layer is disposed on at least one surface of the positive electrode current collector to form the second pole piece, and a solid electrolyte is coated on the surface of the first pole piece or the second pole piece to form a solid electrolyte membrane. Thus, a solid-state battery with strong structural stability and high safety can be obtained.

[0064] In one embodiment, in the filling step, there is no specific limitation on the filling method, as long as the slurry can be filled into the gap, for example, dipping, coating or injection can be used. As the injection method, for example, a method of high-pressure glue injection can be used after sealing the side of the secondary battery, thereby protecting the battery cell and preventing the negative electrode from exposing copper and overlapping the positive electrode. A method of injecting glue into the entire hard shell battery cell can also be used, thereby solving the problem of hard shell solid-state battery damage.

[0065] In one embodiment, after the filling step, a compression step is also included: at a pressure greater than 0 MPa and less than or equal to 1000 MPa, optionally at a pressure of 50 MPa to 1000 MPa, each surface of the laminate formed with the insulating support portion is pressurized, optionally, the laminate formed with the insulating support portion is subjected to isostatic pressing, and optionally, the laminate formed with the insulating support portion is subjected to warm isostatic pressing. There is no particular limitation on the pressure, temperature, and time of warm isostatic pressing, for example, it is above 100 MPa and below 2000 MPa, above 10°C and below 2000°C, and above 5 seconds and below 6000 seconds. Through this step, the volume of the battery is reduced, and the volume energy density of the prepared solid-state battery can be greatly improved.

[0066] The following is a detailed description of the preparation method of the secondary battery of the present application. The preparation method includes the following steps:

[0067] Pole preparation

[0068] In an environment with an ambient humidity of 0.03% to 0.05% and -60degc to -55degc, the above-mentioned negative electrode active materials (for example, silicon-based materials, MC materials (alloy / C materials), etc.), additives, conductive agents, binders and any other components are dispersed in a solvent (for example, deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on both surfaces of the negative electrode current collector to form a negative electrode film layer, and after drying, cold pressing and other processes, a negative electrode sheet is obtained. A solid electrolyte (for example, a sulfide solid electrolyte) is coated on the entire surface of the negative electrode film layer of the negative electrode sheet to form a solid electrolyte membrane. In addition, the above-mentioned positive electrode active materials, conductive agents, binders, lithium supplement agents and any other components are dispersed in a solvent (for example, N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on both surfaces of the positive electrode current collector to form a positive electrode film layer, and after drying, cold pressing and other processes, a positive electrode sheet is obtained.

[0069] Cascading

[0070] In an environment with an ambient humidity of 0.03% to 0.05% and -60 degrees Celsius to -55 degrees Celsius, the negative electrode sheet formed with the solid electrolyte membrane and the positive electrode sheet are alternately stacked in a first direction to form a stack of negative electrode sheet / solid electrolyte membrane / positive electrode sheet. The negative electrode protrudes outwardly compared to the positive electrode, and the protruding distance is greater than 2 mm, and a gap is formed between adjacent negative electrodes in the stacking direction.

[0071] In addition, the above-mentioned solid electrolyte (for example, a sulfide solid electrolyte) can also be coated on the entire surface of the positive electrode film layer of the positive electrode plate to form a solid electrolyte membrane, and then the positive electrode plate formed with the solid electrolyte membrane and the above-mentioned negative electrode plate are alternately stacked along the first direction to form the above-mentioned stacked body.

[0072] Hot Pressing

[0073] Next, hot pressing is performed in an environment with an ambient humidity of 0.03% to 0.05% and -60 degrees Celsius to -55 degrees Celsius, with hot pressing parameters of 6 MPa to 8 MPa, 85 to 95 degrees Celsius, and 20 seconds to 130 seconds. Thus, the solid-state battery maintains a relatively stable structure and avoids the misalignment of the pole piece caused by looseness.

[0074] filling

[0075] Next, in an environment with an ambient humidity of 0.03% to 0.05% and -60degc to -55degc, place it in a glue injection mold, the single side of which is 1mm to 10mm larger than the outer contour of the battery cell. After sealing, inject hot melt adhesive (containing polyolefins, such as polypropylene or a mixture of polypropylene and other polymers) with an injection pressure of 0.3Mpa to 0.6Mpa, a temperature of 150℃ to 200℃, and a holding time of 5s to 30s. Then, cool water is passed into the inner water channel of the glue injection mechanism for 10s to 30s to cool the hot melt adhesive rapidly to cool and harden, thereby filling the gap and covering the end of the negative electrode extension to form an insulating support portion. Figure 2 and Figure 3 A schematic cross-sectional view is shown.

[0076] Specifically, Figure 2 is a schematic cross-sectional view along the width direction of the pole piece, Figure 3 is a schematic cross-sectional view along the length direction of the pole piece. Figure 2 , 3 As shown, a negative electrode film layer 1'b is formed on the surface of the negative electrode current collector 1'a, a solid electrolyte film (not shown in the figure) is formed on the surface of the negative electrode film layer 1'b, and a positive electrode film layer 2'b is formed on the surface of the positive electrode current collector 2'a. The negative electrode sheets 1' and the positive electrode sheets 2' are alternately stacked. On the outside of the stack and around the entire circumference of the stack (that is, on the Figure 2 and Figure 3 Insulating support portions 3' are formed on both sides in the horizontal direction in the cross-sectional view of FIG. 1 , filling the gap between adjacent negative electrode sheets 1' and covering the ends thereof. Figure 3In the embodiment, there is an empty foil area on the negative electrode current collector 1'a where the negative electrode film layer 1'b is not formed, the portion of the empty foil area close to the negative electrode film layer 1'b is covered by the insulating support portion 3', and the portion away from the negative electrode film layer 1'b constitutes the negative electrode tab. Similarly, there is an empty foil area on the positive electrode current collector 2'a where the positive electrode film layer 2'b is not formed, the portion of the empty foil area close to the positive electrode film layer 2'b is covered by the insulating support portion 3', and the portion away from the positive electrode film layer 2'b constitutes the positive electrode tab, and the positive electrode tab and the negative electrode tab are located on the same side of the stack.

[0077] Encapsulation

[0078] The aluminum-plastic film is packaged in an environment with an ambient humidity of 0.03% to 0.05% and -60degc to -55degc, and then negative pressure is drawn to seal the solid-state battery to ensure that the solid-state battery is isolated from the environment.

[0079] compression

[0080] A warm isostatic pressing treatment is carried out in an atmospheric environment, wherein the warm isostatic pressing parameters are a pressure of 100 MPa or more and 2000 MPa or less and 600 MPa or less, a temperature of 10°C or more and 2000°C or less, and a time of 5 seconds or more and 6000 seconds or less. A solid-state battery is obtained by applying six-sided pressurization.

[0081] In addition, the third aspect of the present application provides an electrical device, which includes the secondary battery of the present application or the secondary battery obtained by the preparation method of the present application. The secondary battery can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.

[0082] Example

[0083] 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 techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0084] Example 1

[0085] (1) Electrode

[0086] In an environment with an ambient humidity of 0.04% and -60 degrees Celsius, a negative electrode slurry (the negative electrode active material is Si compound) is coated on the negative electrode current collector (copper) to form a negative electrode film layer, which is then dried and cold pressed to form a negative electrode sheet. Then, a solid electrolyte (sulfide) is gravure-coated on the negative electrode film layer of the negative electrode sheet to form a solid electrolyte membrane. In addition, a positive electrode slurry (the positive electrode active material is a high-nickel ternary material) is coated on the positive electrode current collector (aluminum foil) to form a positive electrode film layer, which is then dried and cold pressed to form a positive electrode sheet.

[0087] (2) Stacking

[0088] Under the environment of ambient humidity of 0.04% and -60degc, the negative electrode sheet / positive electrode sheet / negative electrode sheet / positive electrode sheet / negative electrode sheet (each electrode sheet is a quadrilateral) is alternately stacked by a stacking machine. After stacking, the protruding length of the protruding part of the negative electrode sheet extending outward is greater than 2mm compared with the positive electrode sheet.

[0089] The obtained stack is configured from bottom to top in sequence: a negative electrode film layer (the active material is Si compound), a portion of a negative electrode current collector, a negative electrode film layer (the active material is Si compound), a solid electrolyte layer (sulfide), a positive electrode film layer (the active material is a high-nickel ternary material), a portion of a positive electrode current collector, and a positive electrode film layer (the active material is a high-nickel ternary material).

[0090] (3) Hot pressing

[0091] Hot pressing is performed in an environment with an ambient humidity of 0.04% and -60 degrees Celsius, with hot pressing parameters of 7 MPa, 90° C. and 120 seconds, so that the solid-state battery obtained in step (2) maintains a relatively stable structure and avoids pole piece dislocation caused by looseness.

[0092] (4) Filling

[0093] The hot-pressed solid-state battery is placed in a glue injection mold, and one side of the glue injection mold is 1mm larger than the outer contour of the solid-state battery. After sealing, hot melt glue (polyolefin) is injected. The injection pressure is 0.5Mpa, the temperature is 200°C, and the holding time is 10s. Then, cooling water is passed through the inner water channel of the glue injection mechanism for 10s to make the polyolefin cool and harden rapidly, filling and fixing the negative electrode sheet beyond the position of the positive electrode sheet, thereby forming insulating support parts on the four sides of the stack.

[0094] (5) Packaging

[0095] Then, the battery is packaged with aluminum-plastic film at an ambient humidity of 0.04% and -60 degrees Celsius, and then negative pressure is drawn to seal the battery to ensure that the solid-state battery is isolated from the environment.

[0096] (6) Compression

[0097] In an atmospheric environment, a warm isostatic press (warm isostatic pressing parameters are 600 MPa, 90°C, 30 min) is used to perform six-sided pressurization to produce a solid-state battery.

[0098] Example 2

[0099] The same preparation method as in Example 1 was used except that Kraft AB adhesive was used as the hot melt adhesive.

[0100] Comparative Example 1

[0101] The same procedure as in Example 1 was carried out except that the (4) filling step was not carried out.

[0102] Next, the safety performance of the all-solid-state batteries obtained in the examples and comparative examples was evaluated.

[0103] The electrode stacks of Examples 1 and 2 were photographed by CT at 150 KV, 120 uA and a cutting depth of 5 mm, confirming that the negative electrode sheets were not broken. Figure 4 CT image of the solid-state battery of Example 1. Figure 4 It can be seen that the hot melt adhesive fills the gap and covers the end of the extended portion of the negative electrode, the electrode piece is not broken, and the battery is safe. Furthermore, the solid-state battery of the embodiment was disassembled, and it was confirmed again that no electrode piece was broken.

[0104] In addition, the solid-state battery of comparative example 1 was disassembled to confirm that the electrode was broken and there was copper overlap. The disassembled part was photographed with a digital camera, and the obtained photos are as follows: Figure 5 shown. Figure 5 In the area shown in the black box, copper leakage occurs and a short circuit occurs inside the battery.

[0105] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, characterized in that: comprising a first pole piece, a second pole piece and an insulating support portion, The first pole piece and the second pole piece are alternately stacked along a first direction to form a stacked body. The first pole piece has a protruding portion protruding outward compared to the second pole piece, and a gap is formed between the protruding portions adjacent to each other in the first direction. The insulating support portion includes a filling portion and a covering portion, the filling portion filling the gap portion, and the covering portion covering an end portion of the protruding portion.

2. The secondary battery according to claim 1, wherein The filling part is connected to the covering part and fills the gap part. Optionally, the filling portion is filled to an end portion of the second pole piece located in the gap portion.

3. The secondary battery according to claim 1 or 2, wherein: The height of the filling portion in the first direction is equal to the height of the gap portion in the first direction.

4. The secondary battery according to any one of claims 1 to 3, wherein The covering portion and the filling portion are integrally formed.

5. The secondary battery according to any one of claims 1 to 4, wherein The covering portion covers the entire stacked body along the first direction.

6. The secondary battery according to any one of claims 1 to 5, wherein An insulating support portion is formed outside the stacked body and around the entire circumference of the stacked body.

7. The secondary battery according to any one of claims 1 to 6, wherein The secondary battery comprises N+1 layers of the first pole piece and N layers of the second pole piece, N≥1, A solid electrolyte membrane is disposed between the first pole piece and the second pole piece stacked adjacent to each other in a first direction, The first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.

8. The secondary battery according to claim 7, wherein The laminated body formed with the insulating support portion is subjected to compression processing, The compression treatment is: pressurizing each surface of the stack formed with the insulating support portion under a pressure greater than 0 MPa and less than or equal to 1000 MPa, optionally under a pressure of 50 MPa to 1000 MPa, and optionally, performing isostatic pressing on the stack formed with the insulating support portion.

9. The secondary battery according to any one of claims 1 to 8, wherein The material of the insulating support portion includes a high molecular polymer. Optionally, the glass transition temperature of the high molecular polymer is -30°C to 200°C.

10. A method for preparing a secondary battery, wherein: The steps include: A stacking step: alternately stacking a first pole piece and a second pole piece along a first direction to form a stacked body, wherein the first pole piece is formed with an extension portion extending outward compared to the second pole piece, and a gap portion is formed between adjacent extension portions in the first direction; and Filling step: Filling the gap and the end of the extension portion with a slurry containing a high molecular polymer to form an insulating support portion.

11. The preparation method according to claim 10, wherein: Before the stacking step, a negative electrode film layer is arranged on at least one surface of the negative electrode collector to form the first electrode sheet, a positive electrode film layer is arranged on at least one surface of the positive electrode collector to form the second electrode sheet, and a solid electrolyte is coated on the surface of the first electrode sheet or the second electrode sheet to form a solid electrolyte membrane.

12. The preparation method according to claim 10 or 11, wherein: In the filling step, the slurry is filled by dipping, coating or injecting.

13. The preparation method according to any one of claims 10 to 12, wherein A compression step is also included after the padding step: The surfaces of the laminated body formed with the insulating support portion are pressurized at a pressure greater than 0 MPa and less than or equal to 1000 MPa, and optionally at a pressure of 50 MPa to 1000 MPa. Optionally, the laminated body formed with the insulating support portion is subjected to isostatic pressing.

14. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 9, or a secondary battery obtained by the preparation method according to any one of claims 10 to 13.

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