Preparation method of all-solid-state battery, all-solid-state battery and all-solid-state battery module

Abstract

The invention discloses a preparation method of an all-solid-state battery unit, the all-solid-state battery unit and an all-solid-state battery module. The preparation method comprises the following steps: 1) pressing and pre-calcining a positive electrode unit to form a sintered laminated body; (2) alternately overlapping at least one negative electrode and the sintered laminated body in the step (1) to form an all-solid-state battery laminated body, and pressurizing the laminated body; (3) carrying out low-temperature primary calcination on the all-solid-state battery laminated body in the step (2); (4) carrying out high-temperature secondary calcination on the all-solid-state battery laminated body obtained in the step (3); wherein the positive electrode unit in the step 1 comprises a solid electrolyte layer, a composite electrode layer and a current collector layer; the composite electrode layer comprises a high ion channel layer and a high electron channel layer. The stable particle space is constructed through multiple times of calcination, the interface impedance between the electrode layer and the electrolyte layer and the interface impedance between the electrode layers are reduced, the densification between the solid electrolyte and the electrode is improved, and the battery capacity and the cycle performance are improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an all-solid-state battery and a preparation method thereof, as well as an all-solid-state battery module having the all-solid-state battery. Background Art

[0002] All-solid-state batteries, which use solid-state electrolytes instead of traditional liquid electrolytes, fundamentally resolve the flammable and explosive safety hazards of liquid batteries. They also have the potential for higher energy density and longer cycle life, and are therefore considered a key development direction for the next generation of energy storage technology. However, the current development of all-solid-state batteries faces problems such as large pores, poor interfacial impedance, and low electrode ion conductivity. Although existing technologies with high-ion and high-electron channel layers can improve ion and electronic conductivity, the rigid interface between the electrode layers causes solid-solid contact, resulting in significant interfacial impedance and prone to contact failure due to volume changes during cycling. Summary of the Invention

[0003] To address the aforementioned issues, this application discloses a method for preparing an all-solid-state battery, an all-solid-state battery, and an all-solid-state battery module. The all-solid-state battery features a multi-gradient stacked structure that improves electronic and ionic conductivity. It also utilizes a stepwise calcination process to reduce interfacial impedance, thereby enhancing battery capacity and cycle performance.

[0004] The first aspect of the present application discloses a method for preparing an all-solid-state battery. The preparation method may include: 1) pressing and pre-calcining a positive electrode unit to form a sintered laminate; 2) alternately overlapping at least one negative electrode with the sintered laminate in step 1 to form an all-solid-state battery stack, and pressurizing the stack; 3) performing a low-temperature primary calcination on the all-solid-state battery stack in step 2; 4) performing a high-temperature secondary calcination on the all-solid-state battery stack in step 3; wherein the positive electrode unit in step 1 includes a solid electrolyte layer, a composite electrode layer, and a current collector layer; the composite electrode layer includes a high ion channel layer and a high electron channel layer.

[0005] According to some embodiments of the present application, the solid electrolyte layer may include a first binder and a first solid electrolyte; wherein the mass proportion of the first binder is 1 to 5%, and the mass proportion of the first solid electrolyte is 95 to 99%; and the thickness of the solid electrolyte layer is 10 to 30 μm.

[0006] According to some embodiments of the present application, the high ion channel layer may include a first positive electrode active material, a first conductive agent, a second binder and a second solid electrolyte; wherein the mass proportion of the first conductive agent is 1 to 3%, and the mass proportion of the second solid electrolyte is 14 to 20%; the thickness of the high ion channel layer is 5 to 20 μm.

[0007] According to some embodiments of the present application, the high electron channel layer may include a second positive electrode active material, a second conductive agent, a third binder and a third solid electrolyte; wherein the mass proportion of the second conductive agent is 14 to 20%, and the mass proportion of the third solid electrolyte is 1 to 3%; the thickness of the high electron channel layer is 5 to 20 μm.

[0008] According to some embodiments of the present application, the current collector layer may include a fourth binder and a current collector; wherein the mass proportion of the fourth binder is 1-5%, the mass proportion of the current collector is 95-99%; and the thickness of the current collector layer is 5-10 μm.

[0009] According to some embodiments of the present application, the pre-calcination temperature of the sintered laminate in step 1) may be 800-1200°C.

[0010] According to some embodiments of the present application, the low-temperature primary calcination temperature of the stacked body in step 3) may be 400-500°C.

[0011] According to some embodiments of the present application, the high-temperature secondary calcination temperature of the laminate in step 4) may be 900-1100°C.

[0012] A second aspect of the present application provides an all-solid-state battery, wherein the solid-state battery cell can be prepared based on the preparation method described above.

[0013] A third aspect of the present application provides an all-solid-state battery module, which may include a plurality of all-solid-state batteries as described above that are arranged in sequence and electrically connected.

[0014] In this application, the electrode is formed into a multi-gradient laminated composite electrode using a multi-gradient lamination method, which improves the electronic and ionic conductivity of the electrode. In addition, a stepwise calcination method is used to construct a stable particle space, reduce the interfacial impedance between the composite electrode layers, and improve the densification between the solid electrolyte and the electrode. This reduces the pores and interfacial impedance between the layers while ensuring contact stability during the battery cycle, thereby improving the battery capacity and cycle performance.

[0015] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure of this application will be more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the figures represent similar components, where:

[0017] Figure 1is an exemplary flow chart of a method for preparing an all-solid-state battery according to some embodiments of the present application;

[0018] Figure 2 is a schematic diagram of an exemplary structure of a positive electrode according to some embodiments of the present application;

[0019] Figure 3 This is a schematic diagram of an exemplary structure of an all-solid-state battery according to some embodiments of the present application. DETAILED DESCRIPTION

[0020] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. Words such as "include" or "comprise" used in this application mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The terms "and / or" or "and / or" used in this application include any and all combinations of one or more related listed items.

[0022] Some preferred embodiments of the present application are described below. It should be noted that the following description is for illustrative purposes and is not intended to limit the scope of protection of the present application. The steps involved in the present application can be performed precisely in order, or various steps can be processed in reverse order or simultaneously. At the same time, other operations can be added to these processes, or one or more operations can be removed from these processes.

[0023] This application discloses a method for preparing an all-solid-state battery. Figure 1 The method 100 for preparing the all-solid-state battery may include the following steps.

[0024] Step 1: The positive electrode unit is pressed and pre-calcined to form a sintered laminate.

[0025] In some embodiments, the positive electrode unit may include a solid electrolyte layer, a composite electrode layer, and a current collector layer. The composite electrode layer may include a high ion channel layer and a high electron channel layer. Figure 2The exemplary structure of the positive electrode 200 shown may include a solid electrolyte layer 210 and a composite electrode layer 220 stacked in sequence, wherein the composite electrode layer 220 includes a high ion channel layer 221 and a high electron channel layer 222, and a current collector layer 230. As an exemplary but non-limiting description, the solid electrolyte layer 210 may be prepared from a first binder and a first solid electrolyte.

[0026] In some embodiments, the mass ratio between the above two materials can be 1wt%-5wt% of the first binder and 95wt%-99wt% of the first solid electrolyte material. For example, 1wt% of the first binder and 99wt% of the first solid electrolyte, 2wt% of the first binder and 98wt% of the first solid electrolyte, 3wt% of the first binder and 97wt% of the first solid electrolyte, 4wt% of the first binder and 96wt% of the first solid electrolyte, 5wt% of the first binder and 95wt% of the first solid electrolyte material, etc. Or it can be any value within the numerical range of the two materials, and this application does not impose any restrictions on this.

[0027] In some embodiments, the solid electrolyte layer 210 can be prepared by coating, laminating, depositing, or other methods using a uniformly mixed powder of the aforementioned materials. Preferably, the first binder and the first solid electrolyte material, weighed in a mass ratio, can be jet milled to uniformly mix the mixture, and the resulting mixture can be pressed into a sheet to obtain a solid electrolyte layer 210 of a target thickness.

[0028] In some embodiments, the thickness of the solid electrolyte layer 210 may be 10-30 μm, for example, 10 μm, 20 μm, 30 μm, etc., or any value within this numerical range, which is not limited in this application.

[0029] The high ion channel layer 221 can be used to accelerate the migration of ions (e.g., lithium ions Li+) and reduce the ion transport resistance. As an exemplary but non-limiting description, the high ion channel layer 221 can be prepared from a first positive electrode active material, a first conductive agent, a second binder, and a second solid electrolyte. For example, it can be prepared from 80wt% of the first positive electrode active material, 1wt%-3wt% of the first conductive agent, 2wt% of the second binder, and 14wt%-20wt% of the second solid electrolyte. By introducing a high ion conductivity solid electrolyte material as the ion transport skeleton of the electrode, the ion conductivity of the electrode is improved.

[0030] In some embodiments, the ratio of the first positive electrode active material, the first conductive agent, the second binder and the second solid electrolyte can be 80:1:2:17, 80:2:2:16, 80:3:2:15, etc., and then mixed and molded, or any value within the numerical range of the two materials. This application does not impose any restrictions on this.

[0031] In some embodiments, the above materials may be jet milled to achieve uniform mixing. The resulting mixture may also be tableted or coated.

[0032] In some embodiments, the above mixture may be coated on one side surface of the solid electrolyte layer 210 (for example, Figure 2 A high ion channel layer 221 is formed on the lower surface of the solid electrolyte layer 210 as shown. The thickness of the formed high ion channel layer 220 can be 5 to 20 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, etc., or any value within this numerical range, and this application does not impose any limitation on this.

[0033] The high electron channel layer 222 can be used to enhance rapid electron conduction and reduce electron transport hysteresis. As an exemplary but non-limiting illustration, the high electron channel layer 222 can be prepared from a second positive electrode active material, a second conductive agent, a third binder, and a third solid electrolyte. For example, it can be prepared from 80 wt% of the second positive electrode active material, 14 wt%-20 wt% of the second conductive agent, 2 wt% of the third binder, and 1 wt%-3 wt% of the third solid electrolyte.

[0034] In some embodiments, the ratio of the second active material, the second conductive agent, the third binder and the third solid electrolyte can be 80:15:2:3, 80:16:2:2, 80:17:2:1, etc., and then mixed and molded, or any value within the numerical range of the two materials. This application does not impose any restrictions on this.

[0035] In some embodiments, raw materials of a predetermined mass ratio are weighed and then put into a jet mill for jet milling to obtain a uniform mixture. The obtained mixture can also be tableted or coated.

[0036] In some embodiments, the above mixture may be coated on one side surface of the high ion channel layer 221 (for example, Figure 2 A high electron channel layer 222 is formed on the lower surface of the high ion channel layer 221 as shown. The thickness of the formed high electron channel layer 222 can be 5 to 20 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, etc., or any value within this numerical range, and this application does not impose any limitation on this.

[0037] In some embodiments, the current collector layer 230 may be prepared from a fourth binder and a current collector. The current collector may include at least one or more of silver, palladium, gold, platinum, aluminum, copper, nickel, and carbon.

[0038] In some embodiments, the current collector layer 230 can be unipolar or bipolar based on the material of the current collector selected. For example, a bipolar current collector layer 230 can be realized by using copper and aluminum on both sides.

[0039] In some embodiments, the current collector layer 230 can be prepared by weighing the fourth binder and the current collector in a predetermined mass ratio and then mixing them in a mixer. For example, a powdered binder and nanosilver can be mixed in an air flow mixer. The mixing parameters, such as air flow rate, mixing temperature, and mixing time, are set to thoroughly mix the ingredients. The resulting mixture is then pressed, coated, or the like to produce the current collector layer 230.

[0040] In some embodiments, the current collector layer 230 may include 1 wt% to 5 wt% of the fourth binder and 95 wt% to 99 wt% of the current collector. For example, the mass ratio of the fourth binder to the current collector material in the current collector layer 230 is 1:99, 2:98, 3:97, 4:96, 5:95, or any other value within the numerical range of the two materials, and this application does not impose any limitation thereto.

[0041] In some embodiments, after the above materials are evenly mixed, the current collector layer 230 can be formed on one side surface of the high electron channel layer 222 by coating (for example, Figure 2 The thickness of the formed current collector layer 230 can be 5 to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., or any value within this numerical range, and this application does not impose any limitation on this.

[0042] In the present application, the layers constituting the positive electrode unit are stacked in sequence and then pre-calcined to form the sintered laminate. For example, the above-mentioned components are prepared separately by a dry method, a wet method or an existing available preparation method, and then stacked in sequence. Another implementation method may be to prepare the above-mentioned components in sequence to achieve stacking. For example, the solid electrolyte layer 210 can be first prepared by a dry method or a wet method, and then the uniform mixture for preparing the high ion channel layer 220 is coated on one side surface of the solid electrolyte layer 210, such as by screen printing, dry spraying, electrostatic spraying, plasma spraying, etc. or other available spraying methods. In this way, a high ion channel layer 221 can be formed on one side of the solid electrolyte layer 210. Similarly, a high electron channel layer 222 can be formed by coating on one side surface of the high ion channel layer 221, and a current collector layer 230 can be formed by coating on one side surface of the high electron channel layer 222. Of course, the preparation order of the above components can also be reversed, that is, first prepare the current collector layer 230 using a dry method or a wet method, and then sequentially coat the high electron channel layer 222, the high ion channel layer 221, and the solid electrolyte layer 210. This is not a limitation.

[0043] In some embodiments, the stacked positive electrode unit can be pressed and pre-calcined. For example, a hot press, a roller press, an isostatic press (e.g., warm isostatic press), or the like can be used for pressing. The pressed positive electrode unit can be transferred to a protective atmosphere for pre-calcination to obtain the sintered laminate.

[0044] In some embodiments, pre-calcination can be performed in a protective atmosphere at a heating rate of 2 to 8°C / min to a calcination temperature of 800°C to 1200°C, and then calcined for 3 to 6 hours. The protective atmosphere can include one of nitrogen, helium, argon, etc. The heating rate can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, etc. The calcination temperature can be 800°C, 900°C, 1000°C, 1100°C, 1200°C, etc. The calcination time can be 3 hours, 4 hours, 5 hours, 6 hours, etc. The above heating rate, calcination temperature, and calcination time can be adjusted according to actual needs and are not specifically limited in this application.

[0045] After pre-calcination, the interface problems of the composite electrode layer itself in the obtained positive electrode unit and the interface problems between the composite electrode layer and the solid electrolyte layer can be solved.

[0046] Step 2: alternately stacking at least one negative electrode and the sintered laminate in step 1 to form an all-solid-state battery stack, and pressurizing the stack.

[0047] In some embodiments, the alternating overlap between the negative electrode and the sintered laminate may be an overlap in which the active material layer of the negative electrode contacts the solid electrolyte layer of the sintered laminate. Figure 3 The exemplary structure diagram of the all-solid-state battery shown in the figure shows that the bottom layer is a sintered laminate 310 made of a positive electrode unit, wherein the solid electrolyte layer 210 is located on the surface. The negative electrode 320 is then stacked. After the stacking is completed, the sintered laminate 310 is stacked again. At this time, the solid electrolyte layer 210 is located at the bottom layer, stacked opposite the negative electrode 320. Using the bipolar current collector layer 230, the negative electrode can be stacked again on the sintered laminate located on the third layer. The stacking of the above three components is repeated in this way, and the stacking is stopped after the predetermined number of layers is reached, and the stacked body is finally obtained.

[0048] The laminate can be pressed using the same or similar methods, such as a hot press, a roller press, an isostatic press, etc. For example, a warm isostatic press, a cold isostatic press, etc. can be used, but are not limited thereto. The pressing time and pressure can be adjusted according to actual conditions and are not specifically limited in this application.

[0049] Step 3: calcining the all-solid-state battery stack described in step 2 once at a low temperature.

[0050] In some embodiments, the low-temperature primary calcination can be used to remove binders, including the first binder, the second binder, the third binder, and the fourth binder. Removing binders can enhance the interfacial contact between the layers of the solid-state battery cell, reduce interfacial resistance, and lower the internal resistance of the battery, thereby increasing battery capacity and cycle life.

[0051] In some embodiments, the low-temperature primary calcination can be carried out under a protective atmosphere at a heating rate of 2 to 8°C / min to a calcination temperature of 400°C to 500°C and calcined for 2 to 5 hours. The protective atmosphere can include one of nitrogen, helium, argon, etc. The heating rate can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, etc. The calcination temperature can be 400°C, 450°C, 500°C, etc. The calcination time can be 2 hours, 3 hours, 4 hours, 5 hours, etc. The above heating rate, calcination temperature, and calcination time can be adjusted according to actual needs and are not specifically limited in this application.

[0052] Step 4: The all-solid-state battery stack described in step 3 is subjected to a second high-temperature calcination.

[0053] In some embodiments, the high-temperature secondary calcination may be densification sintering to promote solid-phase diffusion between particles and form a dense structure. After the high-temperature secondary calcination is completed, natural cooling is performed to finally obtain the all-solid-state battery.

[0054] In some embodiments, the high-temperature secondary calcination can be carried out under a protective atmosphere at a heating rate of 2 to 8°C / min to a calcination temperature of 900°C to 1100°C and calcined for 4 to 8 hours. The protective atmosphere can include one of nitrogen, helium, argon, etc. The heating rate can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, etc. The calcination temperature can be 900°C, 1000°C, 1100°C, etc. The calcination time can be 4h, 5h, 6h, 7h, 8h, etc. The above heating rate, calcination temperature, and calcination time can be adjusted according to actual needs and are not specifically limited in this application.

[0055] In some embodiments, the two calcinations of the laminate can be performed in nitrogen, and the two calcinations can be performed in the same oven without material transfer.

[0056] The preparation method of the all-solid-state battery disclosed in this application adopts a stepwise calcination method to construct a stable particle space, reduce the interface impedance between the composite electrode layers, and improve the densification between the solid electrolyte and the composite electrode layer. Therefore, while reducing the pores and the interface impedance between the layers, it can ensure the contact stability of the battery during the cycle process and improve the battery capacity and cycle performance.

[0057] In the above description, the binding agent (comprising the first binding agent, the second binding agent, the third binding agent and the fourth binding agent) can use any known binding agent including but not limited to polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, polyhexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose etc. or its arbitrary combination can be used for the present application.Copolymer can also be used as binding agent, and exemplary can be the copolymer of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene etc. Or, the mixture of two or more materials in the above example can also be used as binding agent. In some implementations, any binder that can be gasified and separated from the laminate within the calcination temperature (400° C. to 500° C.) during the first calcination of the shaping calcination can be used in the present application.

[0058] The above solid electrolytes (including the first solid electrolyte, the second solid electrolyte and the third solid electrolyte) may include but are not limited to halide solid electrolyte materials, sulfide solid electrolyte materials, polymer solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, hydride solid electrolytes, borate solid electrolytes, inorganic compound-polymer mixed solid electrolytes, etc.

[0059] Some suitable but non-limiting halide solid electrolytes may include, but are not limited to, LaF3, LiCl, LiI, etc. or a solid electrolyte with the chemical formula Li a MX b represents a lithium halide solid electrolyte, wherein M represents a metal element or a metalloid element, including one or more of B, Si, Ge, As, Sb, Te, Al, Zn, Mg, Ca, Ba, Mn, Cd, Co, Yb, Y, Cr, In, Ga, Sr, Hf, Ti, Ta, Sn, Nb, Er, Sc, etc., and X represents a halogen element such as F, Cl, Br, I, etc. For example, Li2CdCl4, Li2MgCl4, Li2CdI4, Li2ZnI4, Li2ZrCl6, Li3YCl6, Li3InCl6, etc.

[0060] Some suitable but non-limiting sulfide solid electrolytes may include but are not limited to Li2S-P2S5, Li2S-P2S5–MS x (M=Si, Ge, Sn, 0≤x≤2), Li 9.6 P3S 12 、Li7P3S 11 、Li7P2S8I、Li 10 SnP2S 12 、Li 10 SiP2S 12 、Li9P3S9O3、LGPS(Li 10 GeP2S 12 )、Thio-LISICON(Li 3.25 Ge 0.25 P 0.75 S4), Li6PS5X (X=Cl, Br, I), Li3PS4-X (X=Cl, Br, I), Li4SnS4-X (X=Cl, Br), Li 3.25 Ge 0.25 P 0.75 S4, Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 、Li 9.54 Si1.74 P 1.44 S 11.7 Cl 0.3 、Li 10.35 Ge 1.35 P 1.65 S 12 、Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 10 (Si 0.5 Ge 0.5 )P2S 12 、Li 10 (Ge 0.5 Sn 0.5 )P2S 12 、Li 10 (Si 0.5 Sn 0.5 )P2S 12 、Li6(PS5) 0.7 (GeS4) 0.3 Cl, Li 7.5 P 2.5 Sn 0.5 S 10.5 Cl 1.5 、Li6PS5Cl 0.5 Br 0.5 、Li6PS5I 0.2 Cl 0.8 、Li5SnS2Cl3、Li 10 P3S 12 Cl2、Li7P2S 8.5 Cl 0.5 etc. or any combination thereof.

[0061] Some suitable but non-limiting polymer solid electrolytes may include, but are not limited to, polyethylene oxide (PEO)-based electrolytes, polyphenylene ether (PPO)-based electrolytes, polyvinylidene fluoride (PVDF)-based electrolytes, polymethyl methacrylate (PMMA)-based electrolytes, polyacrylonitrile (PAN)-based electrolytes, and the like.

[0062] Some suitable but non-limiting oxide solid electrolytes may include, but are not limited to, NASICON type solid electrolytes such as LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, Li 1+x Al x Ge 2-x(PO4)3(LAGP, where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4)3(LATP, where 0 ≤ x ≤ 2), Li 1+x Y x Zr 2-x (PO4)3(LYZP, where 0 ≤ x ≤ 2), Li 1.3 Al 0.3 Ti 1.7 (PO4)3, etc., perovskite-type solid electrolytes such as Li 3x La( 2 / 3-x )TiO3(LLTO, where 0 < x < 0.25), LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3(where x = 0.75y and 0.60 < y < 0.75), etc., LISICON-type solid electrolytes such as Li 14 ZnGe4O 16 、Li4SiO4、LiGeO4, etc., garnet-type solid electrolytes such as Li7La3Zr2O 12 、Li 6.5 La3Zr 1.75 Te 0.25 O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La3Zr2O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 etc., etc. or any combination thereof.

[0063] Some suitable but non-limiting nitride solid electrolytes may include, but are not limited to, Li3N, Li7PN4, LiSi2N3, Li9N2Cl3, and the like.

[0064] Some suitable but non-limiting hydride solid electrolytes may include, but are not limited to: LiBH4, LiBH4-Li X (X=Cl, Br or I), LiNH2, Li2NH, LiBH4-LiNH2, Li3AlH6, etc.

[0065] Some suitable but non-limiting borate solid electrolytes may include but are not limited to Li2B4O7, Li2O-B2O3-P2O5, Li2B 10 H 10 -Li2B 12 H 12 , Li7N2I-0.5LiOH, etc.

[0066] Some suitable but non-limiting inorganic compound-polymer mixed solid electrolytes may include, but are not limited to, LLZO-PEO composite electrolytes, LLZO-PVDF composite electrolytes, POSS-based organic-inorganic hybrid electrolytes, and the like.

[0067] Derivatives of the above electrolytes obtained by substitution, doping, modification, and compounding can also be used as solid electrolyte materials in this application. For example, Li2ZrCl6 substituted or partially substituted with bromine (Br), such as Li2ZrCl 6-x Br x , rare earth metals such as lanthanum or yttrium doped Li6PS5Br, LLZO deposited on the surface of indium (In), etc. It should be noted that the above examples are only for illustrative purposes and are not intended to limit the present application.

[0068] In some implementations, the solid electrolyte may be an oxide solid electrolyte material, for example, lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LATP), garnet-type solid electrolytes such as lithium lanthanum zirconium oxide (Li7La3Zr2O 12 , LLZO), perovskite solid electrolytes such as lithium lanthanum titanium oxide (Li 0.33 La 0.56 One of TiO3, LLTO).

[0069] The positive electrode active material may include a material capable of intercalating or deintercalating metal ions such as lithium ions, including but not limited to layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel cobalt manganese oxide (LiNi x Cox Mn 1-2x O2, NCM), lithium nickel cobalt aluminum oxide (LiNi 0.8 Co 0.15 Al 0.05 O2, NCA) or compounds substituted by one or more transition metals; lithium manganese oxides such as Li 1+x Mn 2-x O4 (x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxides such as Li2CuO2; vanadium compounds such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; 1-x M x Lithium nickel oxide represented by O2 (wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, including at least one of the above elements, wherein x is 0.01 to 0.3); 2-x M x Lithium manganese composite oxide represented by the formula Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x O4 is a spinel lithium manganese composite oxide; the Li part in the LiMn2O4 formula is replaced by alkaline earth metal ions; LiNi x Co y Mn (1-x-y) O2 (where x = 0.8, y = 0.1); disulfide; Fe2(MoO4)3; lithium cobalt oxide; lithium iron phosphate; elemental sulfur (S8); Li2Sn (n = 1), organic sulfur compounds or carbon-sulfur polymers (C2S x ) n (x is 2.5 to 50, n is 2); it may include sulfur compounds, etc.

[0070] The negative electrode active material may include a lithium host material that is capable of storing lithium. Exemplary negative electrode active materials may include carbonaceous materials such as graphite, hard carbon, soft carbon, silicon, silicon-carbon mixtures, lithium titanate (Li4Ti5O 12 ), transition metals such as Sn, metal oxides or metal sulfides such as TiO2, FeS, SnO2, etc., and other negative electrode active materials that accept lithium such as lithium-indium (Li-In).

[0071] The above conductive agents (including the first conductive agent, the second conductive agent, etc.) may include but are not limited to graphites such as natural graphite and artificial graphite, conductive carbon black (Super P), acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black and other carbon blacks, carbon fibers such as VGCF, metal fibers and other conductive fibers, metal powders such as carbon fluoride, aluminum powder, nickel powder, etc., conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, polyaniline, polypyrrole, polythiophene, polyphenylene derivatives and other conductive polymers, etc., or a mixture of two or more thereof. The present application also discloses an all-solid-state battery, which can be prepared based on the above method.

[0072] The present application also discloses an all-solid-state battery module, which is formed by folding, stacking, or combining the above multiple all-solid-state batteries and electrically connecting them to each other.

[0073] The present application is further described in detail below with reference to the following examples. It should be noted that the following examples are only used to illustrate the present application and are not intended to limit the scope of protection claimed in the present application.

[0074] Example 1 - Preparation of all-solid-state battery cells

[0075] 1) Preparing a solid electrolyte layer: Mixing a first binder PTFE and a first solid electrolyte LATP in a mass ratio of 5:95 by jet milling to prepare a solid electrolyte layer with a thickness of 20 μm;

[0076] 2) Preparation of a high ion channel layer: The first cathode active material, lithium nickel cobalt manganese oxide NCM523, the first conductive agent, conductive carbon black, the second binder PTFE, and the second solid electrolyte LATP, in a mass ratio of 80:2:2:16, were mixed by air jet milling and coated on the surface of the solid electrolyte layer by screen printing to form a high ion channel layer on the surface of the solid electrolyte layer with a thickness of 15 μm;

[0077] 3) Preparing a high electron channel layer: The second positive electrode active material, lithium nickel cobalt manganese oxide NCM523, the second conductive agent, conductive carbon black, the third binder PTFE, and the third solid electrolyte LATP, in a mass ratio of 80:16:2:2, were mixed by air flow milling and coated on the surface of the high ion channel layer by screen printing to form a high electron channel layer on the surface of the high ion channel layer with a thickness of 15 μm;

[0078] 4) Preparation of the current collector layer: Finally, the fourth binder PVDF and the current collector Ag in a mass ratio of 5:95 were mixed by air flow milling and coated on the surface of the high electron channel layer by screen printing to form a current collector layer on the surface of the high electron channel layer with a thickness of 5 μm, forming a positive electrode unit.

[0079] 5) Precalcination:

[0080] The positive electrode unit was hot-pressed at 70°C, with the current collector, composite electrode, and solid electrolyte laminated in sequence. The laminate was then cut to produce a sintered laminate. The laminate was then heated to 1000°C in a nitrogen-filled reactor at a rate of 5°C / min for 5 hours to form a sintered laminate.

[0081] 6) Preparation of all-solid-state battery cells:

[0082] The active material layer of the silicon-carbon negative electrode is alternately overlapped with the sintered positive electrode unit (in contact with the solid electrolyte layer in the positive electrode unit) to form 10 layers. The laminate is subjected to isostatic pressing at room temperature of 25°C and the pressure is controlled at 100 MPa to improve the adhesion.

[0083] 7) First forming and calcining:

[0084] Under a nitrogen atmosphere, the all-solid-state battery stack was heated to 400° C. at a heating rate of 5° C. / min and calcined for 3 h to remove the binder.

[0085] 8) Second forming and calcining:

[0086] Under a nitrogen atmosphere, the all-solid-state battery stack without the binder was heated to 1000°C at a heating rate of 5°C / min and calcined for 6 hours for densification sintering. After sintering, it was naturally cooled to obtain an all-solid-state battery unit.

[0087] Example 2 - Preparation of all-solid-state battery cells

[0088] Compared with Example 1, the preparation method used is the same, except that the first binder is SBR and the first solid electrolyte is Li7La3Zr2O 12 The first positive electrode active material is lithium iron phosphate, the first conductive agent is acetylene black, the second binder is SBR, and the second solid electrolyte is Li7La3Zr2O 12 The second positive electrode active material is lithium iron phosphate, the second conductive agent is acetylene black, the third binder is SBR, and the third solid electrolyte is Li7La3Zr2O 12 ; The fourth adhesive is PAA and the current collector is aluminum foil.

[0089] Example 3 - Preparation of all-solid-state battery cells

[0090] Compared with Example 1, the materials and preparation methods used are the same, except that the mass ratio of the first positive electrode active material lithium nickel cobalt manganese oxide NCM523, the first conductive agent conductive carbon black, the second binder PTFE and the second solid electrolyte LATP in the high ion channel layer is 80:3:2:15.

[0091] Example 4 - Preparation of all-solid-state battery cells

[0092] Compared with Example 1, the materials and preparation methods used are the same, except that the mass ratio of the second positive electrode active material lithium nickel cobalt manganese oxide NCM523, the second conductive agent conductive carbon black, the third binder PTFE and the third solid electrolyte LATP in the high electron channel layer is 80:15:2:3.

[0093] Comparative Example 1- Preparation of all-solid-state battery cells

[0094] Compared with Example 1, the materials and preparation methods used are the same, except that the positive electrode units are not pre-calcined after lamination, and the all-solid-state battery stack with alternating positive electrode units and negative electrodes is directly calcined twice.

[0095] Comparative Example 2-All-solid-state battery cell preparation

[0096] Compared with Example 1, the positive electrode unit in Comparative Example 2 is not multi-gradient stacked, and only one positive electrode active layer is provided, which is prepared from active material, conductive agent, binder and solid electrolyte material in a mass ratio of 80:2:2:16.

[0097] Test Example - Capacity Retention Test

[0098] At a temperature of 25°C, first charge at a constant current of 0.2C to a charge termination voltage of 4.2V, then switch to constant voltage charging. When the current drops to the cut-off current of 0.02C, charging stops and the battery is left to stand for 30 minutes. Then discharge at a constant current of 0.2C to a discharge termination voltage of 3.0V, and the discharge capacity of the battery is obtained.

[0099] The test steps for the capacity retention rate after 100 cycles are as follows: At 25°C, first charge at a constant current of 0.2C to a charge end voltage of 4.2V, then switch to constant voltage charging. When the current drops to the cut-off current of 0.02C, charge is stopped and the battery is left standing for 30 minutes. Then, discharge at a constant current of 0.2C to a discharge end voltage of 3.0V, with an interval of at least 60 minutes between charge and discharge. After 100 cycles, the capacity retention rate after 100 cycles can be obtained by comparing the initial capacity. The results are shown in Table 1.

[0100] Table 1: All-solid-state battery cell capacity test results

[0101] capacity 100-cycle capacity retention rate Example 1 15.3 95％ Example 2 14.5 96％ Example 3 14.9 94.4％ Example 4 14.8 94.5％ Comparative Example 1 6.3 80％ Comparative Example 2 11.6 88％

[0102] As shown in Table 1, the all-solid-state battery cell (Example 1) with a multi-gradient stacked composite electrode and obtained by multiple calcinations has a higher battery capacity than the all-solid-state battery cell without pre-calcination (Comparative Example 1) and the all-solid-state battery cell without pre-calcination (Comparative Example 2) with a non-gradient composite electrode and without pre-calcination, and the capacity retention rate is higher, with better battery cycle performance. Example 2 is to change the material used in each layer, and the battery capacity is slightly lower than that in Example 1, but its capacity retention rate is improved, and the battery has good comprehensive performance, indicating that the preparation method of the present application is equally applicable to different materials; Example 3 and Example 4 are to change the material mass ratio of the high ion channel layer and the material mass ratio of the high electron channel layer respectively, and in Example 3, the high ion channel layer increases the conductive agent content and reduces the solid electrolyte content. The battery capacity and capacity retention rate are both slightly downward compared with Example 1, and in Example 4, the high electron channel layer reduces the conductive agent content and increases the solid electrolyte content. The battery capacity and capacity retention rate are also slightly reduced compared with Example 1.

[0103] While the basic concepts have been described herein, it will be apparent to those skilled in the art that the detailed disclosure herein is merely illustrative and does not constitute a limitation of the present application. Although not expressly provided herein, those skilled in the art may make various modifications, improvements, and amendments to the present application. Such modifications, improvements, and amendments are suggested herein and remain within the spirit and scope of the exemplary embodiments of the present application.

[0104] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this application does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0105] Similarly, it should be noted that, in order to simplify the description of this application and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment or its description. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, the features of an embodiment may be fewer than all the features of the individual embodiments disclosed above.

[0106] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other variations may also fall within the scope of this application. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this application may be considered consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly introduced and described in this application.

Claims

1. A method for preparing an all-solid-state battery, characterized in that: The preparation method comprises: 1) Pressing and pre-calcining the positive electrode unit to form a sintered laminate; 2) alternately stacking at least one negative electrode and the sintered laminate in step 1 to form an all-solid-state battery stack, and pressurizing the stack; 3) performing a low-temperature primary calcination on the all-solid-state battery stack described in step 2; 4) performing a secondary high-temperature calcination on the all-solid-state battery stack described in step 3; Wherein, the positive electrode unit in step 1 includes a solid electrolyte layer, a composite electrode layer and a current collector layer; the composite electrode layer includes a high ion channel layer and a high electron channel layer.

2. The preparation method according to claim 1, characterized in that The solid electrolyte layer includes a first binder and a first solid electrolyte; wherein the mass proportion of the first binder is 1-5%, and the mass proportion of the first solid electrolyte is 95-99%; the thickness of the solid electrolyte layer is 10-30 μm.

3. The preparation method according to claim 1, characterized in that The high ion channel layer includes a first positive electrode active material, a first conductive agent, a second binder and a second solid electrolyte; wherein the mass proportion of the first conductive agent is 1 to 3%, and the mass proportion of the second solid electrolyte is 14 to 20%; the thickness of the high ion channel layer is 5 to 20 μm.

4. The preparation method according to claim 1, characterized in that The high electron channel layer includes a second positive electrode active material, a second conductive agent, a third binder and a third solid electrolyte; wherein the mass proportion of the second conductive agent is 14-20%, the mass proportion of the third solid electrolyte is 1-3%; the thickness of the high electron channel layer is 5-20 μm.

5. The preparation method according to claim 1, characterized in that The current collector layer includes a fourth binder and a current collector; wherein the mass proportion of the fourth binder is 1-5%, and the mass proportion of the current collector is 95-99%; the thickness of the current collector layer is 5-10 μm.

6. The preparation method according to claim 1, characterized in that The pre-calcination temperature of the sintered laminate in step 1) is 800-1200°C.

7. The preparation method according to claim 1, characterized in that The low-temperature primary calcination temperature of the stacked body in step 3) is 400-500°C.

8. The preparation method according to claim 1, characterized in that The high-temperature secondary calcination temperature of the laminate in step 4) is 900-1100°C.

9. An all-solid-state battery, characterized in that: The all-solid-state battery is prepared by the preparation method according to any one of claims 1 to 9.

10. An all-solid-state battery module, characterized in that: The all-solid-state battery module includes a plurality of all-solid-state batteries as described in any one of claims 1 to 9 that are arranged in sequence and electrically connected.

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