Electrode plate, preparation method thereof and all-solid-state battery

Abstract

The embodiment of the invention provides an electrode plate, a preparation method thereof and an all-solid-state battery. The electrode plate comprises an electrode current collector and a functional layer positioned on at least one side surface of the electrode current collector; the functional coating comprises the following raw materials: an electrode main material, a conductive agent, a binder, a solid electrolyte and a flexible high-ion conductive substance; the flexible high ionic conductive substance comprises a monomer ionic liquid or a liquid polymer containing a lithium salt. When the electrode plate provided by the invention is used for preparing the all-solid-state battery, the interface impedance of the all-solid-state battery can be effectively reduced, so that the electrical properties such as long-cycle capacity retention rate of the all-solid-state battery are realized.

Description

Technical Field

[0001] The present invention relates to the field of solid-state batteries, and particularly to an electrode sheet, a preparation method thereof, and an all-solid-state battery. Background Art

[0002] Currently, solid-state batteries have attracted great interest from researchers due to their high energy density and safety performance. However, in the application of solid-state batteries, due to the problem of insufficient contact between the solid electrolyte and the positive and negative electrodes in the solid-state battery, the interfacial impedance of the battery is high, which affects a series of battery performances, such as the long cycle life of the battery.

[0003] In existing applications, it is often necessary to install a pressurizing device in the solid-state battery to improve this problem. However, this will increase the mass of the solid-state battery and reduce the energy density, seriously hindering the application of solid-state batteries in the field of consumer batteries.

[0004] In summary, there is an urgent need for a more effective method to reduce the interfacial impedance of all-solid-state batteries. Brief Description of the Drawings

[0005] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0006] Figure 1 Test results of the capacity retention rate after 1000 cycles for Example 1 and Comparative Example 1. Summary of the Invention

[0007] The present invention provides an electrode sheet, a preparation method thereof, and an all-solid-state battery, which can effectively reduce the interfacial impedance of the all-solid-state battery without reducing the energy density of the all-solid-state battery, and further realize the electrical performances such as the long cycle capacity retention rate of the all-solid-state battery, effectively overcoming the defects in the prior art.

[0008] In the first aspect of the present invention, an electrode sheet is provided, including:

[0009] An electrode current collector and a functional layer located on at least one surface of the electrode current collector;

[0010] The raw materials of the functional layer include an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity substance;

[0011] The flexible high-ion conductivity substance includes a monomer ionic liquid or a liquid polymer containing a lithium salt.

[0012] According to an embodiment of the present invention, the monomeric ionic liquid includes at least one of the following: 1-methylimidazole tetrafluoroborate ionic liquid, imidazole-based ionic liquid, pyridine-based ionic liquid, quaternary ammonium ionic liquid, alkenyl-functionalized ionic liquid, sulfonic acid-functionalized ionic liquid, amino-functionalized ionic liquid, hydroxyl-functionalized ionic liquid, and carboxyl-functionalized ionic liquid.

[0013] According to an embodiment of the present invention, the lithium salt-containing liquid polymer includes: a liquid polymer obtained by dissolving at least one lithium salt selected from lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide in a flexible polymer solvent.

[0014] According to an embodiment of the present invention, the flexible polymer solvent is at least one of polyacrylate, polybutylene glycol, and perfluoropolyether.

[0015] According to an embodiment of the present invention, the proportion of the flexible high ionic conductivity substance in the raw materials of the functional layer is 2-10%.

[0016] According to an embodiment of the present invention, the conductive agent includes at least one of the following: acetylene black, carbon nanotubes, carbon black, activated carbon, conductive graphite, Ketjen black, carbon nanotubes, graphene, and nanofibers.

[0017] According to an embodiment of the present invention, the solid electrolyte is a sulfide solid electrolyte.

[0018] According to an embodiment of the present invention, the raw materials of the sulfide solid electrolyte are at least one of Li2S, P2S5, P, LiI, LiCl, P2S3, P2O5, Al2S3, GeS2, SiS2, and SnS2.

[0019] According to an embodiment of the present invention, the proportion of the main electrode material in the raw materials of the functional layer is 60-90%; and / or, the proportion of the solid electrolyte is 5-20%; and / or, the proportion of the conductive agent is 1-5%; and / or, the proportion of the binder is 0.2-3%.

[0020] According to an embodiment of the present invention, the thickness of the electrode sheet is 70-300 μm.

[0021] According to an embodiment of the present invention, the size of the electrode sheet is 10-500 mm.

[0022] According to an embodiment of the present invention, the electrode sheet is a positive electrode sheet.

[0023] According to an embodiment of the present invention, the main electrode material of the positive electrode sheet is at least one of lithium cobaltate, lithium nickel cobalt manganate, lithium-rich manganese-based, and lithium nickel cobalt aluminate.

[0024] According to an embodiment of the present invention, the electrode sheet is a negative electrode sheet.

[0025] In a second aspect of the present invention, a method for preparing an electrode sheet is provided, including:

[0026] Coating a slurry of a main electrode material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity material on an electrode current collector, and obtaining an electrode sheet after drying, rolling, and slitting treatments;

[0027] Wherein, the flexible high-ion conductivity material includes a monomeric ionic liquid or a liquid polymer containing a lithium salt.

[0028] In a third aspect of the present invention, a method for preparing an electrode sheet is provided, including:

[0029] Rolling and cutting a mixture of a main electrode material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity material into a sheet shape, and pasting the cut sheet-like mixture on an electrode current collector to obtain an electrode sheet;

[0030] Wherein, the flexible high-ion conductivity material includes a monomeric ionic liquid or a liquid polymer containing a lithium salt.

[0031] In a fourth aspect of the present invention, a all-solid-state battery is provided, including: the electrode sheet described in the first aspect of the present invention and a solid electrolyte.

[0032] In a fifth aspect of the present invention, an electrical device is provided, including: the all-solid-state battery described in the fourth aspect of the present invention.

[0033] In the implementation of the present invention, there are at least the following beneficial effects:

[0034] In the all-solid-state battery prepared with this electrode sheet, the flexible high-ion conductivity material will infiltrate into the pores between the solid electrolyte and the electrode sheet, and be in close contact with the solid electrolyte particles and the particles in the electrode sheet, thereby increasing the contact area between the electrode sheet and the solid electrolyte in the all-solid-state battery, effectively reducing the interfacial impedance between the electrode sheet and the solid electrolyte in the all-solid-state battery, and further achieving the effect of optimizing the electrical properties such as the long-cycle capacity retention rate of the all-solid-state battery. Specific embodiments

[0035] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below. The specific embodiments listed below only describe the principles and features of the present invention, and the examples given are only used to explain the present invention, not to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] Based on the above introduction of the background art, an embodiment of the present invention provides an electrode sheet, including: an electrode current collector, and a functional layer located on at least one surface of the electrode current collector. Among them, the raw materials of the functional layer include an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity substance, and the flexible high-ion conductivity substance includes a monomeric ionic liquid or a liquid polymer containing a lithium salt.

[0037] Among them, the flexible high-ion conductivity substance refers to a substance with flexibility and high ion conductivity, such as a monomeric ionic liquid or a liquid polymer containing a lithium salt, etc.

[0038] A monomeric ionic liquid is an independent ionic liquid molecule composed of a single organic cation and a corresponding anion, which has not undergone polymerization or cross-linking, is in a liquid state at room temperature, and has characteristics such as high ion conductivity, high fluidity, and high wettability.

[0039] The liquid polymer containing a lithium salt refers to a liquid polymer obtained by dissolving a lithium salt in a flexible polymer solvent, which is in a liquid state at room temperature and has characteristics such as high ion conductivity, high fluidity, and high wettability.

[0040] According to the research of the inventors, using this flexible high-ion conductivity substance as one of the raw materials for preparing the functional layer of the electrode sheet, and using the electrode sheet to prepare an all-solid-state battery. In the obtained all-solid-state battery, due to the high fluidity and high wettability of the flexible high-ion conductivity substance, the flexible high-ion conductivity substance will infiltrate into the pores between the solid electrolyte and the electrode sheet as a pore filler, and be in close contact with the solid electrolyte particles and the particles in the electrode sheet, thereby increasing the contact area between the electrode sheet and the solid electrolyte in the all-solid-state battery, effectively reducing the interfacial impedance between the electrode sheet and the solid electrolyte in the all-solid-state battery, and further achieving the effect of optimizing the electrical properties such as the long-cycle capacity retention rate of the all-solid-state battery.

[0041] In addition, it is worth noting that compared with other liquids such as polyionic liquids, both monomeric ionic liquids and lithium salt-containing liquid polymers have higher ionic conductivities. Therefore, in the present invention, monomeric ionic liquids or lithium salt-containing liquid polymers are selected instead of other liquids such as polyionic liquids as the raw materials for the functional layer of the electrode sheet in order to further ensure a high ionic conductivity between the solid-solid interface of the electrode sheet and the solid electrolyte in the all-solid-state battery, and thus further improve the ionic conductivity of the all-solid-state battery.

[0042] In some embodiments, the monomeric ionic liquid may include at least one of the following:

[0043] 1-methylimidazole tetrafluoroborate ionic liquid, imidazole-based ionic liquid, pyridine-based ionic liquid, quaternary ammonium ionic liquid, alkenyl-functionalized ionic liquid, sulfonic acid-functionalized ionic liquid, amino-functionalized ionic liquid, hydroxyl-functionalized ionic liquid, and carboxyl-functionalized ionic liquid.

[0044] Specifically, the monomeric ionic liquid can be any one of 1-methylimidazole tetrafluoroborate ionic liquid, imidazole-based ionic liquid, pyridine-based ionic liquid, quaternary ammonium ionic liquid, alkenyl-functionalized ionic liquid, sulfonic acid-functionalized ionic liquid, amino-functionalized ionic liquid, hydroxyl-functionalized ionic liquid, and carboxyl-functionalized ionic liquid, or can be composed of any combination of the above substances. For example, it can be composed of two, three or more substances. In this regard, the embodiments of the present invention do not make specific limitations.

[0045] Among them, the above-mentioned single ionic liquid can be commercially purchased or prepared by conventional methods in the art.

[0046] In some embodiments, the lithium salt-containing liquid polymer includes: a liquid polymer obtained by dissolving at least one lithium salt of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide in a flexible polymer solvent.

[0047] Furthermore, in some embodiments, the above-mentioned flexible polymer solvent is at least one of polyacrylate, polybutylene glycol, and perfluoropolyether.

[0048] Specifically, the lithium salt-containing liquid polymer of the present invention can be obtained by dissolving at least one lithium salt of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide in a flexible polymer solvent including at least one of polyacrylate, polybutylene glycol, and perfluoropolyether.

[0049] In some embodiments, the proportion of the flexible high ionic conductivity substance in the raw materials of the functional layer of the electrode sheet is 2-10%.

[0050] It should be understood that if the proportion of the flexible high ionic conductivity substance in the raw material of the functional layer is too small, the gaps and holes between the electrode sheet and the solid electrolyte in the all-solid-state battery cannot be fully filled by the flexible high ionic conductivity substance, resulting in an insignificant increase in the interfacial contact area between the two, and thus the interfacial resistance of the all-solid-state battery still maintains a relatively large interfacial impedance; if the proportion of the flexible high ionic conductivity substance in the raw material of the functional layer is too large, the content of the main electrode material in the functional layer will be relatively reduced, thereby reducing the overall energy density of the all-solid-state battery. Therefore, the proportion of the flexible high ionic conductivity substance in the raw material of the functional layer of the electrode sheet is preferably 2-10%.

[0051] Exemplarily, in these embodiments, the proportion of the flexible high ionic conductivity substance in the raw material of the functional layer of the electrode sheet is, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a new range is formed by selecting any two of the foregoing values, and the values taken within the new range.

[0052] In some embodiments, the conductive agent includes at least one of the following: acetylene black, carbon nanotubes, carbon black, activated carbon, conductive graphite, Ketjen black, carbon nanotubes, graphene, and nanofibrous carbon.

[0053] Specifically, the conductive agent can be any one of acetylene black, carbon nanotubes, carbon black, activated carbon, conductive graphite, Ketjen black, carbon nanotubes, graphene, and nanofibrous carbon, or can be composed of any combination of the above substances. For example, it can be composed of two, three or more substances. In this regard, the embodiments of the present invention do not make specific limitations. Such a setting can effectively improve the versatility of the electrode sheet, so that the electrode sheet can meet various different application scenarios.

[0054] In some embodiments, the solid electrolyte can be a sulfide solid electrolyte.

[0055] It should be understood that in the raw material of the functional layer of the electrode sheet provided by the present invention, the solid electrolyte can be a commonly used solid electrolyte in the art. Therefore, in some other embodiments, the solid electrolyte can be other solid electrolytes such as oxide solid electrolytes, polymer solid electrolytes, and halide solid electrolytes.

[0056] It should be noted that, compared with other solid electrolytes (such as oxide solid electrolytes), sulfide electrolytes have higher ductility. Using sulfide electrolytes as the raw material for the functional layer of the electrode sheet enables the electrode sheet to have better interfacial contact performance, which can further reduce the interfacial impedance of all-solid-state batteries. Additionally, compared with other solid electrolytes (such as halide solid electrolytes and oxide solid electrolytes), sulfide solid electrolytes have a relatively low density. Using sulfide electrolytes as the raw material for preparing all-solid-state batteries can help improve the energy density of all-solid-state batteries. Moreover, compared with other solid electrolytes (such as oxide solid electrolytes and polymer solid electrolytes), sulfide solid electrolytes have higher ionic conductivity, which can enable the electrode sheet to have a high ion transport efficiency, and thus make all-solid-state batteries have more excellent electrical properties such as ionic conductivity and rate performance.

[0057] Further, in some embodiments, if the solid electrolyte is a sulfide electrolyte, the raw material of the sulfide solid electrolyte is at least one of Li2S, P2S5, P, LiI, LiCl, P2S3, P2O5, Al2S3, GeS2, SiS2, SnS2.

[0058] Specifically, the raw material of the sulfide electrolyte can be any one of Li2S, P2S5, P, LiI, LiCl, P2S3, P2O5, Al2S3, GeS2, SiS2, SnS2, or can be composed of any combination of the above substances. For example, it can be composed of two, three or more substances. In this regard, the embodiments of the present invention do not make specific limitations. Such a setting can effectively improve the versatility of the electrode sheet, enabling the electrode sheet to meet various different application scenarios.

[0059] In some embodiments, the proportion of the main electrode material in the raw material of the functional layer is 60 - 90%; and / or, the proportion of the solid electrolyte is 5 - 20%; and / or, the proportion of the conductive agent is 1 - 5%; and / or, the proportion of the binder is 0.2 - 3%.

[0060] Exemplarily, in these embodiments, in the raw materials of the functional layer, the proportion of the main electrode material is, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any two of the foregoing values are selected to form a new range, and the values taken within the new range; and / or, the proportion of the solid electrolyte is, for example, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20%, or any two of the foregoing values are selected to form a new range, and the values taken within the new range; and / or, the proportion of the conductive agent is, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any two of the foregoing values are selected to form a new range, and the values taken within the new range; and / or, the proportion of the binder is, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any two of the foregoing values are selected to form a new range, and the values taken within the new range.

[0061] For example, in one embodiment, in the raw materials of the functional layer, the main electrode material: solid electrolyte: conductive agent: ionic liquid: binder is 80:15:1:2:2.

[0062] In some embodiments, the electrode sheet provided by the present invention is a positive electrode sheet. It should be understood that when the electrode sheet is a positive electrode sheet, the main positive electrode material of the positive electrode sheet can be a commonly used positive electrode active material in the art, for example, at least one composite oxide of a metal of lithium and cobalt, manganese, nickel and their combinations.

[0063] Further, in some embodiments, when the electrode sheet is a positive electrode sheet, the main electrode material of the positive electrode sheet is at least one of lithium cobaltate, lithium nickel cobalt manganate, lithium-rich manganese-based, and lithium nickel cobalt aluminate.

[0064] In some embodiments, the electrode sheet provided by the present invention is a negative electrode sheet. It should be understood that when the electrode sheet is a negative electrode sheet, the main negative electrode material of the negative electrode sheet can be a commonly used negative electrode active material in the art, for example, at least one of graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials (mainly including silicon monoxide and silicon-carbon negative electrodes), and tin-based negative electrode materials (mainly including tin and tin alloys).

[0065] In a specific implementation of the present invention, the binder in the raw materials of the functional layer of the electrode sheet can be a commonly used binder in the art. Exemplarily, if the electrode sheet is a positive electrode sheet, the binder is, for example, at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, a polymer containing ethylene oxide, polyvinylpyrrolidone, and polyurethane; if the electrode sheet is a negative electrode sheet, the binder is, for example, at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyvinyl alcohol, and sodium polyacrylate.

[0066] In some embodiments, the thickness of the electrode sheet is 70 - 300 μm.

[0067] It should be understood that in the actual application of the present invention, when designing and preparing the electrode sheet, the thickness of the positive electrode sheet and the negative electrode sheet in the all-solid-state battery can be correspondingly adjusted according to the molar ratio or mass ratio of the positive electrode active material to the negative electrode active substance in the designed all-solid-state battery (i.e., the N / P ratio of the all-solid-state battery).

[0068] Exemplarily, in these embodiments, the thickness of the electrode sheet is, for example, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, 210 μm, 230 μm, 250 μm, 270 μm, 290 μm, 300 μm, or a new range is formed by selecting any two of the foregoing values, and the values taken within the new range.

[0069] In some embodiments, the size of the electrode sheet is 10 - 500 mm. It should be understood that in the actual application of the present invention, the size of the electrode sheet can be adjusted according to the application scenario of the all-solid-state battery prepared using the electrode sheet (such as mobile phones or new energy vehicles, etc.) and performance requirements (such as requirements for the energy density of the all-solid-state battery, etc.).

[0070] Exemplarily, in these embodiments, the size of the electrode sheet is, for example, 10 mm, 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, or a new range is formed by selecting any two of the foregoing values, and the values taken within the new range.

[0071] An embodiment of the present invention provides a method for preparing an electrode sheet, including: coating a slurry of an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high ionic conductivity substance on an electrode current collector, and obtaining the electrode sheet after drying, rolling, and slitting treatments; wherein, the flexible high ionic conductivity substance includes a monomeric ionic liquid or a liquid polymer containing a lithium salt.

[0072] It should be understood that the preparation process of the above-mentioned method for preparing an electrode sheet is a commonly used wet synthesis process in the art. Exemplarily, specifically, the raw materials of the functional layer of the electrode sheet can be mixed with a solvent, and the mixed substances can be stirred and dispersed until completely mixed evenly to obtain an electrode slurry; then the electrode slurry is coated on the electrode current collector, and the electrode sheet is obtained after drying, rolling, and slitting treatments. Among them, if the electrode sheet is a positive electrode sheet, the electrode current collector can be at least one of aluminum foil and nickel foil; if the electrode sheet is a negative electrode sheet, the electrode current collector can be at least one of copper foil, nickel foam, and copper foam. Among them, the solvent is completely removed during the drying process of the electrode sheet.

[0073] It is worth noting that in the above-mentioned method for preparing the electrode sheet provided by the present invention, no more energy needs to be consumed, no additional preparation steps need to be added, only the required flexible high ionic conductivity substance needs to be added during the slurry mixing process, which is convenient for rapid popularization and application in industrial production. By using this preparation method, the electrode sheet provided by the present invention can be prepared. When the electrode sheet is applied in a all-solid-state battery, the flexible high ionic conductivity substance in the electrode sheet can infiltrate into the pores between the solid electrolyte and the electrode sheet, and be in close contact with the solid electrolyte particles and the particles in the electrode sheet, thereby increasing the contact area between the electrode sheet and the solid electrolyte in the all-solid-state battery, effectively reducing the interfacial impedance between the electrode sheet and the solid electrolyte in the all-solid-state battery, and further achieving the effect of optimizing the electrical properties such as the long-cycle capacity retention rate of the all-solid-state battery.

[0074] An embodiment of the present invention provides a method for preparing an electrode sheet, including: mixing an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high ionic conductivity substance and rolling them into a sheet and cutting, and pasting the cut sheet mixture on an electrode current collector to obtain the electrode sheet; wherein, the flexible high ionic conductivity substance includes a monomeric ionic liquid or a liquid polymer containing a lithium salt.

[0075] It should be understood that the preparation process of the above-mentioned method for preparing an electrode sheet is a dry synthesis process.

[0076] It should be noted that in the above-provided preparation method capable of preparing the electrode sheet provided by the present invention, there is no need to consume more energy, and there is no need to additionally increase the preparation steps. Only the required flexible high-ion conductivity substance needs to be added during the slurry mixing process, without consuming more energy and without additionally increasing the preparation steps. Only the required flexible high-ion conductivity substance needs to be added during the raw material mixing process, which is convenient for rapid popularization and application in industrial production. By using this preparation method, the electrode sheet provided by the present invention can be prepared and obtained. When this electrode sheet is applied in a all-solid-state battery, the flexible high-ion conductivity substance in the electrode sheet can infiltrate into the pores between the solid electrolyte and the electrode sheet, and be in close contact with the solid electrolyte particles and the particles in the electrode sheet, thereby increasing the contact area between the electrode sheet and the solid electrolyte in the all-solid-state battery, effectively reducing the interfacial impedance between the electrode sheet and the solid electrolyte in the all-solid-state battery, and further achieving the effect of optimizing the electrical properties such as the long-cycle capacity retention rate of the all-solid-state battery.

[0077] An embodiment of the present invention provides a all-solid-state battery, including: the electrode sheet provided by the present invention and a solid electrolyte.

[0078] Specifically, the all-solid-state battery of the present invention is assembled from a positive electrode sheet and a negative electrode sheet obtained by using the preparation method of the electrode sheet provided by the present invention, and a solid electrolyte, and can be prepared by a conventional method in the art.

[0079] Exemplarily, in a specific embodiment of the present invention, the following method can be used to prepare the all-solid-state battery provided by the present invention: mix the solid electrolyte and a binder, roll them into a sheet and cut it to obtain a sheet-shaped solid electrolyte; stack the positive electrode sheet prepared by using the preparation method of the electrode sheet provided by the present invention, the sheet-shaped solid electrolyte, and the negative electrode sheet prepared by using the preparation method of the electrode sheet provided by the present invention in sequence, and then place them in an aluminum-plastic bag and seal to obtain a solid-state battery; place the solid-state battery in an isostatic press with a water temperature of 70 °C for pressurization to obtain the all-solid-state battery provided by the present invention, wherein the static pressure of the isostatic press is 400 MPa and the pressure holding time is 30 min.

[0080] Optionally, the static pressure of the isostatic press can be 20 - 600 MPa, the water temperature can be 30 - 80 °C, and the pressure holding time can be 5 - 30 min.

[0081] The interfacial impedance between the solid electrolyte and the electrode sheet in the all-solid-state battery provided by the present invention is reduced, and the electrical properties such as the long-cycle capacity retention rate of the all-solid-state battery are effectively improved.

[0082] An embodiment of the present invention provides an electrical device, including: the all-solid-state battery provided by the present invention.

[0083] The type of the electrical device of the present invention is not particularly limited, and it can be any electrical device including the battery, including but not limited to electric vehicles, mobile phones, portable devices, laptop computers, electric bicycles, electric toys, energy storage devices, etc.

[0084] The present invention will be further introduced below through specific embodiments.

[0085] Example 1

[0086] 1. Preparation of the positive electrode sheet:

[0087] After mixing the electrode main material, solid electrolyte, conductive agent, flexible high-ion conductivity substance and binder in a ratio of 80:15:1:2:2, roll them into a sheet with a thickness of 150 μm to obtain a sheet mixture. Among them, the electrode main material is lithium cobaltate, the solid electrolyte is Li3PS4, the conductive agent is conductive carbon black, and the flexible high-ion conductivity substance is 1-methylimidazole tetrafluoroborate; use a cutting machine to cut the sheet mixture into a size of 50 mm × 60 mm, and paste the cut sheet mixture on the aluminum foil to obtain the positive electrode sheet.

[0088] 2. Preparation of the negative electrode sheet:

[0089] After mixing the electrode main material, solid electrolyte, conductive agent, flexible high-ion conductivity substance and binder in a ratio of 80:15:1:2:2, roll them into a sheet with a thickness of 2000 μm to obtain a sheet mixture. Among them, the electrode main material is graphite, the solid electrolyte is Li3PS4, the conductive agent is conductive carbon black, and the flexible high-ion conductivity substance is 1-methylimidazole tetrafluoroborate; use a cutting machine to cut the sheet mixture into a size of 53 mm × 63 mm, and paste the cut sheet mixture on the copper foil to obtain the negative electrode sheet.

[0090] 3. Treatment of the solid-state battery:

[0091] Mix Li3PS4 and the binder and roll them into a sheet mixture with a thickness of 200 μm, and use a cutting machine to cut the sheet mixture into a size of 55 mm × 65 mm to obtain a sheet-shaped solid electrolyte.

[0092] 4. Assembly of the all-solid-state battery:

[0093] Stack the positive electrode sheet prepared by the electrode sheet preparation method provided by the present invention, the sheet-shaped solid electrolyte, and the negative electrode sheet prepared by the electrode sheet preparation method provided by the present invention in sequence, and then place them in an aluminum-plastic bag and seal to obtain a solid-state battery; place the solid-state battery in an isostatic press with a water temperature of 70 °C and apply pressure under the conditions of a static pressure of 400 MPa and a pressure holding time of 30 min to obtain an all-solid-state battery.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that a flexible high ionic conductivity substance was not added during the preparation of the positive electrode sheet and the negative electrode sheet, and a pressure device was provided in the prepared all-solid-state battery.

[0096] Next, the cycle performance of the all-solid-state batteries prepared in the above Example 1 and Example 2 will be tested under the following conditions: the ambient temperature is 30 °C, the all-solid-state battery is not clamped by a clamping plate and not pressurized, and constant current charging and discharging are carried out at 0.1C, the voltage change range is 2.5 - 4.25V, and the charge and discharge cycle is 1000 times. The capacity retention rate Q after 1000 cycles = Q 1000 / Q1 * 100%.

[0097] Figure 1 Table 1 shows the test results of the capacity retention rates of Example 1 and Comparative Example 1 after 1000 cycles. As Figure 1 shown, the capacity retention rate of the all-solid-state battery in Example 1 after 1000 cycles reached 95%, and the capacity retention rate of the all-solid-state battery in Comparative Example 1 after 1000 cycles was 0%, and the capacity retention rate became 0% when the cycle reached the 200th cycle. It can be seen that adding a flexible high ionic conductivity substance to the raw materials of the functional layer of the electrode sheet can greatly improve the long-cycle capacity retention rate of the all-solid-state battery prepared using this electrode sheet.

[0098] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode sheet, characterized in that, Comprising: An electrode current collector, and a functional layer located on at least one surface of the electrode current collector; The raw materials of the functional layer include an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity substance; The flexible high-ion conductivity substance includes a monomeric ionic liquid or a lithium salt-containing liquid polymer.

2. The electrode sheet according to claim 1, characterized in that, The monomeric ionic liquid includes at least one of the following: 1-methylimidazole tetrafluoroborate ionic liquid, imidazole-based ionic liquid, pyridine-based ionic liquid, quaternary ammonium ionic liquid, alkenyl-functionalized ionic liquid, sulfonic acid-functionalized ionic liquid, amino-functionalized ionic liquid, hydroxy-functionalized ionic liquid, and carboxyl-functionalized ionic liquid.

3. The electrode sheet according to claim 1, wherein The lithium salt-containing liquid polymer includes: A liquid polymer obtained by dissolving at least one lithium salt selected from lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide in a flexible polymer solvent.

4. The electrode sheet according to claim 3, wherein The flexible polymer solvent is at least one of polyacrylate, polybutylene glycol, and perfluoropolyether.

5. The electrode sheet according to any one of claims 1 to 4, characterized in that, The proportion of the flexible high-ion conductivity substance in the raw materials of the functional layer is 2-10%.

6. The electrode sheet according to any one of claims 1 to 4, characterized in that, The conductive agent includes at least one of the following: Acetylene black, carbon nanotubes, carbon black, activated carbon, conductive graphite, Ketjen black, carbon nanotubes, graphene, and nanofibers.

7. The electrode sheet according to any one of claims 1 to 4, characterized in that, The solid electrolyte is a sulfide solid electrolyte.

8. The electrode sheet according to claim 7, wherein, The raw materials of the sulfide solid electrolyte are at least one of Li2S, P2S5, P, LiI, LiCl, P2S3, P2O5, Al2S3, GeS2, SiS2, and SnS2.

9. The electrode sheet according to any one of claims 1 to 4, characterized in that, In the raw materials of the functional layer The proportion of the electrode main material is 60-90%; and / or, The proportion of the solid electrolyte is 5-20%; and / or, The proportion of the conductive agent is 1-5%; and / or, The proportion of the binder is 0.2-3%.

10. The electrode sheet according to any one of claims 1 to 4, characterized in that, The thickness of the electrode sheet is 70-300 μm.

11. The electrode sheet according to any one of claims 1 to 4, characterized in that, The size of the electrode sheet is 10-500 mm.

12. The electrode sheet according to any one of claims 1 to 4, characterized in that, The electrode sheet is a positive electrode sheet.

13. The electrode sheet according to claim 12, characterized in that, The electrode main material of the positive electrode sheet is at least one of lithium cobaltate, lithium nickel cobalt manganate, lithium-rich manganese-based, and lithium nickel cobalt aluminate.

14. The electrode sheet according to any one of claims 1 to 4, characterized in that, The electrode sheet is a negative electrode sheet.

15. A method for preparing an electrode sheet, characterized in that, Comprising: Coating a slurry of an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity substance on an electrode current collector, and obtaining an electrode sheet after drying, rolling, and slitting; Wherein, the flexible high-ion conductivity substance includes a monomeric ionic liquid or a lithium salt-containing liquid polymer.

16. A method for preparing an electrode sheet, characterized in that, Comprising: Rolling and cutting a mixture of an electrode main material, a conductive agent, a binder, a solid electrolyte, and a flexible high-ion conductivity substance into a sheet, and pasting the cut sheet-like mixture on an electrode current collector to obtain an electrode sheet; Wherein, the flexible high-ion conductivity substance includes a monomeric ionic liquid or a lithium salt-containing liquid polymer.

17. A all-solid-state battery, characterized in that, Comprising: The electrode sheet according to any one of claims 1 to 14 and a solid electrolyte.

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