Negative pole piece as well as preparation method and application thereof

Abstract

The invention relates to a negative pole piece as well as a preparation method and application thereof. The negative pole piece comprises a current collector and a coating material attached to one side of the current collector, the coating material comprises a negative electrode active material and a polymer wrapped on the surface and in gaps of the negative electrode active material; the polymer polar group forms a sodium ion transmission channel; when the working temperature of the all-solid-state sodium-ion battery is greater than or equal to the glass-transition temperature of the polymer, the all-solid-state sodium-ion battery is charged and discharged in a cycle process; sodium ions in the negative pole piece and polar groups on the molecular chain segment of the polymer are subjected to complexation and decomplexation along the molecular chain segment, so that the sodium ions are transmitted along the molecular chain segment, a sodium ion transmission channel is formed, and the sodium ions are transmitted on the molecular chain segment; therefore, the first-circle coulombic efficiency and the reversible capacity of the all-solid-state sodium-ion battery are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a negative electrode plate and a preparation method and application thereof. Background Art

[0002] In order to reduce carbon emissions and achieve sustainable social development, the development of new energy vehicles has become a strategic direction that my country focuses on supporting. So far, the development of lithium-ion battery technology has gradually improved and has been widely used in various fields such as portable electronic devices, aerospace, new energy vehicles, and large-scale energy storage devices. With the emergence of the problem of flammable and explosive liquid electrolytes, researchers have focused on solid electrolytes. Due to its certain mechanical properties, improved electrolyte energy density, stable interface, and non-flammable advantages, it has become an emerging research hotspot.

[0003] Similar to all-solid-state lithium batteries, all-solid-state sodium batteries usually use metallic sodium or sodium alloys on the negative electrode side to ensure the high energy density of the battery. However, metallic sodium is more active than lithium and has certain safety risks in large-scale applications. Therefore, the preparation of alternative negative electrodes is the only way for all-solid-state sodium batteries in the future.

[0004] In view of the fact that the silicon negative electrode has a large volume change during the battery cycle, which increases the application risk of the battery, we choose to modify the traditional hard carbon to a certain extent. Most of the related research on the application of composite hard carbon in all-solid-state sodium-ion batteries is to mix about 30% of inorganic electrolytes (borohydrides, sulfides, halides, etc.) into hard carbon to improve the ion diffusion coefficient of the negative electrode during the solid-state battery cycle and alleviate the strong side reactions between the electrode material and the inorganic solid electrolyte. Summary of the invention

[0005] The embodiment of the present invention provides a negative electrode plate and a preparation method and application thereof, the purpose of which is to solve the problem of improving the interface transmission of the negative electrode of the existing solid-state sodium battery. A small amount of polymer containing polar groups is added to the negative electrode active material, thereby improving the ionic conductivity of the negative electrode plate and also improving the battery energy density.

[0006] The present invention adds a polymer containing polar groups and having the ability to complex with alkali metal cations during the preparation of the negative electrode pole piece, so that the surface of the negative electrode active material is wrapped by the polymer, sodium ions are transmitted through the polymer chain segments, and a transmission channel for sodium ions in the negative electrode is constructed, thereby relatively improving the ion transmission efficiency of the negative electrode material; the negative electrode pole piece is applied to an all-solid-state sodium ion battery, which can improve the first-cycle coulomb efficiency of the all-solid-state sodium ion battery and the stable reversible cycle of the all-solid-state sodium ion battery.

[0007] The present invention is different from the traditional composite electrode material made by adding a large amount of inorganic electrolyte. The proportion of the introduced polymer additive is low, which increases the proportion of active substances in the composite negative electrode material. While improving the first cycle coulomb efficiency of the battery, it also ensures the specific energy density of the negative electrode material. In addition, the polymer additive used in the present invention is safer than some inorganic solid electrolytes (such as sulfide solid electrolytes and halide solid electrolytes) and has a wider application prospect.

[0008] To this end, in a first aspect, an embodiment of the present invention provides a negative electrode plate, the negative electrode plate comprising: a current collector, and a coating material attached to one side or both sides of the current collector.

[0009] The coating material comprises: a negative electrode active material, and a polymer coated on the particle surface of the negative electrode active material and filled in the particle gaps of the negative electrode active material.

[0010] The polymer is obtained in situ or ex situ on the negative electrode sheet.

[0011] The polymer has polar groups on its molecular chain segments.

[0012] The negative electrode plate is used in an all-solid-state sodium ion battery. When the operating temperature of the all-solid-state sodium ion battery is greater than or equal to the glass transition temperature of the polymer, when the all-solid-state sodium ion battery performs a charge and discharge cycle, the sodium ions in the negative electrode plate and the polar groups on the molecular chain segments of the polymer undergo a complexation and decomplexation process along the molecular chain segments, so that the sodium ions are transported along the molecular chain segments to form a sodium ion transmission channel.

[0013] Preferably, the negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; the mass of the negative electrode active material accounts for 50%-99% of the total mass of the coating material.

[0014] The polar groups of the polymer include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds; the mass of the polymer accounts for 1%-30% of the total mass of the coating material.

[0015] The current collector includes copper foil or aluminum foil.

[0016] Further preferably, the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; and the silicon-based material includes silicon-oxygen material and / or silicon-carbon composite material.

[0017] The titanium-based materials include: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [L i 0.22 T i 0.78 ]O2、Na 0.6 [Cr 0.6 Ti 0.4 ]One or more of Na2T i OPO4, Na2T i2(PO4)3.

[0018] The polymer specifically includes: one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane.

[0019] Preferably, the coating material further comprises a binder and a sodium salt.

[0020] The binder comprises: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxymethyl cellulose, polyacrylic acid, polytetrafluoroethylene, and sodium alginate; the binder accounts for 0-10% of the total mass percentage of the coating material.

[0021] The coating material further comprises sodium salt; the sodium salt comprises: NaFS I and / or NaTFS I; the sodium salt accounts for 0-20% of the total mass percentage of the coating material.

[0022] In a second aspect, an embodiment of the present invention provides a method for preparing the negative electrode sheet described in the first aspect, and the preparation method comprises:

[0023] The negative electrode active material, polymer, sodium salt and binder are added into the solvent and stirred evenly to obtain the negative electrode slurry.

[0024] The negative electrode slurry is coated on one or both sides of the current collector, cut or sliced ​​after drying, and then vacuum dried to obtain a negative electrode sheet containing the coating material.

[0025] The polymer is a polymer containing polar groups; wherein the polar groups include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds.

[0026] Preferably, the negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; wherein, the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the silicon-based material includes silicon-oxygen materials and / or silicon-carbon composite materials; the titanium-based material includes: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [L i 0.22 T i 0.78 ]O2、Na 0.6 [Cr 0.6 T i 0.4 ]One or more of Na2T i OPO4, Na2T i2(PO4)3.

[0027] The polymer includes: one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane.

[0028] The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene.

[0029] The sodium salt includes: NaFS I and / or NaTFS I.

[0030] The mass ratio of the negative electrode active material, polymer, sodium salt and binder is [50-90]:

[0031] [1-30]:[0-20]:[0-10].

[0032] The solvent includes deionized water or N-methylpyrrolidone.

[0033] The current collector includes copper foil or aluminum foil.

[0034] The drying temperature is 80° C.-100° C., and the drying time is 40 minutes-8 hours.

[0035] The vacuum drying temperature is 120° C., and the vacuum drying time is 10 hours to 15 hours.

[0036] In a third aspect, an embodiment of the present invention provides a method for preparing the negative electrode sheet described in the first aspect, and the preparation method comprises:

[0037] The negative electrode active material, polymer precursor material, sodium salt and binder are dissolved in a solvent and stirred evenly to obtain a negative electrode slurry.

[0038] The negative electrode slurry is coated on one side of the current collector, and dried at the polymerization temperature of the polymer precursor material to form a polymer in situ on the surface of the current collector. After cutting or slicing, the negative electrode sheet containing the coating material is obtained.

[0039] The polymer is a polymer containing polar groups; wherein the polar groups include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, amide groups and their derivatives, carbamoyl groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds.

[0040] Preferably, the negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; wherein the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the silicon-based material includes silicon-oxygen materials and / or silicon-carbon composite materials; the titanium-based material includes: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [Li 0.22 T i 0.78 ]O2、Na 0.6 [Cr 0.6 T i 0.4 ]One or more of Na2T iOPO4, Na2T i2(PO4)3.

[0041] The polymer specifically includes: one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane.

[0042] The sodium salt includes: NaFS I and / or NaTFS I.

[0043] The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene.

[0044] The mass ratio of the negative electrode active material, the polymer precursor material, the sodium salt and the binder is [50-90]: [1-30]: [0-20]: [0-10].

[0045] The solvent includes deionized water or N-methylpyrrolidone.

[0046] The current collector includes copper foil or aluminum foil.

[0047] In a fourth aspect, an embodiment of the present invention provides an all-solid-state sodium ion battery, comprising a positive electrode plate, a solid electrolyte membrane, and a negative electrode plate as described in any one of claims 1 to 4 above.

[0048] Preferably, the solid electrolyte membrane is prepared by one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-organic composite solid electrolyte.

[0049] The positive electrode active material of the positive electrode plate includes any one of phosphates, ternary materials, vanadium oxides, vanadates, transition metal oxides, Prussian blue compounds, and polyanion compounds.

[0050] The embodiment of the present invention provides a negative electrode plate and a preparation method and application thereof. A polymer containing polar groups and having the ability to complex with alkali metal cations is added during the preparation of the negative electrode plate, so that the surface of the negative electrode active material is wrapped by the polymer, sodium ions are transported through the polymer chain segments, and a transmission channel for sodium ions in the negative electrode is constructed, thereby relatively improving the ion transmission efficiency of the negative electrode material. The negative electrode plate is applied to an all-solid-state sodium ion battery, which can ensure the first-cycle coulomb efficiency of the all-solid-state sodium ion battery and the stable reversible cycle of the all-solid-state sodium ion battery.

[0051] The present invention is different from the traditional composite electrode material made by adding a large amount of inorganic electrolytes. The proportion of the introduced polymer additive is low, which increases the proportion of active substances in the composite negative electrode material. While ensuring the first cycle coulomb efficiency of the battery, it also guarantees the specific energy density of the negative electrode material. In addition, the polymer additive used in the present invention is safer than some inorganic solid electrolytes (such as sulfide solid electrolytes and halide solid electrolytes), and there are many types of polymers and abundant raw materials, which has a relatively broad application prospect.

[0052] The present invention provides a method for preparing a negative electrode plate, wherein the in-situ polymerization preparation method abandons the cumbersome steps of traditional polymer preparation, has simple operation, low cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of the sodium ion transmission principle in the negative electrode plate provided in an embodiment of the present invention.

[0054] Figure 2 A flow chart of a method for preparing a negative electrode plate provided in an embodiment of the present invention.

[0055] Figure 3 A flow chart of another method for preparing a negative electrode plate provided in an embodiment of the present invention.

[0056] Figure 4 This is a first cycle charge and discharge curve diagram of an all-solid-state sodium metal battery assembled with the negative electrode plate provided in Example 1 of the present invention.

[0057] Figure 5 The charge and discharge curves of the first and fifth cycles of the all-solid-state sodium metal battery assembled with the negative electrode plate provided in Example 1 of the present invention.

[0058] Figure 6 This is a first cycle charge and discharge curve diagram of an all-solid-state sodium ion battery assembled with the negative electrode plate provided in Example 1 of the present invention.

[0059] Figure 7 The charge and discharge curves of the first and fifth cycles of the all-solid-state sodium metal battery assembled with the negative electrode plate provided in Example 2 of the present invention.

[0060] Figure 8 This is a first cycle charge and discharge curve diagram of an all-solid-state sodium metal battery assembled with a hard carbon negative electrode sheet provided in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0063] An embodiment of the present invention provides a negative electrode plate, comprising: a current collector, and a coating material attached to one side or both sides of the current collector.

[0064] Wherein, the current collector includes copper foil or aluminum foil.

[0065] The coating material comprises: a negative electrode active material, and a polymer coated on the particle surface of the negative electrode active material and filled in the particle gaps of the negative electrode active material.

[0066] The negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; the mass of the negative electrode active material accounts for 50%-99% of the total mass of the coating material, preferably 85%-90%, and more preferably 85%.

[0067] Among them, the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the precursors of the amorphous carbon material include but are not limited to: one or more of biomass precursors, synthetic resin precursors, and asphalt precursors; among them, the biomass precursors include but are not limited to: one or more of coconut shells, straws, walnut shells, sugar, and starch; the synthetic resin precursors specifically include but are not limited to: phenolic resins and / or epoxy resins.

[0068] Silicon-based materials include, but are not limited to, silicon-oxygen materials and / or silicon-carbon composite materials.

[0069] Titanium-based materials include but are not limited to: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [L i 0.22 T i 0.78 ]O2、Na 0.6 [Cr 0.6 T i 0.4 ]One or more of Na2T i OPO4, Na2T i2(PO4)3.

[0070] The polymer in the coating material has polar groups on its molecular chain segments, and the molecular chain segments containing polar groups can form sodium ion transmission channels on the surface of the negative electrode active material.

[0071] The polar groups of the polymer include: one or more groups selected from the group consisting of hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, mercapto groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds.

[0072] The polymer includes, but is not limited to, one or more of polyethylene glycol (PEG), polystyrene (PS), poly(ethylene glycol) methyl ether methacrylate (PEGMA), 1,3-dioxolane (DOL), polyethylene glycol borate, polyethylene glycol succinate (PE-2,4), poly(β-propiolactone) (PPL), poly(ethylene glycol) methyl ether acrylate (PPEGMA), polyvinyl chloride (PVC), polytrimethylene carbonate (PTMC), polypropylene carbonate (PPC), polycyanoacrylate (PECA), polyoxalate (POE), polyphosphazene (PPN), polyacrylonitrile (PAN), and polysiloxane.

[0073] The mass percentage of the polymer to the total mass of the coating material is 1%-30%, preferably 5%-15%, more preferably 5%.

[0074] The above-mentioned negative electrode plate provided in an embodiment of the present invention is used in an all-solid-state sodium ion battery. When the operating temperature of the all-solid-state sodium ion battery is greater than or equal to the glass transition temperature of the above-mentioned polymer, when the all-solid-state sodium ion battery performs a charge and discharge cycle, the sodium ions in the negative electrode plate and the polar groups on the molecular chain segments of the polymer undergo a complexation and decomplexation process along the molecular chain segments, so that the sodium ions are transmitted along the molecular chain segments to form a sodium ion transmission channel.

[0075] Figure 1 This is a schematic diagram of the sodium ion transport process in the negative electrode plate (taking the hard carbon composite negative electrode as an example). It can be seen that after the hard carbon particles (HC particles in the figure) in the hard carbon composite negative electrode (HC composite negative electrode in the figure) are wrapped by the polymer, the sodium ions are transported between the polar groups of the polymer. The sodium ions (Na in the figure) act with the polar groups on the molecular chain segments (-CC- in the figure), so that the sodium ions are complexed with the polar groups and then decomplexed to achieve the purpose of transporting sodium ions, thereby improving the transmission efficiency of sodium ions and improving the coulombic efficiency of the battery.

[0076] In a preferred embodiment, the coating material further includes a binder and a sodium salt.

[0077] The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxymethyl cellulose, polyacrylamide, and polytetrafluoroethylene; the binder accounts for 0-10% of the total mass percentage of the coating material, preferably 5%.

[0078] The sodium salt includes sodium bis(fluorosulfonyl)imide (NaFS I) and / or sodium bis(trifluoromethylsulfonyl)imide (NaTFSI); the sodium salt accounts for 0-20% of the total mass percentage of the coating material, preferably 5%.

[0079] There are two ways to add the polymer to the negative electrode plate of the present invention. One is to add the polymer directly, and the other is to add the polymer precursor material to generate the polymer in situ.

[0080] The embodiment of the present invention provides a method for preparing the above-mentioned negative electrode sheet, which is to directly add the polymer obtained non-in-situ, such as Figure 2 As shown, the specific steps include the following steps.

[0081] Step 110, adding the negative electrode active material, polymer, sodium salt and binder into the solvent, stirring evenly, to obtain negative electrode slurry.

[0082] The polymer is a polymer containing polar groups, and the polar groups include: one or more groups of hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds; specifically, the polymer includes but is not limited to: polyethylene glycol (PEG), polystyrene (PS) , poly(ethylene glycol) methyl ether methacrylate (PEGMA), 1,3-dioxolane (DOL), polyethylene glycol borate, polyethylene glycol succinate (PE-2,4), poly(β-propiolactone) (PPL), poly(ethylene glycol) methyl ether acrylate (PPEGMA), polyvinyl chloride (PVC), polytrimethylene carbonate (PTMC), polypropylene carbonate (PPC), polycyanoacrylate (PECA), polyoxalate (POE), polyphosphazene (PPN), polyacrylonitrile (PAN), and one or more of polysiloxane.

[0083] The negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials.

[0084] The carbon-based material is an amorphous carbon material, including hard carbon and soft carbon; the precursors of the amorphous carbon material include but are not limited to: one or more of biomass precursors, synthetic resin precursors, and asphalt precursors; wherein the biomass precursors include but are not limited to: one or more of coconut shells, straws, walnut shells, sugar, and starch; the synthetic resin precursors specifically include but are not limited to: phenolic resins and / or epoxy resins.

[0085] Silicon-based materials include silicon-oxygen materials and / or silicon-carbon composite materials; titanium-based materials include but are not limited to: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [L i 0.22 T i 0.78 ]O2、Na0.6 [Cr 0.6 T i 0.4 ]One or more of Na2T i OPO4, Na2T i2(PO4)3.

[0086] The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene.

[0087] Sodium salts include, but are not limited to, NaFS I and / or NaTFS I.

[0088] The mass ratio of the negative electrode active material, the polymer, the sodium salt and the binder is [50-90]: [1-30]: [0-20]: [0-10].

[0089] The solvent includes deionized water or N-methylpyrrolidone; the solid content in the negative electrode slurry is 45wt%-60wt%.

[0090] The stirring in this step can be carried out using conventional equipment to ensure that the material is evenly dispersed in the solvent.

[0091] Step 120, coating the negative electrode slurry on one side or both sides of the current collector, cutting or slicing after drying, and then vacuum drying to obtain a negative electrode sheet containing the coating material.

[0092] Wherein, the current collector includes copper foil or aluminum foil; the coating method of this step is a conventional known method, and the coating thickness is 10 μm-100 μm.

[0093] The drying temperature is between 80℃ and 100℃, and the drying time is 40 minutes to 8 hours. The diameter of the pole piece cut or sliced ​​is 8mm or 12mm round.

[0094] The temperature of vacuum drying is 120° C., and the time of vacuum drying is 10 hours to 15 hours. In this step, vacuum drying is used to remove the solvent in the coating material.

[0095] The embodiment of the present invention provides another method for preparing the above-mentioned negative electrode sheet, in which a polymer is formed in situ on the negative electrode sheet, such as Figure 3 As shown, the specific steps include the following steps.

[0096] Step 210, dissolving the negative electrode active material, the polymer precursor material, the sodium salt and the binder in a solvent, and stirring them evenly to obtain a negative electrode slurry.

[0097] Among them, the negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; the carbon-based material is an amorphous carbon material, including hard carbon and soft carbon; the precursor of the amorphous carbon material includes but is not limited to: one or more of biomass precursors, synthetic resin precursors, and asphalt precursors; wherein the biomass precursor includes but is not limited to: one or more of coconut shells, straws, walnut shells, sugar, and starch; the synthetic resin precursor specifically includes but is not limited to: phenolic resin and / or epoxy resin; the silicon-based material includes silicon-oxygen material and / or silicon-carbon composite material; the titanium-based material includes but is not limited to: Na2Ti3O7, Li4Ti5O 12 、Na 0.66 [L i 0.22 T i 0.78 ]O2、Na 0.6 [Cr 0.6 T i 0.4 ]One or more of Na2T i OPO4, Na2T i2(PO4)3.

[0098] The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene.

[0099] Sodium salts include, but are not limited to, NaFS I and / or NaTFS I.

[0100] The mass ratio of the negative electrode active material, the polymer precursor material, the sodium salt and the binder is [50-90]: [1-30]: [0-20]: [0-10]; the mass of the polymer precursor material is the total mass of the precursor material of the in-situ generated polymer.

[0101] The solvent includes deionized water or N-methylpyrrolidone; the solid content in the negative electrode slurry is 45wt%-60wt%.

[0102] The stirring in this step can be carried out using conventional equipment to stir the material evenly in the solvent.

[0103] Step 220, coating the negative electrode slurry on one or both sides of the current collector, drying it at the polymerization temperature of the polymer precursor material, forming a polymer in situ on the surface of the current collector, and cutting or slicing to obtain a negative electrode sheet containing the coating material.

[0104] Wherein, the current collector includes copper foil or aluminum foil; the coating method of this step is a conventional known method, and the coating thickness is 10 μm-100 μm.

[0105] The polymer formed in this step is a polymer containing polar groups, and the polar groups of the polymer include: one or more groups of hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds; the polymer specifically includes: polyethylene glycol (PEG), polystyrene (P S), poly (ethylene glycol) methyl ether methacrylate (PEGMA), 1,3-dioxolane (DOL), polyethylene glycol borate, polyethylene glycol succinate (PE-2,4), poly (β-propiolactone) (PPL), poly (ethylene glycol) methyl ether acrylate (PPEGMA), polyvinyl chloride (PVC), polytrimethylene carbonate (PTMC), polypropylene carbonate (PPC), polycyanoacrylate (PECA), polyoxalate (POE), polyphosphazene (PPN), polyacrylonitrile (PAN), polysiloxane or more.

[0106] In the present invention, the negative electrode active material of the negative electrode plate is wrapped by a polymer, and the gaps between the negative electrode active materials are also filled with a polymer. The chain segments in the non-crystalline region of the polymer can flow, and the violent movement of the chain segments at a certain temperature can transport sodium ions.

[0107] In the present invention, the negative electrode plate also includes sodium salt. The alkali metal ions in the sodium salt form weak coordination with the polar groups of the polymer. The coordination bond strength is relatively weak, easy to form and easy to break. Above the glass transition temperature of the polymer, under the action of the electric field, the polymer molecules vibrate, and the sodium ions are continuously complexed and decomplexed with the polar groups on the polymer molecular segments, forming a transmission channel for the sodium ions. In addition, the sodium ion transmission path is complex, and intra-chain hopping transmission or chain-to-chain hopping transmission can be performed, which greatly improves the transmission efficiency.

[0108] The sodium salt accounts for 0-20% of the total mass percentage of the coating material, which can be any value within the above range, for example: 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The sodium salt of the present invention preferably accounts for 5% of the total mass percentage of the coating material.

[0109] The mass percentage of the polymer in the present invention to the total mass of the coating material is 1%-30%, which can be any value within the above range, for example: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc., but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The mass percentage of the polymer in the present invention to the total mass of the coating material is preferably 5%-15%, more preferably 5%.

[0110] An embodiment of the present invention provides an all-solid-state sodium ion battery, which includes a solid electrolyte membrane, a positive electrode plate, and a negative electrode plate containing a coating material prepared by the above two methods.

[0111] Among them, the positive electrode sheet is prepared by the existing conventional method. The specific process is: the positive electrode active material, other additive materials, and solvent are evenly mixed in proportion to form a positive electrode slurry, and then the positive electrode slurry is coated on one side of the current collector, and the positive electrode sheet is obtained after drying.

[0112] The positive electrode active material includes, but is not limited to, any one of phosphates, ternary materials, vanadium oxides, vanadates, transition metal oxides, Prussian blue compounds, and polyanion compounds.

[0113] The current collector for preparing the positive electrode sheet is copper foil or aluminum foil.

[0114] Other additive materials include conductive materials and binders.

[0115] Specifically, the conductive material includes: one or more of graphite conductive agent, conductive carbon black, and graphene; the graphite conductive agent includes: one or more of KS-6, KS-15, SFG-6, and SFG-15; the conductive carbon black includes: one or more of acetylene black, Super P, Super S, 350G, carbon fiber VGCF, carbon nanotubes CNTs, Ketjen black, and activated carbon.

[0116] The binder includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, carboxymethyl cellulose, sodium carboxymethyl cellulose, polymethyl methacrylate, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, polyvinyl alcohol, polytetrafluoroethylene, polyacrylamide, polyvinyl acetate or polyurethane.

[0117] In an optional scheme, the slurry preparation process of the positive electrode plate can also be the same as the preparation process of the negative electrode plate provided in the embodiment of the present invention. In the process of preparing the positive electrode slurry, a polymer containing polar groups or a polymer precursor material is added to wrap the polymer on the surface and in the gaps of the positive electrode active material, and the polar groups form a sodium ion transmission channel; the type of polymer in the positive electrode plate is the same as that in the negative electrode plate.

[0118] The solid electrolyte membrane of the above-mentioned all-solid-state sodium ion battery is prepared by one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-organic composite solid electrolyte.

[0119] Among them, the inorganic solid electrolytes include: one or more of halide-based, oxide-based solid electrolytes and their modified derivatives, LLZO and its modified derivatives, LATP and its modified derivatives, LLTO and its modified derivatives, sulfide-based solid electrolytes, boron-based solid electrolytes and their modified derivatives.

[0120] The polymer solid electrolyte includes one or more of polyethylene oxide and its modified derivatives, polycarbonate and its derivatives, polyacrylonitrile and its derivatives, polyvinyl alcohol and its derivatives, polyvinyl pyrrolidone and its derivatives, polyvinylidene fluoride and its derivatives, polypropylene oxide and its derivatives, polymethyl methacrylate and its derivatives.

[0121] Inorganic-organic composite solid electrolyte is a composite of inorganic solid electrolyte and organic solid electrolyte.

[0122] Since the all-solid-state sodium ion battery uses the negative electrode plate provided by the embodiment of the present invention, and since the surface of the negative electrode active material in the negative electrode plate is wrapped by a polymer, a transmission channel for sodium ions in the negative electrode is constructed through the process of complexation with polar groups on the polymer chain segments and then decomplexation, thereby improving the ion transmission efficiency of the negative electrode material, and ensuring the first-cycle coulomb efficiency of the all-solid-state sodium ion battery and the stable reversible cycle of the all-solid-state sodium ion battery.

[0123] In order to better understand the technical solution provided by the present invention, the preparation process and characteristics of the negative electrode sheet of the present invention are respectively described below with multiple specific examples.

[0124] The hard carbon used in the following examples and comparative examples was purchased from Kuraray Co., Ltd. If no specific experimental steps or conditions are specified in each example or comparative example, the conventional experimental steps or conditions described in the literature in the field can be used. The materials, reagents or instruments used without indicating the manufacturer are all conventional products purchased from the market.

[0125] Example 1

[0126] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0127] (1) Take 85wt% of hard carbon, 5wt% of the precursor materials of polyethylene glycol borate, boric oxide and polyethylene glycol (the molar ratio of boric oxide to polyethylene glycol is 1:3), 5wt% of NaFS I and 5wt% of CMC, a total of 100g, disperse them in deionized water, stir evenly, and obtain a negative electrode slurry with a solid content of 45wt%.

[0128] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil and dried at 110° C. for 12 hours to form polyethylene glycol borate in situ on the surface of the current collector. Then, a disc with a diameter of 8 or 12 mm was cut to obtain a negative electrode sheet containing the coating material. The surface loading of the negative electrode active material on the negative electrode sheet was 1 mg / cm 2 .

[0129] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0130] The negative electrode sheet prepared in this embodiment was assembled into an all-solid-state sodium metal battery and tested. The specific process is as follows.

[0131] The solid electrolyte membrane of the all-solid-state sodium metal battery of this embodiment is a PEO polymer electrolyte membrane. The preparation process of the solid electrolyte membrane is as follows: PEO (molecular weight Mw is 600000) and NaFS I are dissolved in acetonitrile (EO and Na + The molar ratio of 20:1 was prepared into a 0.05 g / L viscous solution, which was cast into a polytetrafluoroethylene mold and vacuum dried at 55°C for 24 hours to obtain a PEO polymer electrolyte membrane.

[0132] Assembly of the all-solid-state sodium metal battery: The negative electrode plate of this embodiment is matched with the PEO polymer electrolyte membrane and assembled into an all-solid-state sodium metal battery by conventional methods.

[0133] Test of all-solid-state sodium metal battery: In the 0-2.5V cut-off voltage window, the all-solid-state sodium metal battery of this embodiment was tested in a cycle at a current density of 0.1C at a temperature of 70°C and a first-cycle coulombic efficiency (I CE) of 86.46%, and a first-cycle reversible capacity of 279.60mAh / g.

[0134] The first cycle charge and discharge curve of the all-solid-state sodium metal battery prepared in this embodiment is as follows: Figure 4 shown.

[0135] The first cycle (1st) and fifth cycle (5th) charge-discharge curves of the all-solid-state sodium metal battery prepared in this embodiment are as follows: Figure 5 shown.

[0136] The negative electrode sheet prepared in this embodiment was assembled into an all-solid-state sodium ion battery and tested. The specific process is as follows.

[0137] The solid electrolyte membrane of the all-solid-state sodium ion battery of this embodiment adopts the same PEO polymer electrolyte membrane as the all-solid-state sodium metal battery.

[0138] The positive electrode of the all-solid-state sodium-ion battery adopts a composite phosphate positive electrode. The specific preparation process is as follows: take 40 mg of the precursor materials of polyethylene glycol borate, boron oxide and polyethylene glycol (the molar ratio of boron oxide to polyethylene glycol is 1:3), 40 mg of NaFSI, 80 mg of conductive agent Super P, 800 uL of polyvinylidene fluoride (PVDF) solution (PVDF is dissolved in NMP solvent with a concentration of 0.05 g / L) and 600 mg of sodium vanadium phosphate, degassing and stirring at a high speed of 900 r / min to form a uniform solution, and obtain a positive electrode slurry, which is evenly coated on aluminum foil with a coating thickness of 75 μm, and the electrode is dried in a blast drying oven at 80°C, and then punched into a circular electrode with a diameter of 12 mm, and dried in a vacuum drying oven at 120°C for 12 hours to obtain a composite phosphate positive electrode. Then transfer it to a vacuum glove box for standby use.

[0139] The assembly of the all-solid-state sodium ion battery is a conventional method, wherein the negative electrode plate of this embodiment is attached to one side of the above-mentioned PEO polymer electrolyte membrane, and the prepared composite phosphate positive electrode plate is attached to the other side of the PEO polymer electrolyte membrane.

[0140] The electrochemical performance test of the assembled all-solid-state sodium ion battery was conducted using a blue electric tester. Specifically, the first cycle coulomb efficiency of the all-solid-state sodium ion battery was 77.85% at a current density of 0.1C at a temperature of 70°C within a cut-off voltage window of 0-4V. The first cycle charge and discharge curve of the all-solid-state sodium ion battery assembled in this embodiment is shown in FIG. Figure 6 shown.

[0141] Example 2

[0142] This embodiment provides a preparation process and performance test of a negative electrode plate, which is different from Embodiment 2 in that polyethylene glycol borate is added non-in-situ. The specific preparation process is as follows.

[0143] (1) Take 85% of hard carbon, 5% of polyethylene glycol borate, 5wt% of NaFS I and 5wt% of CMC, a total of 100g, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45wt%.

[0144] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm, and then vacuum dried at 120°C for 24 hours to obtain a negative electrode sheet containing the coating material, wherein the negative electrode active material surface loading on the negative electrode sheet was 1 mg / cm 2 .

[0145] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium metal battery and tested. The assembly process and the testing process are the same as those in Example 1. The first-cycle coulombic efficiency (I CE) of the all-solid-state sodium metal battery in this embodiment is 89.75%, and the first-cycle reversible capacity is 281.31 mAh / g.

[0146] The charge-discharge curves of the first and fifth cycles of the all-solid-state sodium metal battery assembled in this embodiment are as follows: Figure 7 shown.

[0147] Example 3

[0148] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0149] (1) Take 100 g of 85 wt % of hard carbon, 5 wt % of polyurethane, 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0150] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm, and then vacuum dried at 120°C for 24 hours to obtain a negative electrode sheet containing the coating material. The negative electrode active material surface loading on the negative electrode sheet was 1 mg / cm 2 .

[0151] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0152] The negative electrode plates prepared using the embodiments of the present invention are assembled into all-solid-state sodium metal batteries and all-solid-state sodium ion batteries, and the battery assembly process is the same as that in Embodiment 1.

[0153] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion batteries are within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed.

[0154] Example 4

[0155] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0156] (1) Take 85 wt % of hard carbon, 5 wt % of polysiloxane, 5 wt % of NaFS I and 5 wt % of CMC, a total of 100 g, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0157] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into two discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain two negative electrode sheets containing the coating material. The negative electrode active material surface loading on the negative electrode sheet was 1 mg / cm 2 .

[0158] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0159] The negative electrode sheet prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery, and the battery assembly process is the same as that of Example 1.

[0160] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that polysiloxane is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the other processes are the same as Example 1.

[0161] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed. This is because the introduction of silicon-oxygen bonds improves the sodium ion transmission efficiency of the electrode material, and at the same time greatly improves the reduction resistance of the hard carbon material on the negative electrode side, reduces the occurrence of side reactions on the negative electrode side of the battery, ensures battery circulation and improves battery efficiency.

[0162] Example 5

[0163] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0164] (1) Take 100 g of 85 wt % of hard carbon, 5 wt % of polyethylene glycol (PEG), 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0165] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into two discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain two negative electrode sheets containing the coating material. The negative electrode active material surface loading on the negative electrode sheet was 1 mg / cm2 .

[0166] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0167] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0168] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 2 in that PEG is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane also uses a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0169] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed. This is because the introduction of ether oxygen bonds improves the sodium ion transmission efficiency of the electrode material, and at the same time greatly improves the reduction resistance of the hard carbon material on the negative electrode side, reduces the occurrence of side reactions on the negative electrode side of the battery, ensures battery circulation and improves battery efficiency.

[0170] Example 6

[0171] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0172] (1) Take 100 g of 85 wt % of hard carbon, 5 wt % of polystyrene (PS), 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0173] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing the coating material. The surface loading of the negative electrode active material on the negative electrode sheet was 1 mg / cm 2 .

[0174] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0175] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 2 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0176] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery. The difference from Example 1 is that PS is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane also uses a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix). The other processes are the same as in Example 1.

[0177] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window, and the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C ensure the reversible cycle of these two batteries. This is because the introduction of silicon-oxygen bonds improves the sodium ion transmission efficiency of the electrode material, and at the same time greatly improves the reduction resistance of the hard carbon material on the negative electrode side, reduces the occurrence of side reactions on the negative electrode side of the battery, ensures the battery cycle and improves the battery efficiency.

[0178] Example 7

[0179] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0180] (1) Take 86 wt % of hard carbon, 4 wt % of poly(ethylene glycol) methyl ether methacrylate (PEGMA), 5 wt % of NaFS I and 5 wt % of CMC, a total of 100 g, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0181] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into two discs with a diameter of 12 mm. The discs were then vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing a coating material. The surface loading of the coating material on the negative electrode sheet was 2 mg / cm 2 .

[0182] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0183] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0184] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that PEGMA is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0185] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window, and the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C can ensure the reversible cycle of these two batteries. This is because the introduction of ether oxygen bonds improves the sodium ion transmission efficiency of the electrode material, and at the same time greatly improves the reduction resistance of the hard carbon material on the negative electrode side, reduces the occurrence of side reactions on the negative electrode side of the battery, ensures the battery cycle and improves the battery efficiency.

[0186] Example 8

[0187] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0188] (1) Take 100 g of 88 wt % of hard carbon, 2 wt % of 1,3-dioxolane (DOL), 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0189] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing the coating material. The surface loading of the negative electrode active material on the negative electrode sheet was 1 mg / cm 2 .

[0190] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0191] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0192] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that DOL is used instead of polyethylene oxide ether in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0193] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed. This is because the introduction of ether oxygen bonds improves the sodium ion transmission efficiency of the electrode material, and at the same time greatly improves the reduction resistance of the hard carbon material on the negative electrode side, reduces the occurrence of side reactions on the negative electrode side of the battery, ensures battery circulation and improves battery efficiency.

[0194] Example 9

[0195] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0196] (1) Take 84 wt % of hard carbon, 6 wt % of polyethylene glycol succinate, 5 wt % of NaFS I and 5 wt % of CMC, a total of 100 g, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0197] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain negative electrode sheets containing the coating material. The negative electrode active material surface loading on the negative electrode sheet was 2 mg / cm 2 .

[0198] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0199] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0200] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that polyethylene glycol succinate is used instead of polyethylene oxide ether in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0201] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion batteries are within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed.

[0202] Example 10

[0203] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0204] (1) Take 100 g of 83 wt % of hard carbon, 7 wt % of poly(β-propiolactone), 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0205] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing a coating material. The surface loading of the coating material on the negative electrode sheet was 2 mg / cm 2 .

[0206] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0207] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0208] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 2 in that the preparation process of the composite phosphate positive electrode plate uses poly(β-propiolactone) instead of polyethylene oxide ether, and the solid electrolyte membrane uses a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0209] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cutoff voltage window, and the all-solid-state sodium ion battery is within the 0-4V cutoff voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries can be guaranteed.

[0210] Embodiment 11

[0211] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0212] (1) Take 100 g of 82 wt % of hard carbon, 8 wt % of polytrimethylene carbonate, 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0213] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing a coating material. The surface loading of the coating material on the negative electrode sheet was 2 mg / cm 2 .

[0214] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0215] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0216] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that polytrimethylene carbonate is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1 wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0217] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries is guaranteed.

[0218] Example 12

[0219] This embodiment provides a preparation process and performance test of a negative electrode plate, and the specific preparation process is as follows.

[0220] (1) Take 100 g of 85 wt % of hard carbon, 5 wt % of polyacrylonitrile, 5 wt % of NaFS I and 5 wt % of CMC, disperse them in deionized water, and stir them evenly to obtain a negative electrode slurry with a solid content of 45 wt %.

[0221] (2) The negative electrode slurry was coated on the surface of one side of the current collector copper foil, dried at 80°C for 40 minutes, and then cut into discs with a diameter of 12 mm. Then, the discs were vacuum dried at 120°C for 12 hours to obtain a negative electrode sheet containing the coating material. The active material surface loading on the negative electrode sheet was 1 mg / cm 2 .

[0222] The prepared negative electrode sheet was transferred to a vacuum glove box for later use.

[0223] The negative electrode plate prepared by the embodiment of the present invention is assembled into an all-solid-state sodium metal battery. The difference from Example 1 is that the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into a PEO matrix), and the battery assembly process is the same as that of Example 1.

[0224] The negative electrode plate prepared in this embodiment is assembled into an all-solid-state sodium ion battery, which is different from Example 1 in that polyacrylonitrile is used instead of polyethylene oxide in the preparation process of the composite phosphate positive electrode plate, and the solid electrolyte membrane adopts a composite of an inorganic solid electrolyte and an organic solid electrolyte (specifically, 1wt% Na-β-Al2O3 composite electrolyte is introduced into the PEO matrix), and the other processes are the same as Example 1.

[0225] The all-solid-state sodium metal battery assembled in this embodiment is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at a current density of 0.1C at 70°C, the reversible cycle of these two batteries is guaranteed.

[0226] Embodiment 13

[0227] This embodiment provides a preparation process and performance test of a negative electrode plate, which is different from Example 1 in that the negative electrode active material used is silicon dioxide, and the other preparation processes are the same as those of Example 1. The process of assembling the all-solid-state sodium metal battery in this embodiment is the same as that in Example 1. The all-solid-state sodium metal battery is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at 0.1C current density at 70°C, the reversible cycle of the two batteries can be guaranteed.

[0228] Embodiment 14

[0229] This embodiment provides a preparation process and performance test of a negative electrode plate, which is different from Example 12 in that the negative electrode active material used is Na2Ti3O7, and the other preparation processes are the same as those of Example 12. The process of assembling the all-solid-state sodium metal battery in this embodiment is the same as that in Example 12. The all-solid-state sodium metal battery is within the 0-2.5V cut-off voltage window, and the all-solid-state sodium ion battery is within the 0-4V cut-off voltage window. Under the test conditions of 0.5C long cycle after 5 cycles at 0.1C current density at 70°C, the reversible cycle of the two batteries can be guaranteed.

[0230] In order to better illustrate the effect of the embodiment of the present invention, comparative example 1 is compared with the above embodiment.

[0231] Comparative Example 1

[0232] This comparative example is different from the embodiment in that no sodium salt and polymer are added in the process of preparing the negative electrode slurry. The negative electrode slurry is obtained by dispersing 100g of 95wt% hard carbon and 5wt% CMC in deionized water and stirring evenly. The other negative electrode sheet preparation and all-solid-state sodium metal battery assembly process and testing process are the same as Example 1.

[0233] The first cycle coulombic efficiency (I CE) of the all-solid-state sodium metal battery in this comparative example is 86.10%, and the first cycle reversible capacity is 198.84 mAh / g. It can be seen that the first cycle coulombic efficiency and the first cycle reversible capacity of the all-solid-state sodium metal battery in this comparative example are both smaller than those of the all-solid-state sodium metal battery in the embodiment. The first cycle charge and discharge curve of the all-solid-state sodium metal battery in this comparative example is shown in FIG. Figure 8 shown.

[0234] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A negative electrode sheet, It is characterized in that The negative electrode plate includes: a current collector, and a coating material attached to one side or both sides of the current collector; The coating material comprises: a negative electrode active material, and a polymer coated on the particle surface of the negative electrode active material and filled in the particle gap of the negative electrode active material; The polymer is obtained in situ or ex situ on the negative electrode sheet; The polymer has polar groups on its molecular chain segments; The negative electrode plate is used in an all-solid-state sodium ion battery. When the operating temperature of the all-solid-state sodium ion battery is greater than or equal to the glass transition temperature of the polymer, when the all-solid-state sodium ion battery performs a charge and discharge cycle, the sodium ions in the negative electrode plate and the polar groups on the molecular chain segments of the polymer undergo a complexation and decomplexation process along the molecular chain segments, so that the sodium ions are transported along the molecular chain segments to form a sodium ion transmission channel.

2. The negative electrode sheet according to claim 1, It is characterized in that The negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; the mass of the negative electrode active material accounts for 50%-99% of the total mass of the coating material; The polar groups of the polymer include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, mercapto groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds; the mass of the polymer accounts for 1%-30% of the total mass of the coating material; The current collector includes copper foil or aluminum foil.

3. The negative electrode sheet according to claim 2, It is characterized in that The carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the silicon-based material includes a silicon-oxygen material and / or a silicon-carbon composite material; The titanium-based material includes: Na 2 Ti 3 O 7 , Li 4 Ti 5 O 12 、Na 0.66 [Li 0.22 Ti 0.78 ]O 2 、Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 、Na 2 TiOPO 4 、Na 2 Ti 2 (PO 4 ) 3 One or more of; The polymer specifically includes: one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane.

4. The negative electrode sheet according to claim 1, It is characterized in that The coating material also includes a binder and a sodium salt; The binder comprises: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxymethyl cellulose, polyacrylic acid, polytetrafluoroethylene, and sodium alginate; the binder accounts for 0-10% of the total mass percentage of the coating material; The coating material further comprises sodium salt; the sodium salt comprises: NaFSI and / or NaTFSI; the sodium salt accounts for 0-20% of the total mass percentage of the coating material.

5. A method for preparing the negative electrode sheet according to any one of claims 1 to 4, It is characterized in that The preparation method comprises: Adding negative electrode active material, polymer, sodium salt and binder into solvent and stirring evenly to obtain negative electrode slurry; The negative electrode slurry is coated on one side or both sides of the current collector, and after drying, it is cut or sliced, and then vacuum dried to obtain a negative electrode sheet containing the coating material; The polymer is a polymer containing polar groups; wherein the polar groups include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, carbamoyl groups and their derivatives, amide groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds.

6. The preparation method according to claim 5, It is characterized in that The negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; wherein, the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the silicon-based material includes silicon-oxygen materials and / or silicon-carbon composite materials; the titanium-based material includes: Na 2 Ti 3 O 7 , Li 4 Ti 5 O 12 、Na 0.66 [Li 0.22 Ti 0.78 ]O 2 、Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 、Na 2 TiOPO 4 、Na 2 Ti 2 (PO 4 ) 3 One or more of; The polymer includes one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane; The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene; The sodium salt includes: NaFS I and / or NaTFS I; The mass ratio of the negative electrode active material, polymer, sodium salt and binder is [50-90]: [1-30]：[0-20]：[0-10]； The solvent includes deionized water or N-methylpyrrolidone; The current collector comprises copper foil or aluminum foil; The drying temperature is 80°C-100°C, and the drying time is 40 minutes-8 hours; The vacuum drying temperature is 120° C., and the vacuum drying time is 10 hours to 15 hours.

7. A method for preparing the negative electrode sheet according to any one of claims 1 to 4, It is characterized in that The preparation method comprises: Dissolving the negative electrode active material, the polymer precursor material, the sodium salt and the binder in a solvent, and stirring evenly to obtain a negative electrode slurry; The negative electrode slurry is coated on one side of the current collector, and dried at the polymerization temperature of the polymer precursor material to form a polymer in situ on the surface of the current collector, and the negative electrode sheet containing the coating material is obtained by cutting or slicing; The polymer is a polymer containing polar groups; wherein the polar groups include: one or more groups selected from hydrocarbon groups and their derivatives, carboxyl groups and their derivatives, sulfonic acid groups and their derivatives, ester groups and their derivatives, haloformyl groups and their derivatives, amide groups and their derivatives, carbamoyl groups and their derivatives, cyano groups and their derivatives, aldehyde groups and their derivatives, hydroxyl groups and their derivatives, alcoholic hydroxyl groups and their derivatives, phenolic hydroxyl groups and their derivatives, thiol groups and their derivatives, amino groups and their derivatives, and silicon-oxygen bonds.

8. The preparation method according to claim 7, It is characterized in that The negative electrode active material includes: one or more of carbon-based materials, silicon-based materials, titanium-based materials, metal oxide negative electrode materials, and alloy materials; wherein the carbon-based material is an amorphous carbon material, including hard carbon or soft carbon; the silicon-based material includes silicon-oxygen materials and / or silicon-carbon composite materials; the titanium-based material includes: Na 2 Ti 3 O 7 , Li 4 Ti 5 O 12 、Na 0.66 [Li 0.22 Ti 0.78 ]O 2 、Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 、Na 2 Ti OPO 4 、Na 2 Ti 2 (PO 4 ) 3 One or more of; The polymer specifically includes: one or more of polyethylene glycol, polystyrene, poly(ethylene glycol) methyl ether methacrylate, 1,3-dioxolane, polyethylene glycol borate, polyethylene glycol succinate, poly(β-propiolactone), poly(ethylene glycol) methyl ether acrylate, polyvinyl chloride, polytrimethylene carbonate, polypropylene carbonate, polynitrile acrylate, polyoxalate, polyphosphazene, polyacrylonitrile, and polysiloxane; The sodium salt includes: NaFS I and / or NaTFS I; The binder includes: one or more of polyvinylidene fluoride, polyvinyl alcohol, polyacrylamide, sodium hydroxyethyl cellulose, polyacrylamide, and polytetrafluoroethylene; The mass ratio of the negative electrode active material, the polymer precursor material, the sodium salt and the binder is [50-90]: [1-30]: [0-20]: [0-10]; The solvent includes deionized water or N-methylpyrrolidone; The current collector includes copper foil or aluminum foil.

9. An all-solid-state sodium-ion battery, It is characterized in that The all-solid-state sodium ion battery comprises a positive electrode plate, a solid electrolyte membrane and a negative electrode plate as described in any one of claims 1 to 4 above.

10. The all-solid-state sodium ion battery according to claim 9, It is characterized in that The solid electrolyte membrane is prepared by one or more of an inorganic solid electrolyte, a polymer solid electrolyte, and an inorganic-organic composite solid electrolyte; The positive electrode active material of the positive electrode plate includes any one of phosphates, ternary materials, vanadium oxides, vanadates, transition metal oxides, Prussian blue compounds, and polyanion compounds.

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