Sodium supplement material and preparation method thereof, positive electrode sheet, and sodium ion battery

Abstract

This application provides a sodium-replenishing material and its preparation method, a positive electrode sheet, and a sodium-ion battery, wherein the sodium-replenishing material includes a sodium-replenishing agent Na. x C y O z H w For the metal oxide catalyst, 1≤x≤3, 1≤y≤6, 1≤z≤7, 0≤w≤5; the first EDS test is performed on any first region on the surface of the sodium-supplementing material, and the content of the metal element belonging to the metal oxide catalyst is measured to be C0. The second EDS test is performed on the first region after melting, and the content of the metal element belonging to the metal oxide catalyst is measured to be C1, where C1>C0.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a sodium-supplementing material and its preparation method, a positive electrode sheet, and a sodium-ion battery. Background Technology

[0002] Sodium-ion batteries, with their advantages of low cost, abundant sodium resources, and relatively high energy density, are expected to replace traditional lithium-ion batteries in the field of energy storage.

[0003] Adding sodium to the positive electrode using a sodium-replenishing agent can reduce the adverse effects of sodium loss on the electrochemical performance of sodium-ion batteries. However, existing sodium-replenishing agents still suffer from high oxidation decomposition potentials, limiting their actual sodium replenishment effect in sodium-ion batteries, and thus, the performance of sodium-ion batteries needs further improvement. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a sodium-supplementing material and its preparation method, a positive electrode sheet, and a sodium-ion battery, in order to improve the performance of sodium-ion batteries.

[0005] In the first aspect, this application provides a sodium supplement material, including sodium supplement agent Na. x C y O z H w The metal oxide catalyst has the following properties: 1≤x≤3, 1≤y≤6, 1≤z≤7, 0≤w≤5. A first EDS test is performed on any first region on the surface of the sodium-supplementing material, and the content of the metal element belonging to the metal oxide catalyst is measured to be C0. A second EDS test is performed on the first region after melting, and the content of the metal element belonging to the metal oxide catalyst is measured to be C1, where C1>C0.

[0006] In some embodiments of this application, the sodium-supplementing material has a composite structure in which the sodium-supplementing agent coats the metal oxide catalyst.

[0007] In some embodiments of this application, the oxidative decomposition potential of the sodium-supplementing material is E. pa 4.10V≤E pa ≤4.20V.

[0008] In some embodiments of this application, the D50 of the sodium-supplementing material is 0.8 μm to 2 μm.

[0009] In some embodiments of this application, the sodium supplement agent has a mass percentage content of 70% to 95% based on the mass of the sodium supplement material, and the metal oxide catalyst has a mass percentage content of 5% to 30%.

[0010] In some embodiments of this application, the sodium supplement is selected from at least one of CH3COONa, C6H5Na3O7, Na2C4O4, Na2CO3, Na2C2O4, and Na2C6O6.

[0011] In some embodiments of this application, the metal oxide catalyst is selected from at least one of titanium dioxide, ruthenium dioxide, manganese dioxide, molybdenum dioxide, cobalt tetroxide, iron tetroxide, and tin dioxide.

[0012] Secondly, this application provides a method for preparing the sodium-supplementing material as described in the first aspect, comprising the following steps:

[0013] The sodium supplement agent after particle size control treatment was mixed with an alcohol-based solvent to obtain a dispersion, wherein the D50 of the sodium supplement agent after particle size control treatment was 1 μm to 3 μm.

[0014] The catalyst precursor was added to the dispersion and mixed, and then dried to obtain a mixture;

[0015] The mixture is calcined in a gaseous atmosphere at a temperature of 300℃ to 500℃ for 1 to 6 hours to obtain the sodium-supplementing material.

[0016] In some embodiments of this application, the method further includes:

[0017] The particle size distribution of the sodium supplement is controlled by recrystallization, ball milling, crushing, or spray drying to obtain the sodium supplement after particle size control treatment.

[0018] In some embodiments of this application, the catalyst precursor is selected from at least one of tetrabutyl titanate, manganese diethylhexanoate, iron diethylhexanoate, copper diethylhexanoate, cobalt 2-ethylhexanoate, nickel diethylhexanoate, and stannous diethylhexanoate.

[0019] In some embodiments of this application, the alcohol-based solvent is selected from at least one of methanol, ethanol, and ethylene glycol.

[0020] In some embodiments of this application, the gas atmosphere includes any one of argon, nitrogen, and air.

[0021] Thirdly, this application provides a positive electrode sheet, including a current collector and a positive electrode active material layer disposed on at least one surface of the current collector, wherein the positive electrode active material layer includes a sodium-supplementing material as described in the first aspect, or includes a sodium-supplementing material prepared by the preparation method described in the second aspect.

[0022] Fourthly, this application provides a sodium-ion battery, the sodium-ion battery comprising the positive electrode sheet described in the third aspect.

[0023] Fifthly, this application provides a battery pack including a housing and at least one sodium-ion battery as described in the fourth aspect, the sodium-ion battery being housed within the housing.

[0024] In a sixth aspect, this application provides an electrical device including the sodium-ion battery described in the fourth aspect or the battery pack described in the fifth aspect.

[0025] Compared with the prior art, this application has at least the following beneficial effects:

[0026] This application provides a sodium-supplementing material and its preparation method, a positive electrode sheet, and a sodium-ion battery. The sodium-supplementing material includes a sodium-supplementing agent, Na. x C y O z H w A first EDS (Energy Dispersive X-ray Spectroscopy) test was performed on any first region of the sodium-replenishing material surface, along with a metal oxide catalyst. The content of the metal element belonging to the metal oxide catalyst was determined to be C0. A second EDS test was performed on the molten first region, and the content of the metal element belonging to the metal oxide catalyst was determined to be C1, where C1 > C0. Sodium-replenishing materials with the above characteristics are conducive to electron transfer, resulting in a low oxidation decomposition potential, thereby improving the initial sodium replenishment effect and enhancing the energy density and cycle performance of sodium-ion batteries. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a residential energy storage system according to one embodiment of this application;

[0029] Figure 2 This is a schematic diagram of the structure of an energy storage system according to one embodiment of this application;

[0030] Figure 3 The image shows a scanning electron microscope (SEM) image of the sodium supplement material prepared in Example 1.

[0031] Figure 4 SEM image of the sodium supplement material prepared in Comparative Example 4;

[0032] Figure 5The dQ / dV differential capacity curve is shown for the first charge cycle of the first coin cell in Example 1.

[0033] Figure 6 The dQ / dV differential capacity curve is shown for the first charge cycle of the first coin cell in Comparative Example 1.

[0034] Figure 7 The first charge-discharge curve of the second coin cell in Example 1;

[0035] Figure 8 The first charge-discharge curve of the second coin cell in Comparative Example 3 is shown.

[0036] Explanation of reference numerals in the attached drawings: 1-Energy storage device, 2-Power conversion device, 3-First user load, 4-Second user load, 400-Energy storage system, 410-High voltage cable, 420-First power conversion device, 430-Second power conversion device. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0039] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0040] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0041] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0042] This application provides a sodium supplement material, which includes a sodium supplement agent Na. x C y O z H w The sodium-replenishing material contains a metal oxide catalyst, wherein 1≤x≤3, 1≤y≤6, 1≤z≤7, and 0≤w≤5. A first EDS test is performed on any first region on the surface of the sodium-replenishing material, and the content of the metal element belonging to the metal oxide catalyst is measured to be C0. A second EDS test is performed on the molten first region, and the content of the metal element belonging to the metal oxide catalyst is measured to be C1, where C1 > C0. The sodium-replenishing material of this application possesses the above characteristics, indicating that after melting, more of the exposed metal oxide catalyst is exposed. This indicates that the metal oxide catalyst in the sodium-replenishing material is effectively coated by the sodium-replenishing agent. This coating structure facilitates electron transfer, resulting in a low oxidation decomposition potential and thus improving the initial sodium-replenishing effect. The sodium-replenishing material of this application can release additional sodium ions during the first charge cycle of a sodium-ion battery, thereby compensating for sodium ion loss caused by SEI film formation at the negative electrode and other side reactions, improving the energy density and cycle performance of the sodium-ion battery.

[0043] In this application, the first region can be any pre-selected region on the surface of the sodium-supplementing material. For example, the first region can be a rectangular region of 500nm × 500nm, or a region with an area of ​​0.25μm. 2 ~1μm 2The first region is a circular area. After the first EDS test, the first region can be heat-treated for 5 to 10 minutes to melt the sodium-supplementing material in the first region, and then a second EDS test can be performed on the melted first region. This application does not have any particular limitation on the heat treatment method, as long as it can melt the sodium-supplementing material. For example, the first region can be heat-treated by using a SEM device at an accelerating voltage of 10 kV or 20 kV.

[0044] Understandably, EDS testing allows for the quantitative analysis of the content of various elements in sodium-supplementing materials, such as the metal element content of metal oxide catalysts. In one example, if the metal oxide catalyst is titanium dioxide (TiO2), the titanium content can be obtained after the first EDS test, denoted as C0, and after the second EDS test, it can be obtained as C1.

[0045] In some embodiments of this application, the sodium-supplementing material has a composite structure in which the sodium-supplementing agent is coated with a metal oxide catalyst. This composite structure facilitates electron transfer, resulting in a low oxidation decomposition potential and thus improving the initial sodium-supplementing effect. This allows the sodium-supplementing material to release additional sodium ions during the first charge cycle of the sodium-ion battery, thereby increasing the energy density and cycle performance of the sodium-ion battery.

[0046] In some embodiments of this application, the oxidative decomposition potential of the sodium-supplementing material is E. pa 4.10V≤E pa The oxidation decomposition potential is ≤4.20V, for example, 4.10V, 4.12V, 4.14V, 4.15V, 4.16V, or 4.20V. The sodium replenishment material of this application has a lower oxidation decomposition potential than existing sodium replenishment materials, which can improve the sodium replenishment effect in the first cycle, reduce the irreversible capacity loss in the first cycle of sodium-ion batteries, and thus improve the coulombic efficiency of sodium-ion batteries in the first cycle.

[0047] In this application, the oxidation decomposition potential refers to the potential corresponding to the oxidation decomposition reaction that occurs when the sodium supplement material undergoes an oxidation decomposition reaction during the charging process.

[0048] In some embodiments of this application, the D50 of the sodium-supplementing material is 0.8 μm to 2 μm, for example, D50 is 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, or 2 μm. By controlling the D50 of the sodium-supplementing material within the above range, the electron transport distance between the sodium-supplementing material particles can be effectively shortened, thereby promoting the oxidative decomposition process of the sodium supplement and facilitating the reduction of the oxidative decomposition potential of the sodium-supplementing material.

[0049] In some embodiments of this application, based on the mass of the sodium-supplementing material, the mass percentage of the sodium-supplementing agent is 70%–95%, and the mass percentage of the metal oxide catalyst is 5%–30%. For example, the mass percentage of the sodium-supplementing agent is 70%, 75%, 80%, 85%, 90%, or 95%; and the mass percentage of the metal oxide catalyst is 5%, 10%, 15%, 20%, 25%, or 30%. By controlling the mass ratio of the sodium-supplementing agent to the metal oxide catalyst in the sodium-supplementing material within the above ranges, wherein the content of the sodium-supplementing agent is higher than the content of the metal oxide catalyst, it is beneficial to form a composite structure in which the sodium-supplementing agent coats the metal oxide catalyst.

[0050] In some embodiments of this application, the sodium supplement is selected from at least one of CH3COONa, C6H5Na3O7, Na2C4O4, Na2CO3, Na2C2O4, and Na2C6O6. The above-mentioned sodium supplements have the advantages of being environmentally friendly, widely available, and safe and non-toxic.

[0051] In some embodiments of this application, the metal oxide catalyst is selected from at least one of titanium dioxide, ruthenium dioxide, manganese dioxide, molybdenum dioxide, cobalt tetroxide, iron tetroxide, and tin dioxide. These metal oxides can act as electron acceptors, which is beneficial for forming a composite structure of a sodium-supplemented metal oxide catalyst.

[0052] Secondly, this application provides a method for preparing the sodium-supplementing material as described in the first aspect, comprising the following steps:

[0053] Preparation of dispersion: The sodium supplement agent after particle size control treatment is mixed with an alcohol-based solvent to obtain a dispersion, wherein the D50 of the sodium supplement agent after particle size control treatment is 1μm~3μm;

[0054] Preparation of the mixture: The catalyst precursor was added to the dispersion and mixed, and then dried to obtain the mixture;

[0055] Preparation of sodium supplement material: The mixture is calcined in a gas atmosphere at a temperature of 300℃~500℃ for 1h~6h to obtain sodium supplement material.

[0056] In the dispersion preparation step, the sodium supplementer can be obtained within the aforementioned particle size range by controlling its particle size. The inventors discovered that as the particle size of the sodium supplementer decreases, its specific surface area increases. In the subsequent mixture preparation process, the dispersion formed after the catalyst precursor dissolves in the alcohol-based solvent can be more uniformly distributed on the surface of the sodium supplementer. Further research revealed that the uniformity of the mixing between the catalyst precursor and the sodium supplementer affects the uniformity of the coating structure of the sodium supplement material obtained after calcination. Based on this, this application uses a sodium supplementer with controlled particle size to prepare the sodium supplement material, which can make the coating structure of the sodium supplement material more uniform, thereby improving the catalytic efficiency of the metal oxide catalyst in the sodium supplement material and reducing the oxidative decomposition potential of the sodium supplement material.

[0057] In the preparation step of the mixture, using a catalyst precursor instead of directly using a metal oxide catalyst enables the sodium supplementer and the catalyst precursor to be mixed uniformly at the nanoscale, which is beneficial to make the coating structure of the sodium supplement material more uniform.

[0058] In the preparation of the sodium-supplementing material, the calcination process of this application, that is, by controlling the calcination temperature and calcination time within the above-mentioned range, can introduce the transition metal oxides generated during the thermal decomposition of metal alkoxides into the sodium-supplementing agent. At the same time, the catalyst precursor undergoes a thermal decomposition reaction to form transition metal oxides, and other components generated by thermal decomposition (such as small organic molecules, carbon monoxide, carbon dioxide, and water) are vaporized and discharged. Furthermore, the sodium-supplementing agent melts at this temperature, and the metal oxide catalyst is uniformly dispersed in the molten sodium-supplementing agent, thereby achieving uniform coating of the metal oxide catalyst by the sodium-supplementing agent, thus forming a composite structure of sodium-supplementing agent-coated metal oxide catalyst that is conducive to electron transfer.

[0059] In the preparation of sodium supplement materials, the product obtained after calcination can be crushed by a crusher and then sieved to obtain sodium supplement materials with the required particle size range.

[0060] In some embodiments of this application, the method for preparing the sodium supplement material further includes:

[0061] The particle size distribution of sodium supplements can be controlled by recrystallization, ball milling, crushing, or spray drying to obtain sodium supplements with particle size control.

[0062] This application describes a process that reduces the particle size of sodium supplements through recrystallization, ball milling, crushing, or spray drying. The inventors have discovered that commercially available sodium supplements often have a large particle size, and recrystallization can effectively reduce this particle size. For example, when using recrystallization to control the particle size of sodium supplements, the following steps can be followed:

[0063] Add commercially available sodium supplement powder to deionized water, stir until the sodium supplement is completely dissolved, and obtain a nearly saturated sodium supplement solution.

[0064] Anhydrous ethanol was added to the sodium supplement solution, and a precipitate was formed after stirring.

[0065] The precipitate was filtered and washed with anhydrous ethanol, and then vacuum dried at 110℃~130℃ for 24h~36h to obtain recrystallized sodium supplement material. After sieving, sodium supplement material with the required particle size was obtained.

[0066] In some embodiments of this application, the catalyst precursor is selected from at least one of tetrabutyl titanate, manganese diethylhexanoate, iron diethylhexanoate, copper diethylhexanoate, cobalt 2-ethylhexanoate, nickel diethylhexanoate, and stannous diethylhexanoate. The aforementioned catalyst precursor contains a transition metal element or a post-transition metal element, enabling the introduction of transition metal oxides generated during the thermal decomposition of organometallic salts into the sodium supplement in subsequent preparation steps, forming a composite structure of sodium supplement coated metal oxide catalyst that facilitates electron transfer.

[0067] In some embodiments of this application, the alcohol-based solvent is selected from at least one of methanol, ethanol, and ethylene glycol, which is beneficial for the dissolution of the catalyst precursor.

[0068] This application does not impose any particular restrictions on the gas atmosphere during calcination, as long as it achieves the purpose of this application. In some embodiments of this application, the gas atmosphere includes any one of argon, nitrogen, and air.

[0069] The method for preparing sodium-supplementing materials provided in this application is based on the calcination of sodium-supplementing agents with particle size controlled treatment and catalyst precursors. This method can make the coating structure of the sodium-supplementing materials more uniform, which is beneficial to obtaining sodium-supplementing materials with better sodium-supplementing performance. Furthermore, the preparation method of this application is simple, and the prepared sodium-supplementing materials have excellent sodium-supplementing performance and low cost, thereby improving the energy density and cycle performance of sodium-ion batteries while reducing the production cost of sodium-ion batteries.

[0070] This application also provides a positive electrode sheet, including a current collector and a positive electrode active material layer disposed on at least one surface of the current collector. The positive electrode active material layer includes the sodium-supplementing material described in any of the above embodiments, or includes the sodium-supplementing material prepared by the preparation method described in any of the above embodiments.

[0071] The positive electrode active material layer of this application can be disposed on one or both surfaces of the positive electrode current collector in the thickness direction. In this application, the positive electrode active material layer is disposed on the surface of the positive electrode current collector; that is, the positive electrode active material layer can be disposed on a portion of one surface of the positive electrode current collector, or it can be disposed on the entire surface of one surface of the positive electrode current collector. This application does not have any particular limitation on the positive electrode current collector, as long as it can achieve the purpose of this application; for example, it can be, but is not limited to, aluminum foil, aluminum alloy foil, or composite current collectors. In this application, there is no particular limitation on the thickness of the positive electrode current collector, as long as it can achieve the purpose of this application; for example, a thickness of 8 μm to 13 μm. The thickness of the positive electrode active material layer in this application can be 150 μm to 400 μm.

[0072] In this application, the positive electrode active material layer also includes a positive electrode active material. This application does not have any particular restrictions on the positive electrode active material, as long as it can achieve the purpose of this application. For example, it may include at least one of sodium nickel manganate, sodium nickel iron manganate, sodium iron sulfate, sodium vanadium phosphate, sodium copper iron manganate, sodium iron pyrophosphate, and sodium iron pyrophosphate.

[0073] In this application, the positive electrode active material layer may further include a positive electrode conductive agent. This application does not impose any particular limitation on the positive electrode conductive agent, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of conductive carbon black (SuperP), carbon nanotubes (CNT), Ketjen black (KB), graphene, graphene oxide, and acetylene black. The mass percentage of the conductive agent in the positive electrode active material layer is 10% to 40%. In this application, the positive electrode active material layer may further include a positive electrode binder. This application does not impose any particular limitation on the positive electrode binder, as long as it can achieve the purpose of this application. For example, it may include, but is not limited to, at least one of fluorinated resin, polypropylene resin, fiber-type binder, rubber-type binder, polyimide-type binder, and polyvinylidene fluoride (PVDF).

[0074] This application also provides a sodium-ion battery, including the positive electrode sheet described in any of the above embodiments.

[0075] The sodium-ion battery of this application also includes a negative electrode, a separator, and an electrolyte, wherein the separator is located between the positive electrode and the negative electrode and plays a role in isolation.

[0076] This application does not impose any particular limitation on the negative electrode sheet, as long as it achieves the purpose of this application. For example, the negative electrode sheet typically includes a negative current collector and a negative active material layer. The negative active material layer can be disposed on the surface of the negative current collector; that is, the negative active material layer can be disposed on a portion of the surface of the negative current collector, or it can be disposed on the entire surface of the negative current collector. This application does not impose any particular limitation on the negative current collector, as long as it achieves the purpose of this application. For example, it can include, but is not limited to, copper foil, copper alloy foil, nickel foil, or composite current collectors. In this application, there is no particular limitation on the thickness of the negative current collector, as long as it achieves the purpose of this application, for example, a thickness of 4 μm to 12 μm. The thickness of the negative material layer in this application can be 70 μm to 200 μm.

[0077] In this application, the negative electrode active material layer may also include a negative electrode binder. This application does not impose any particular limitation on the negative electrode binder, as long as it can achieve the purpose of this application. For example, it may include at least one of acrylate, polyamide, polyimide, polyamide-imide, polyvinylidene fluoride, styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

[0078] In some embodiments, the diaphragm material can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The diaphragm can be a single-layer film or a multi-layer composite film, without particular limitation. When the diaphragm is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0079] The sodium-ion battery of this application also includes an electrolyte. This application does not impose any particular limitation on the electrolyte; those skilled in the art can choose according to actual needs, as long as the purpose of this application is achieved. For example, at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate (VC), or fluoroethylene carbonate (FEC) can be mixed in a certain mass or volume ratio to obtain a non-aqueous organic solvent, and then a sodium salt can be added to dissolve and mix evenly. This application does not limit the type of sodium salt, as long as the purpose of this application is achieved. For example, the sodium salt may include at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, and sodium p-toluenesulfonate. This application does not impose any particular limitation on the concentration of the sodium salt in the electrolyte, as long as the purpose of this application is achieved. For example, the concentration of the sodium salt is 1.0 mol / L to 2.0 mol / L.

[0080] The sodium-ion battery of this application also includes a casing. This application does not impose any particular limitations on the casing, and those skilled in the art can choose one according to actual needs, as long as it can achieve the purpose of this application. For example, the casing may include an aluminum-plastic film.

[0081] This application does not impose any particular limitation on the preparation method of sodium-ion batteries. Any preparation method known in the art can be used, as long as it can achieve the purpose of this application. For example, the preparation method of sodium-ion batteries includes, but is not limited to, the following steps: stacking the positive electrode, separator, and negative electrode in sequence, and winding and folding them as needed to obtain a bare cell with a wound structure; placing the bare cell in a packaging bag; injecting electrolyte into the packaging bag and sealing it to obtain a sodium-ion battery.

[0082] This application also provides a battery pack, including a housing and at least one sodium-ion battery according to any of the above embodiments, wherein the sodium-ion battery is housed within the housing. The battery pack with these two batteries exhibits excellent performance, which is beneficial for its use. Housed within the housing, the batteries are secured and protected, thus extending the battery pack's lifespan. It is understood that the battery pack may contain one or more sodium-ion batteries, and when the battery pack contains multiple sodium-ion batteries, these batteries can be connected in at least one manner, such as in parallel or in series.

[0083] This application also provides an electrical device including a sodium-ion battery or battery pack as described in any of the above embodiments, which is beneficial for improving the product competitiveness and performance of the electrical device. In an optional embodiment, the electrical device includes a device body, and the sodium-ion battery or battery pack is used to power the device body. In an optional embodiment, the device body includes a positive electrode and a negative electrode, the positive electrode of the sodium-ion battery or battery pack is used to electrically connect to the positive electrode of the device body, and the negative electrode of the sodium-ion battery or battery pack is used to electrically connect to the negative electrode of the device body, so as to power the electrical device.

[0084] The electrical equipment covered by this application may include, but is not limited to: containers, household energy storage systems, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools, etc. Among them, spacecraft include, for example, airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include, for example, stationary or mobile electric toys, specifically, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include, for example, metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, specifically, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0085] Please see Figure 1 , Figure 1This is a schematic diagram of the structure of a residential energy storage system according to one embodiment of this application, and this application... Figure 1 The implementation plan is illustrated using the residential energy storage scenario in user-side energy storage as an example. The energy storage device in this application is not limited to the residential energy storage scenario.

[0086] This application provides a residential energy storage system, which includes a power conversion device 2 (photovoltaic panel), a first user load 3 (streetlight), a second user load 4 (e.g., household appliances such as air conditioners), and an energy storage device 1. The energy storage device 1 is a small energy storage box that can be wall-mounted to an outdoor wall. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices, and the energy storage device 1 is used to store this electrical energy and supply it to streetlights and household appliances during periods of high electricity prices, or to provide power during power outages / power failures.

[0087] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy storage system 400 according to one embodiment of this application, and this application Figure 2 The implementation plan is illustrated using the shared energy storage scenario on the power generation / distribution side as an example. The energy storage device 1 in this application is not limited to the power generation / distribution side energy storage scenario.

[0088] This application provides an energy storage system 400, which includes a high-voltage cable 410, a first power conversion device 420, a second power conversion device 430, and the energy storage device 1 provided in this application. During power generation, the first power conversion device 420 and the second power conversion device 430 convert other forms of energy into electrical energy, which is then connected to the high-voltage cable 410 and supplied to the power consumption side of the distribution network. When the power load is low and the first power conversion device 420 and the second power conversion device 430 generate excess power, the excess power is stored in the energy storage device 1, reducing wind and solar curtailment rates and improving the absorption of new energy power generation. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 1, along with the high-voltage cable 410, in a grid-connected mode to supply power to the power consumption side. This provides various services such as peak shaving, frequency regulation, and backup for the power grid operation, fully leveraging the peak shaving function of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure on the power grid.

[0089] Optionally, the first power conversion device 420 and the second power conversion device 430 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electrical energy.

[0090] The number of energy storage devices 1 can be multiple, and these devices can be connected in series or in parallel. The multiple energy storage devices 1 are supported and electrically connected by an isolation plate (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box can also be provided outside the energy storage device 1 to house it.

[0091] Optionally, the energy storage device 1 may include, but is not limited to, a single battery cell, a battery module, a battery pack, or a battery system. The actual application form of the energy storage device 1 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 1. This application embodiment only uses a multi-cell battery as an example for illustration. When the energy storage device 1 is a single battery cell, the energy storage device 1 may be at least one of cylindrical batteries, prismatic batteries, etc.

[0092] Example

[0093] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0094] Example 1

[0095] <Preparation of Sodium Supplement Materials>

[0096] 30g of commercially available sodium supplement Na2C4O4 powder was added to a beaker containing 900mL of deionized water and stirred for 30min to completely dissolve the sodium supplement, thus obtaining a sodium supplement solution. 2500mL of anhydrous ethanol was added to the sodium supplement solution and stirred for 60min to generate Na2C4O4 precipitate. The precipitate was filtered with anhydrous ethanol and then washed to obtain the bottom precipitate. The bottom precipitate was then dried under vacuum at 110℃ for 24h to obtain recrystallized Na2C4O4, which is Na2C4O4 after particle size control treatment, with a D50 of 2.83μm.

[0097] 10g of the prepared recrystallized Na₂C₄O₄ was weighed and dissolved in 75mL of anhydrous ethanol. After ultrasonic dispersion for 30min, a dispersion was obtained. 1.6mL of tetrabutyl titanate was added to the dispersion, and after ultrasonic dispersion for 30min, the mixture was dried at 60℃ to remove ethanol, resulting in a mixture. The mixture was calcined at 360℃ for 4h under a nitrogen atmosphere, crushed, and sieved to obtain a sodium-supplementing material with a D50 of 1.12μm. The sodium-supplementing material contained 90% Na₂C₄O₄ by mass, with the remainder being titanium dioxide.

[0098] <Preparation of Sodium Supplement Tablets>

[0099] The prepared sodium supplement material, the conductive agent Ketjen Black, and the binder PVDF were mixed in a mass ratio of 60:30:10, and the solvent N-methylpyrrolidone (NMP) was added and stirred evenly to obtain a sodium supplement agent slurry with a solid content of 60%. Then, the sodium supplement agent slurry was evenly coated on an aluminum foil with a thickness of 10 μm, and the single-sided coating thickness was 20 μm. Then, it was vacuum dried at 110 °C for 12 h to obtain a sodium supplement agent electrode sheet. The obtained sodium supplement agent electrode sheet was cut into a circular sheet with a diameter of 14 μm for use.

[0100] <Preparation of NFPP Positive Electrode Sheet>

[0101] The positive active material Na4Fe3(PO4)2(P2O7) (i.e., NFPP), the prepared sodium supplement material, the conductive agent Ketjen Black, and the binder PVDF were mixed in a mass ratio of 70:10:10:10, and then NMP was added and stirred evenly to obtain a positive electrode slurry with a solid content of 60%. Then, the positive electrode slurry was evenly coated on an aluminum foil with a thickness of 10 μm, and the single-sided coating thickness was 20 μm. Then, it was vacuum dried at 110 °C for 12 h to obtain an NFPP positive electrode sheet. The obtained NFPP positive electrode sheet was cut into a circular sheet with a diameter of 14 μm for use.

[0102] <Preparation of Electrolyte>

[0103] In an argon atmosphere glove box with a moisture content ≤ 1 ppm, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1, and then sodium salt NaClO4 was added and dissolved in the above solvent. After mixing evenly, an electrolyte was obtained. Among them, the molar concentration of NaClO4 in the electrolyte was 1 mol / L.

[0104] <Preparation of Separator>

[0105] A glass fiber membrane with a thickness of 260 μm was selected as the separator.

[0106] <Assembly of Button Cell>

[0107] <Assembly of the First Button Cell>

[0108] A circular sodium sheet with a diameter of 14 μm was used as the counter electrode. The above-prepared circular sodium supplement agent electrode sheet, separator, and circular sodium sheet were stacked in sequence, and the separator was placed in the middle of the circular sodium supplement agent electrode sheet and the circular sodium sheet to play an isolating role. Then, the prepared electrolyte was injected to assemble the first button cell.

[0109] <Assembly of the Second Button Cell>

[0110] Using a circular sodium sheet with a diameter of 14 μm as the counter electrode, the NFPP positive electrode, the separator, and the circular sodium sheet prepared above are stacked in sequence, with the separator positioned between the NFPP positive electrode and the circular sodium sheet to act as a separator. Then, the prepared electrolyte is injected to assemble a second coin cell.

[0111] Examples 2 to 4

[0112] Except for adjusting the type of sodium supplement agent according to Table 1 in the section on <Preparation of Sodium Supplement Material>, the rest is the same as in Example 1.

[0113] Examples 5 to 7

[0114] Except for the section on "Preparation of Sodium Supplementation Material," where the type of catalyst precursor was adjusted to match the type of metal oxide catalyst as shown in Table 1, the rest of the steps were the same as in Example 1. Specifically, the catalyst precursor in Example 5 was cobalt 2-ethylhexanoate, the catalyst precursor in Example 6 was manganese diethylhexanoate, and the catalyst precursor in Example 7 was stannous diethylhexanoate.

[0115] Examples 8 to 10

[0116] Except for adjusting the content of sodium supplementing agent and metal oxide catalyst in sodium supplementing material according to Table 1 in the <Preparation of Sodium Supplementing Material> section, the rest is the same as in Example 1.

[0117] Example 11

[0118] Except for adjusting the calcination temperature to 400°C and the calcination time to 3h in the <Preparation of Sodium Supplement Material>, the rest is the same as in Example 1.

[0119] Example 12

[0120] Except for adjusting the calcination temperature to 500°C and the calcination time to 2h in the <Preparation of Sodium Supplement Material>, the rest is the same as in Example 1.

[0121] Comparative Example 1

[0122] Except for using the recrystallized Na2C4O4 obtained in Example 1 directly as a sodium supplement, everything else is the same as in Example 1.

[0123] Comparative Example 2

[0124] Except for using commercially available sodium supplement Na2C4O4 directly as a sodium supplement material, the rest is the same as in Example 1.

[0125] Comparative Example 3

[0126] The preparation of the sodium supplement material is not carried out. That is, the first coin cell is not prepared, and the NFPP positive electrode sheet does not contain the sodium supplement material, so that the obtained second coin cell also does not contain the sodium supplement material. Otherwise, it is the same as Example 1.

[0127] <Preparation of NFPP Positive Electrode Sheet>

[0128] Mix the positive active material NFPP, Ketjen black, and PVDF in a mass ratio of 80:10:10, then add NMP and stir evenly to obtain a positive electrode slurry with a solid content of 60%. Then, uniformly coat the positive electrode slurry on an aluminum foil with a thickness of 10 μm, with a single-sided coating thickness of 20 μm, and then vacuum dry at 110 °C for 12 h to obtain the NFPP positive electrode sheet. Cut the obtained NFPP positive electrode sheet into circular pieces with a diameter of 14 μm for use.

[0129] Comparative Example 4

[0130] Except that <the preparation of the sodium supplement material> is different from Example 1, the rest is the same as Example 1.

[0131] <Preparation of the sodium supplement material>

[0132] Weigh 10 g of commercially available sodium supplement agent Na2C4O4 powder, mix it with a commercially available TiO2 catalyst (Alfa-039953) in a mass ratio of 90:10, stir evenly to obtain a mixture, and use the obtained mixture as the sodium supplement material.

[0133] Testing methods and equipment:

[0134] Testing of metal element content:

[0135] Use the focused electron beam of an SEM instrument (model SU8010) to excite secondary electrons, backscattered electrons, characteristic X-rays and other secondary information in a selected area on the surface of the sodium supplement material, collect and detect this secondary information and perform quantitative analysis of the composition. Specifically, select an arbitrary 500 nm × 500 nm rectangular area on the surface of the sodium supplement material as the first area, conduct the first EDS test on the first area to obtain the content of the metal elements belonging to the metal oxide catalyst, denoted as C0; then heat-treat the first area through the SEM device at an acceleration voltage of 10 kV for 5 min to melt the sodium supplement material in the first area, and conduct the second EDS test on the melted first area to obtain the content of the metal elements belonging to the metal oxide catalyst, denoted as C_{1}.

[0136] Testing of oxidation decomposition potential:

[0137] The first charge-discharge test of the first coin cell was carried out using the LAND test system, and the dQ / dV curve was obtained. The oxidation peak of the dQ / dV curve corresponds to the oxidation decomposition reaction of the sodium supplement material, and the potential corresponding to the oxidation peak of the dQ / dV curve is the oxidation decomposition potential of the sodium supplement material.

[0138] Material particle size testing:

[0139] The average particle size D50 of the sodium-supplementing material was measured using a laser particle size analyzer.

[0140] First charge capacity and first discharge capacity test:

[0141] The test temperature was 25℃. The coin cell battery was charged to 4V at a constant current of 0.1C, which is the charging stage. After resting for 10 minutes, it was discharged to 2V at a constant current of 0.1C, and then rested for 10 minutes, which is the discharging stage. The charging capacity of the first charging stage was recorded as the first-cycle charging capacity, in mAh / g; the discharging capacity of the first discharging stage was also recorded as the first-cycle discharging capacity, in mAh / g.

[0142] Cyclic performance test:

[0143] The test temperature was 25℃. The coin cell battery was charged to 4V at a constant current of 0.1C, left to stand for 10 minutes, and then discharged to 2V at 0.1C. The capacity obtained in this step is the initial discharge capacity C. i Perform 20 cycles of 0.1C charge / 0.1C discharge, and record the discharge capacity on the 20th cycle. Cycle capacity retention = (Discharge capacity on the 20th cycle / Initial discharge capacity C) i )×100%.

[0144] Table 1. Data on sodium supplementation materials for each embodiment and comparative example.

[0145]

[0146] In Table 1, " / " indicates that no relevant preparation parameters exist.

[0147] Table 2 Performance data of the first button cell in each embodiment and comparative example

[0148]

[0149]

[0150] In Table 2, " / " indicates that no relevant test parameters exist.

[0151] Referring to Tables 1 and 2, it can be seen from Examples 1 and Comparative Examples 1 and 2 that when simply recrystallizing commercially available sodium supplements (e.g., Comparative Example 1) or directly using commercially available sodium supplements (e.g., Comparative Example 2) as sodium supplement materials, since the sodium supplement materials of Comparative Examples 1 and 2 do not contain metal oxide catalysts, they do not have the content of metal elements belonging to metal oxide catalysts after two EDS tests. This also indicates that the sodium supplement materials of Comparative Examples 1 and 2 do not have a composite structure of sodium supplement agent coating metal oxide catalyst. Furthermore, the sodium supplement materials of Comparative Examples 1 and 2 have high oxidation decomposition potentials and low first-cycle charging capacity of the first coin cell, making it difficult to improve the first-cycle sodium supplementation effect. From Examples 1 and 4, it can be seen that when simply physically mixing commercially available sodium supplements with commercially available TiO2 catalysts as sodium supplement materials, C1 < C0 after two EDS tests, indicating that the sodium supplement material of Comparative Example 4 also does not have a composite structure of sodium supplement agent coating metal oxide catalyst. Furthermore, the sodium-supplementing material in Comparative Example 4 has a high oxidation decomposition potential, resulting in a low first-cycle charging capacity of the first coin cell, making it difficult to improve the first-cycle sodium-supplementing effect. However, the sodium-supplementing material of this application, after two EDS tests, shows C1 > C0, indicating that it possesses a composite structure of a sodium-supplementing agent coated with a metal oxide catalyst. This results in a low oxidation decomposition potential, significantly improving the first-cycle charging capacity of the first coin cell and thus enhancing the first-cycle sodium-supplementing effect.

[0152] Figure 3 The image shows a SEM image of the sodium-supplementing material prepared in Example 1. Figure 3 As can be seen, there are no obvious TiO2 particles on the surface of the sodium supplement Na2C4O4, which confirms that the sodium supplement material of this application has a composite structure of sodium supplement agent coated with metal oxide catalyst.

[0153] Figure 4 The image shows a SEM image of the sodium-supplementing material prepared in Comparative Example 4. Figure 4 As can be seen, TiO2 particles are only dispersed on the surface of the sodium supplement Na2C4O4 and do not form a composite structure of sodium supplement coating metal oxide catalyst.

[0154] The type and content of sodium supplementer and metal oxide catalyst, as well as the particle size of sodium supplement material, also affect the performance of sodium-ion batteries. As can be seen from Examples 2 to 10, under the premise that C1 > C0, by controlling the type and content of sodium supplementer and metal oxide catalyst, as well as the particle size of sodium supplement material within the scope of this application, it is beneficial to obtain sodium-ion batteries with high first-cycle charging capacity.

[0155] Calcination time and temperature also affect the performance of sodium-ion batteries. As can be seen from Examples 11 and 12, under the premise that C1 > C0, by adjusting the calcination time and temperature within the range of this application, it is beneficial to obtain sodium-ion batteries with high first-cycle charging capacity.

[0156] Table 3 Performance data of the second button cell in each embodiment and comparative example

[0157]

[0158] Referring to Tables 1 and 3, it can be seen from Examples 1 and Comparative Examples 1 to 4 that when commercially available sodium supplements are simply recrystallized (e.g., Comparative Example 1), or commercially available sodium supplements are directly used (e.g., Comparative Example 2) as sodium supplement materials, or the positive electrode does not contain sodium supplement materials (e.g., Comparative Example 3), or commercially available sodium supplements are physically mixed with commercially available TiO2 catalysts and used as sodium supplement materials (e.g., Comparative Example 4), the sodium supplement materials in Comparative Examples 1, 2, and 4 do not have a composite structure of sodium supplements coated with metal oxide catalysts, and the positive electrode in Comparative Example 3 does not contain sodium supplement materials. Therefore, the first-cycle charging capacity and first-cycle discharging capacity of the second coin cell are both low, resulting in low first-cycle coulombic efficiency, which is detrimental to improving the energy density and cycle performance of sodium-ion batteries. However, the first-cycle charging capacity, first-cycle discharging capacity, and capacity retention rate after 20 cycles of the second coin cell of this application are significantly improved, thus contributing to the improvement of the energy density and cycle performance of sodium-ion batteries.

[0159] The type and content of sodium supplementer and metal oxide catalyst, as well as the particle size of sodium supplement material, also affect the performance of sodium-ion batteries. As can be seen from Examples 2 to 10, under the premise that C1 > C0, by controlling the type and content of sodium supplementer and metal oxide catalyst, as well as the particle size of sodium supplement material within the scope of this application, it is beneficial to obtain NFPP sodium-ion batteries with high first-cycle charging capacity, high first-cycle discharging capacity, and excellent cycle performance.

[0160] Calcination time and temperature also affect the performance of sodium-ion batteries. As can be seen from Examples 11 and 12, under the premise that C1 > C0, by adjusting the calcination time and temperature within the range of this application, it is beneficial to obtain an NFPP sodium-ion battery with high first-cycle charge capacity, high first-cycle discharge capacity, and excellent cycle performance.

[0161] Figure 5 The dQ / dV differential capacity curve is shown for the first charge cycle of the first coin cell in Example 1. Figure 6 This is a dQ / dV differential capacity curve for the first charging cycle of the first coin cell in Comparative Example 1. From... Figure 5It can be seen that the oxidation peak potential in Example 1 is 4.12V; from Figure 6 As can be seen, the oxidation peak potential of Comparative Example 1 is 4.25V, indicating that the sodium replenishment material of this application has a lower oxidation decomposition potential, which is beneficial to improving the sodium replenishment effect in the first cycle.

[0162] Figure 7 The first charge-discharge curve of the second coin cell in Example 1; Figure 8 The first charge-discharge curve of the second coin cell in Comparative Example 3 is shown. Figure 7 It can be seen that the first-cycle charging capacity of the second coin cell in Example 1 increased to 138.4 mAh / g, and an oxidation plateau was observed at around 4.12V. The capacity provided by this plateau corresponds to the oxidative decomposition process of the sodium-supplementing material. Figure 8 As can be seen, the first-cycle charging capacity of Comparative Example 3 is 115.7 mAh / g, and its first-cycle charging plateau shows oxidation plateaus at approximately 2.8V, 2.95V, and 3.28V, corresponding to the Na desorption processes at Na3, Na1, and Na4 sites, respectively. Furthermore, the first-cycle discharge specific capacity of Example 1 is 105.1 mAh / g, while that of Comparative Example 3 is 101.5 mAh / g. Moreover, the capacity retention rate of Example 1 after 20 cycles is also improved compared to Comparative Example 1. This indicates that the addition of the sodium-supplementing material in this application does not affect the structure of the NFPP cathode sheet during subsequent cycles, and may even have a positive effect. Therefore, the sodium-supplementing material in this application can effectively compensate for the sodium loss in the first cycle of the NFPP cathode sheet, showing good compatibility with the NFPP cathode sheet, which is beneficial to improving the energy density and cycle performance of sodium-ion batteries.

[0163] The above provides a detailed description of a sodium-supplementing material, its preparation method, the positive electrode sheet, and the sodium-ion battery disclosed in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A sodium supplement material, characterized in that, Including sodium supplements Na x C y O z H w And metal oxide catalysts, 1≤x≤3, 1≤y≤6, 1≤z≤7, 0≤w≤5; A first EDS test was performed on any first region on the surface of the sodium-supplementing material, and the content of the metal element belonging to the metal oxide catalyst was measured to be C0. A second EDS test was performed on the first region after melting, and the content of the metal element belonging to the metal oxide catalyst was measured to be C1, where C1 > C0.

2. The sodium supplement material according to claim 1, characterized in that, The sodium-supplementing material has a composite structure in which the sodium-supplementing agent coats the metal oxide catalyst.

3. The sodium supplement material according to claim 1, characterized in that, The oxidation decomposition potential of the sodium supplement material is E. pa 4.10V≤E pa ≤4.20V.

4. The sodium supplement material according to claim 1, characterized in that, The D50 of the sodium supplement material is 0.8μm~2μm.

5. The sodium supplement material according to claim 1, characterized in that, Based on the mass of the sodium-supplementing material, the sodium-supplementing agent has a mass percentage content of 70% to 95%, and the metal oxide catalyst has a mass percentage content of 5% to 30%.

6. The sodium supplement material according to any one of claims 1 to 5, characterized in that, The sodium supplement is selected from at least one of CH3COONa, C6H5Na3O7, Na2C4O4, Na2CO3, Na2C2O4, and Na2C6O6.

7. The sodium supplement material according to any one of claims 1 to 5, characterized in that, The metal oxide catalyst is selected from at least one of titanium dioxide, manganese dioxide, cobalt tetroxide, iron tetroxide, and tin dioxide.

8. A method for preparing a sodium-supplementing material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The sodium supplement agent after particle size control treatment was mixed with an alcohol-based solvent to obtain a dispersion, wherein the D50 of the sodium supplement agent after particle size control treatment was 1μm~3μm; The catalyst precursor was added to the dispersion and mixed, and then dried to obtain a mixture; The mixture is calcined in a gaseous atmosphere at a temperature of 300℃ to 500℃ for 1 h to 6 h to obtain the sodium supplement material.

9. The preparation method according to claim 8, characterized in that, The method further includes: The particle size distribution of the sodium supplement is controlled by recrystallization, ball milling, crushing, or spray drying to obtain the sodium supplement after particle size control treatment.

10. The preparation method according to claim 8, characterized in that, The catalyst precursor is selected from at least one of tetrabutyl titanate, manganese diethylhexanoate, iron diethylhexanoate, cobalt 2-ethylhexanoate, and stannous diethylhexanoate.

11. The preparation method according to claim 8, characterized in that, The alcohol-based solvent is at least one of methanol, ethanol, and ethylene glycol.

12. The preparation method according to claim 8, characterized in that, The gas atmosphere includes any one of argon, nitrogen, and air.

13. A positive electrode plate, characterized in that, The device includes a current collector and a positive electrode active material layer disposed on at least one surface of the current collector, wherein the positive electrode active material layer includes a sodium-supplementing material as described in any one of claims 1 to 7, or includes a sodium-supplementing material prepared by the preparation method as described in any one of claims 8 to 12.

14. A sodium-ion battery, characterized in that, Includes the positive electrode sheet as described in claim 13.

15. A battery pack, characterized in that, It includes a housing and at least one sodium-ion battery as described in claim 14, the sodium-ion battery being housed within the housing.

16. An electrical appliance, characterized in that, Includes the sodium-ion battery of claim 14, or includes the battery pack of claim 15.

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