Sodium supplementing material and preparation method therefor, positive electrode sheet, sodium ion battery, battery pack, and electrical device

Abstract

The present application relates to the technical field of electrochemistry, and specifically discloses a sodium supplementing material and a preparation method therefor, a positive electrode sheet, a sodium ion battery, a battery pack, and an electrical device. The sodium supplementing material comprises a sodium supplementing agent NaxcyOzHw and a metal oxide catalyst, where 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 supplementing material, and the content of a metal element contained in 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 contained in the metal oxide catalyst is measured to be C1, where C1>C0.

Description

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

[0001] Priority information

[0002] This application requests the priority and rights of the Chinese patent application filed with the State Intellectual Property Office of China on March 18, 2024, with patent application number 202410308708.7 and application name “Sodium-supplementing material and preparation method thereof, positive electrode sheet, sodium-ion battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of electrochemical technology, and in particular to a sodium supplement material and a preparation method thereof, a positive electrode sheet, a sodium ion battery, a battery pack and an electrical device. Background Art

[0004] Sodium-ion batteries are expected to replace traditional lithium-ion batteries in the energy storage field due to their advantages such as low cost, abundant sodium resources and relatively high energy density.

[0005] Using a positive electrode sodium supplement to replenish sodium in the positive electrode can reduce the adverse effects of sodium loss on the electrochemical performance of sodium-ion batteries. However, existing positive electrode sodium supplements still suffer from high oxidative decomposition potentials, which limits their actual sodium replenishment effect in sodium-ion batteries, and the performance of sodium-ion batteries needs to be improved. Summary of the Invention

[0006] In order to solve the above technical problems, the present application discloses a sodium supplement material and a preparation method thereof, a positive electrode sheet, a sodium ion battery, a battery pack and an electrical device to improve the performance of the sodium ion battery.

[0007] In the first aspect, the present application provides a sodium supplement material, including a sodium supplement agent Na x C y O z H w and a metal oxide catalyst, 1≤x≤3, 1≤y≤6, 1≤z≤7, 0≤w≤5; performing a first EDS test on any first area on the surface of the sodium-supplementing material, and measuring the content of the metal element belonging to the metal oxide catalyst to be C0; performing a second EDS test on the first area after melting, and measuring the content of the metal element belonging to the metal oxide catalyst to be C1, C1>C0.

[0008] In a second aspect, the present application provides a method for preparing the sodium supplement material as described in the first aspect, comprising the following steps:

[0009] The sodium supplement agent after the particle size control treatment is mixed with an alcohol-based solvent to obtain a dispersion, wherein the median particle size D50 of the sodium supplement agent after the particle size control treatment is 1 μm to 3 μm;

[0010] adding a catalyst precursor to the dispersion, mixing the mixture, and drying the mixture to obtain a mixture;

[0011] The mixture is calcined in a gas atmosphere at a calcination temperature of 300° C. to 500° C. and a calcination time of 1 hour to 6 hours to obtain the sodium supplement material.

[0012] In a third aspect, the present application provides a positive electrode plate comprising 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 comprises the sodium-supplementing material as described in the first aspect, or comprises the sodium-supplementing material prepared by the preparation method as described in the second aspect.

[0013] In a fourth aspect, the present application provides a sodium ion battery, comprising the positive electrode sheet described in the third aspect.

[0014] In a fifth aspect, the present application provides a battery pack comprising a housing and at least one sodium-ion battery as described in the fourth aspect, wherein the sodium-ion battery is housed in the housing.

[0015] In a sixth aspect, the present application provides an electrical device comprising the sodium ion battery described in the fourth aspect or the battery pack described in the fifth aspect.

[0016] Compared with the prior art, this application has at least the following beneficial effects:

[0017] The present application provides a sodium supplement material and a preparation method thereof, a positive electrode plate, and a sodium ion battery, wherein the sodium supplement material includes a sodium supplement agent Na x C y O z H w A first EDS (Energy Dispersive X-ray Spectroscopy) test is performed on any first region of 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. The sodium-supplementing material with the above characteristics is conducive to electron transfer, resulting in a low oxidative decomposition potential of the sodium-supplementing material, thereby improving the first-cycle sodium-supplementing effect of the sodium-supplementing material and improving the energy density and cycle performance of the sodium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the implementation scheme of the present application, the following is a brief introduction to the drawings required for use in the implementation scheme. Obviously, the drawings described below are only some implementation schemes of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] FIG1 is a schematic structural diagram of a household energy storage system according to an embodiment of the present application;

[0020] FIG2 is a schematic structural diagram of an energy storage system according to an embodiment of the present application;

[0021] FIG3 is a scanning electron microscope (SEM) image of the sodium supplement material prepared in Example 1;

[0022] FIG4 is a SEM image of the sodium supplement material prepared in Comparative Example 4;

[0023] FIG5 is a dQ / dV differential capacity curve diagram of the first button battery in the first cycle charging process of Example 1;

[0024] FIG6 is a dQ / dV differential capacity curve of the first button battery of Comparative Example 1 during the first cycle of charging;

[0025] FIG7 is a first cycle charge and discharge curve of the second button battery of Example 1;

[0026] FIG8 is a first cycle charge and discharge curve of the second button battery of Comparative Example 3.

[0027] Explanation of the accompanying drawings: 1-energy storage device, 2-electric energy conversion device, 3-first user load, 4-second user load, 400-energy storage system, 410-high voltage cable, 420-first electric energy conversion device, 430-second electric energy conversion device. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] In this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe this application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0030] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0031] Furthermore, the terms "installed," "disposed," "provided with," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections, indirect connections through an intermediary, or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0032] Furthermore, the terms "first," "second," etc., are primarily used to distinguish between different devices, elements, or components (which may or may not be of the same type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0033] The present application provides a sodium supplement material, which includes a sodium supplement agent Na x C y O z H wand a metal oxide catalyst, wherein 1≤x≤3, 1≤y≤6, 1≤z≤7, 0≤w≤5; a first EDS test is performed on any first area 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, and a second EDS test is performed on the first area after melting, and the content of the metal element belonging to the metal oxide catalyst is measured to be C1, C1>C0. The sodium-supplementing material of the present application has the above-mentioned characteristics, indicating that after the sodium-supplementing material of the present application is melted, the exposed metal oxide catalyst becomes more, which indicates that the metal oxide catalyst in the sodium-supplementing material of the present application is effectively coated by the sodium-supplementing agent, and this coating structure is conducive to electron transfer, so that the sodium-supplementing material has a low oxidative decomposition potential, thereby improving the first-cycle sodium-supplementing effect of the sodium-supplementing material. The sodium-supplementing material of the present application can release additional sodium ions during the first cycle charging process of the sodium-ion battery, thereby compensating for the sodium ion loss caused by the formation of the SEI film at the negative electrode and other side reactions, thereby improving the energy density and cycle performance of the sodium-ion battery.

[0034] In the present 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 500 nm × 500 nm, or a region of 0.25 μm 2 ~1μm 2 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 particularly limit the heat treatment method, as long as the sodium-supplementing material can be melted. For example, the first region can be heat treated using an SEM device at an accelerating voltage of 10 kV or 20 kV.

[0035] It is understood that the EDS test can be used to quantitatively analyze the content of various elements in the sodium supplement material, such as the metal element content of the metal oxide catalyst. In one example, the metal oxide catalyst is titanium dioxide (TiO2). The titanium content can be obtained after the first EDS test, recorded as C0, and the titanium content can be obtained after the second EDS test, recorded as C1.

[0036] In some embodiments of the present application, the sodium-supplementing material comprises a composite structure of a sodium-supplementing agent coated with a metal oxide catalyst. This composite structure facilitates electron transfer, resulting in a low oxidative decomposition potential for the sodium-supplementing material, thereby enhancing the sodium-supplementing effect of the sodium-supplementing material during the first cycle of charging. This allows for the release of additional sodium ions during the first cycle of charging a sodium-ion battery, thereby improving the energy density and cycle performance of the sodium-ion battery.

[0037] In some embodiments of the present application, the oxidative decomposition potential of the sodium supplement material is E pa, meeting 4.10V≤E pa ≤4.20 V, for example, the oxidative decomposition potential is 4.10 V, 4.12 V, 4.14 V, 4.15 V, 4.16 V or 4.20 V. The sodium-supplementing material of the present application has a lower oxidative decomposition potential than existing sodium-supplementing materials, can improve the first-cycle sodium-supplementing effect, improve the first-cycle irreversible capacity loss of the sodium-ion battery, and thus improve the first-cycle coulombic efficiency of the sodium-ion battery.

[0038] In this application, the oxidative decomposition potential refers to the potential corresponding to the oxidative decomposition reaction of the sodium supplement material during the charging process.

[0039] In some embodiments of the present application, the median particle size D50 of the sodium-supplementing material is between 0.8 μm and 2 μm, for example, D50 is 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, or 2 μm. By regulating the D50 of the sodium-supplementing material within the above range, the electron transmission distance between the sodium-supplementing material particles can be effectively shortened, thereby promoting the oxidative decomposition process of the sodium-supplementing agent and facilitating a reduction in the oxidative decomposition potential of the sodium-supplementing material.

[0040] In some embodiments of the present application, based on the total mass of the sodium-supplementing material being 100%, the mass percentage of the sodium-supplementing agent is 70% to 95%, and the mass percentage of the metal oxide catalyst is 5% to 30%. For example, the mass percentage of the sodium-supplementing agent is 70%, 75%, 80%, 85%, 90% or 95%; the mass percentage of the metal oxide catalyst is 5%, 10%, 15%, 20%, 25% or 30%. By regulating the mass ratio of the sodium-supplementing agent and the metal oxide catalyst in the sodium-supplementing material within the above range, 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 encapsulates the metal oxide catalyst.

[0041] In some embodiments of the present application, the sodium supplement is selected from at least one of CH3COONa, C6H5Na3O7, Na2C4O4, Na2CO3, Na2C2O4 and Na2C6O6. The above sodium supplement has the advantages of being environmentally friendly, widely available, safe and non-toxic.

[0042] In some embodiments of the present application, the metal oxide catalyst is selected from at least one of titanium dioxide, ruthenium dioxide, manganese dioxide, molybdenum dioxide, cobalt trioxide, ferrous oxide, and tin dioxide. These metal oxides can act as electron acceptors to accept electrons, thereby facilitating the formation of a composite structure in which the sodium supplementer encapsulates the metal oxide catalyst.

[0043] In a second aspect, the present application provides a method for preparing the sodium supplement material as described in the first aspect, comprising the following steps:

[0044] Preparation of a dispersion: mixing the sodium supplement agent after particle size control with an alcohol-based solvent to obtain a dispersion, wherein the median particle size D50 of the sodium supplement agent after particle size control is 1 μm to 3 μm;

[0045] Preparation of the mixture: adding the catalyst precursor to the dispersion, mixing, and drying to obtain a mixture;

[0046] Preparation of sodium-supplementing material: calcining the mixture in a gas atmosphere at a calcination temperature of 300° C. to 500° C. for a calcination time of 1 h to 6 h to obtain the sodium-supplementing material.

[0047] In the step of preparing the dispersion, the sodium supplement agent can be regulated by controlling the particle size of the sodium supplement agent to obtain a sodium supplement agent with the above-mentioned particle size range. The inventors have found that as the particle size of the sodium supplement agent decreases, its specific surface area increases accordingly. In the subsequent preparation process of the mixture, the dispersion formed after the catalyst precursor is dissolved in the alcohol-based solvent can be more evenly distributed on the surface of the sodium supplement agent; after further research, the inventors found that the uniformity of the mixing of the catalyst precursor and the sodium supplement agent will affect the uniformity of the coating structure of the sodium supplement material obtained after calcination. Based on this, the present application uses a sodium supplement agent after particle size regulation to prepare a 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.

[0048] In the step of preparing the mixture, using a catalyst precursor instead of directly using a metal oxide catalyst can make the sodium supplement agent and the catalyst precursor mixed evenly at the nanoscale, which is beneficial to making the coating structure of the sodium supplement material more uniform.

[0049] In the preparation step of the sodium-supplementing material, through the calcination process of the present application, that is, by regulating the calcination temperature and calcination time within the above range, the transition metal oxide produced by the thermal decomposition process of the metal alkoxide can be introduced into the sodium-supplementing agent, and the catalyst precursor undergoes a thermal decomposition reaction to form a transition metal oxide, and other components produced by the thermal decomposition (such as small organic molecules, carbon monoxide, carbon dioxide and water, etc.) are vaporized and discharged. In addition, 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, thereby forming a composite structure of the sodium-supplementing agent-coated metal oxide catalyst that is conducive to electron transfer.

[0050] In the step of preparing the sodium-supplementing material, the calcined product can be crushed by a crusher and sieved to obtain the sodium-supplementing material in the desired particle size range.

[0051] In some embodiments of the present application, the method for preparing the sodium supplement material further comprises:

[0052] The particle size distribution of the sodium supplement is regulated by recrystallization, ball milling, crushing or spray drying to obtain the sodium supplement after particle size regulation.

[0053] The present application can reduce the particle size of the sodium supplement agent by treatment methods such as recrystallization, ball milling, crushing or spray drying. The inventors have found that the commercially available sodium supplement agent has the disadvantage of large particle size, and recrystallization can effectively reduce the particle size of the sodium supplement agent. For example, when using recrystallization to control the particle size of the sodium supplement agent, the following steps can be followed:

[0054] Add commercially available sodium supplement powder to deionized water and stir until the sodium supplement is completely dissolved to obtain a nearly saturated sodium supplement solution;

[0055] Add anhydrous ethanol to the sodium supplement solution and stir to form a precipitate;

[0056] The precipitate is filtered and washed with anhydrous ethanol, and then vacuum dried at 110° C. to 130° C. for 24 h to 36 h to obtain a recrystallized sodium-supplementing material. After sieving, a sodium-supplementing material with a desired particle size is obtained.

[0057] In some embodiments of the present 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 catalyst precursor contains a transition metal element or a post-transition metal element, and in subsequent preparation steps, the transition metal oxide produced during the thermal decomposition of the organometallic salt can be introduced into the sodium supplement, forming a composite structure of the sodium supplement coated with the metal oxide catalyst, which is conducive to electron transfer.

[0058] In some embodiments of the present application, the alcohol-based solvent is selected from at least one of methanol, ethanol and ethylene glycol, which is conducive to the dissolution of the catalyst precursor.

[0059] The present application has no particular limitation on the gas atmosphere during calcination, as long as the purpose of the present application can be achieved. In some embodiments of the present application, the gas atmosphere includes any one of argon, nitrogen and air.

[0060] The preparation method of the sodium-supplementing material provided in the present application is based on calcining a sodium-supplementing agent after particle size control treatment and a catalyst precursor, which can make the coating structure of the sodium-supplementing material more uniform, which is conducive to obtaining a sodium-supplementing material with better sodium-supplementing performance. In addition, the preparation method of the present application is simple, and the prepared sodium-supplementing material has 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.

[0061] The present application also provides a positive electrode plate, comprising a current collector and a positive electrode active material layer arranged on at least one surface of the current collector, the positive electrode active material layer comprising the sodium-supplementing material described in any of the above embodiments, or comprising the sodium-supplementing material prepared by the preparation method described in any of the above embodiments.

[0062] The positive electrode active material layer of the present application can be arranged on one surface or both surfaces in the thickness direction of the positive electrode current collector. In the present application, the positive electrode active material layer is arranged on the surface of the positive electrode current collector, that is, the positive electrode active material layer can be arranged in a partial area of ​​one surface of the positive electrode current collector, or it can be arranged in the entire area of ​​one surface of the positive electrode current collector. The present application has no special restrictions on the positive electrode current collector, as long as the purpose of the present application can be achieved, for example, it can include but is not limited to aluminum foil, aluminum alloy foil or composite current collector, etc. In the present application, there is no special restriction on the thickness of the positive electrode current collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8μm to 13μm. The thickness of the positive electrode active material layer of the present application can be 150μm to 400μm.

[0063] In the present application, the positive electrode active material layer also includes a positive electrode active material. The present application has no special restrictions on the positive electrode active material, as long as the purpose of the present application can be achieved. For example, it may include at least one of sodium nickel manganate, sodium nickel iron manganate, sodium ferric sulfate, sodium vanadium phosphate, sodium copper iron manganate, sodium ferric pyrophosphate and sodium ferric pyrophosphate.

[0064] In the present application, the positive electrode active material layer may further include a positive electrode conductive agent. There is no particular limitation on the positive electrode conductive agent in the present application, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), 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 the present application, the positive electrode active material layer may further include a positive electrode binder. There is no particular limitation on the positive electrode binder in the present application, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of fluorine-containing resin, polypropylene resin, fiber-type binder, rubber-type binder, polyimide-type binder, and polyvinylidene fluoride (PVDF).

[0065] The present application also provides a sodium ion battery, comprising the positive electrode sheet described in any of the above embodiments.

[0066] The sodium ion battery of the present application also includes a negative electrode plate, a separator and an electrolyte, wherein the separator is located between the positive electrode plate and the negative electrode plate to play an isolation role.

[0067] The present application has no special restrictions on the negative electrode plate, as long as the purpose of the present application can be achieved. For example, the negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer can be arranged on the surface of the negative electrode current collector, that is, the negative electrode active material layer can be arranged in a partial area of ​​one surface of the negative electrode current collector, or it can be arranged in the entire area of ​​one surface of the negative electrode current collector. The present application has no special restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved. For example, it can include but is not limited to copper foil, copper alloy foil, nickel foil or composite current collector, etc. In the present application, there is no special restriction on the thickness of the negative electrode current collector, as long as the purpose of the present application can be achieved, for example, the thickness is 4μm to 12μm. The thickness of the negative electrode material layer of the present application can be 70μm to 200μm.

[0068] In the present application, the negative electrode active material layer may further include a negative electrode binder. The present application does not particularly limit the negative electrode binder, as long as it can achieve the purpose of the present application. For example, the negative electrode binder may include at least one of acrylate, polyamide, polyimide, polyamideimide, polyvinylidene fluoride, styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

[0069] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0070] The sodium ion battery of the present application also includes an electrolyte. The present application does not particularly limit the electrolyte, and those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be 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) is mixed in a certain mass ratio or volume ratio to obtain a non-aqueous organic solvent, and then sodium salt is added to dissolve and mix evenly. The present application does not limit the type of sodium salt, as long as the purpose of the present application can be achieved. For example, the sodium salt can include at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate and sodium p-toluenesulfonate. The present application does not particularly limit the concentration of the sodium salt in the electrolyte, as long as the purpose of the present application can be achieved. For example, the concentration of the sodium salt is 1.0 mol / L to 2.0 mol / L.

[0071] The sodium ion battery of the present application also includes a housing. The present application does not particularly limit the housing, and those skilled in the art can select it according to actual needs, as long as it can achieve the purpose of the present application. For example, the housing may include an aluminum-plastic film.

[0072] The present application does not particularly limit the preparation method of the sodium ion battery, and any preparation method known in the art may be selected as long as the purpose of the present application can be achieved. For example, the preparation method of the sodium ion battery includes but is not limited to the following steps: stacking the positive electrode sheet, the separator, and the negative electrode sheet in order, and performing operations such as winding and folding as needed to obtain a bare cell with a wound structure, placing the bare cell in a packaging bag, injecting an electrolyte into the packaging bag, and sealing the packaging bag to obtain a sodium ion battery.

[0073] The present application also provides a battery pack comprising a housing and at least one sodium-ion battery according to any of the above embodiments, wherein the sodium-ion battery is housed in the housing. The battery pack having these two batteries has excellent performance, which is beneficial for the use of the battery pack. By housing the battery in the housing, the fixation and protection of the battery can be increased, thereby improving the service life of the battery pack. It is understood that the battery pack may contain one or more sodium-ion batteries. When the battery pack contains multiple sodium-ion batteries, the multiple sodium-ion batteries may be connected in at least one of parallel and series connection.

[0074] The present application also provides an electrical device, including a sodium ion battery or battery pack in any of the above embodiments, which is conducive to improving the product competitiveness and performance of the electrical device. In an optional embodiment, the electrical device includes an electrical device body, and the sodium ion battery or battery pack is used to power the electrical device body. In an optional embodiment, the electrical device body includes a positive electrode and a negative electrode, the positive electrode plate of the sodium ion battery or battery pack is used to electrically connect to the positive electrode of the electrical device body, and the negative electrode plate of the sodium ion battery or battery pack is used to electrically connect to the negative electrode of the electrical device body to power the electrical device.

[0075] The electrical equipment of the present application may include but is not limited to: containers, household energy storage systems, battery vehicles, electric vehicles, ships, spacecraft, electric toys and electric tools, etc., among which spacecraft include airplanes, rockets, space shuttles and spacecraft, etc., electric toys include fixed or mobile electric toys, specifically electric car toys, electric ship toys and electric airplane toys, etc., and electric tools include 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.

[0076] Please refer to Figure 1, which is a structural diagram of a household energy storage system of an implementation scheme of the present application. The implementation scheme of Figure 1 of the present application is illustrated by taking the household energy storage scenario in user-side energy storage as an example. The energy storage device of the present application is not limited to the household energy storage scenario.

[0077] The present application provides a household energy storage system, which includes an energy conversion device 2 (photovoltaic panels), a first user load 3 (street lights), a second user load 4 (such as 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 mounted on an outdoor wall. Specifically, the photovoltaic panels can convert solar energy into electrical energy during periods of low electricity prices. The energy storage device 1 is used to store this electrical energy and supply it to street lights and household appliances for use during peak electricity prices, or to provide power during power outages / blackouts.

[0078] Please refer to Figure 2, which is a structural diagram of an energy storage system 400 of an implementation scheme of the present application. The implementation scheme of Figure 2 of the present application is illustrated by taking the shared energy storage scenario on the generation / distribution side as an example. The energy storage device 1 of the present application is not limited to its generation / distribution side energy storage scenario.

[0079] The present application provides an energy storage system 400, which includes: a high-voltage cable 410, a first electric energy conversion device 420, a second electric energy conversion device 430 and the energy storage device 1 provided in the present application. In the power generation state, the first electric energy conversion device 420 and the second electric energy conversion device 430 are used to convert other forms of energy into electric energy, which is connected to the high-voltage cable 410 and supplied to the power distribution network for use. When the power load is low and the first electric energy conversion device 420 and the second electric energy conversion device 430 generate excess power, the excess power is stored in the energy storage device 1, reducing the wind and solar power abandonment rates and improving the problem of new energy power generation and consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 1 in conjunction with the high-voltage cable 410 in a grid-connected mode to the power consumption side, providing peak shaving, frequency regulation, standby and other services for the power grid operation, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling of the power grid, and alleviating the power supply pressure of the power grid.

[0080] Optionally, the first electric energy conversion device 420 and the second electric energy 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 electric energy.

[0081] There can be multiple energy storage devices 1, connected in series or in parallel, and supported and electrically connected using isolation plates (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box may also be provided outside the energy storage device 1 to accommodate the energy storage device 1.

[0082] Optionally, the energy storage device 1 may include, but is not limited to, a single cell, a battery module, a battery pack, a battery system, and the like. The actual application form of the energy storage device 1 provided in the embodiments of this application may be, but is not limited to, the products listed, and may also be other application forms. The embodiments of this application do not impose strict restrictions on the application form of the energy storage device 1. The embodiments of this application only illustrate the energy storage device 1 as a multi-core battery. When the energy storage device 1 is a single cell, the energy storage device 1 may be at least one of a cylindrical battery, a prismatic battery, and the like.

[0083] Example

[0084] Hereinafter, the embodiments of the present application will be described in more detail with reference to Examples and Comparative Examples. Various tests and evaluations were performed according to the following methods.

[0085] Example 1

[0086] This embodiment includes the following steps:

[0087] Preparation of sodium supplementation materials:

[0088] 30 g of commercially available sodium supplement Na2C4O4 powder was added to a beaker containing 900 mL of deionized water and stirred for 30 minutes to completely dissolve the sodium supplement to obtain a sodium supplement solution. 2500 mL of anhydrous ethanol was added to the sodium supplement solution and stirred for 60 minutes to generate a Na2C4O4 precipitate. The precipitate was filtered with anhydrous ethanol and then washed to obtain a bottom precipitate, which was vacuum dried at 110°C for 24 hours to obtain recrystallized Na2C4O4, i.e., Na2C4O4 after particle size control treatment, with a D50 of 2.83 μm.

[0089] 10g of the prepared recrystallized Na2C4O4 was weighed and dissolved in 75mL of anhydrous ethanol. Ultrasonic dispersion was performed for 30 minutes to obtain a dispersion. 1.6mL of tetrabutyl titanate was added to the dispersion and ultrasonically dispersed for 30 minutes. The dispersion was then dried at 60°C to remove the ethanol, resulting in a mixture. The mixture was calcined at 360°C under a nitrogen atmosphere for 4 hours, crushed in a crusher, and sieved to obtain a sodium-supplementing material with a D50 of 1.12μm. The mass percentage of Na2C4O4 in the sodium-supplementing material was 90%, with the remainder being titanium dioxide.

[0090] Preparation of sodium supplement electrode:

[0091] 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 N-methylpyrrolidone (NMP) was added as a solvent and stirred evenly to obtain a sodium supplement slurry with a solid content of 60%. The sodium supplement slurry was then evenly coated onto a 10 μm thick aluminum foil to a thickness of 20 μm on one side. The foil was then vacuum-dried at 110°C for 12 hours to obtain a sodium supplement electrode. The obtained sodium supplement electrode was cut into 14 μm diameter discs for later use.

[0092] Preparation of NFPP positive electrode sheet:

[0093] The positive electrode active material Na4Fe3(PO4)2(P2O7) (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. NMP was then added and stirred evenly to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then evenly coated on a 10μm thick aluminum foil to a thickness of 20μm on one side. The NFPP positive electrode sheet was then vacuum dried at 110°C for 12 hours. The resulting NFPP positive electrode sheet was cut into 14μm diameter discs for later use.

[0094] Preparation of electrolyte:

[0095] In an argon atmosphere glove box with a moisture content of ≤1 ppm, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1. Sodium salt NaClO₄ was then added and dissolved in the solvent. After mixing thoroughly, an electrolyte solution was obtained. The molar concentration of NaClO₄ in the electrolyte solution was 1 mol / L.

[0096] Preparation of diaphragm:

[0097] A glass fiber membrane with a thickness of 260 μm was selected as the diaphragm.

[0098] Assembly of button battery:

[0099] Assembly of the first button battery:

[0100] A circular sodium sheet with a diameter of 14 μm was used as the counter electrode. The circular sodium supplement electrode, diaphragm and circular sodium sheet prepared above were stacked in order, so that the diaphragm was placed between the circular sodium supplement electrode and the circular sodium sheet to act as an isolate. Then the prepared electrolyte was injected to assemble the first button battery.

[0101] Assembly of the second button battery:

[0102] A circular sodium sheet with a diameter of 14 μm was used as the counter electrode. The NFPP positive electrode sheet, diaphragm and circular sodium sheet prepared above were stacked in order, with the diaphragm placed between the NFPP positive electrode sheet and the circular sodium sheet to act as an isolate. The prepared electrolyte was then injected to assemble the second button battery.

[0103] Example 2 to Example 4

[0104] Except that the type of sodium supplement agent was adjusted according to Table 1 in the preparation of the sodium supplement material, the rest was the same as Example 1.

[0105] Example 5 to Example 7

[0106] The preparation of the sodium supplement material was the same as in Example 1, except that the type of catalyst precursor was adjusted to adjust the type of metal oxide catalyst according to Table 1. The catalyst precursor of Example 5 was cobalt 2-ethylhexanoate, the catalyst precursor of Example 6 was manganese diethylhexanoate, and the catalyst precursor of Example 7 was stannous diethylhexanoate.

[0107] Example 8 to Example 10

[0108] Except that the contents of the sodium supplement agent and the metal oxide catalyst in the sodium supplement material were adjusted according to Table 1 during the preparation of the sodium supplement material, the rest was the same as in Example 1.

[0109] Example 11

[0110] Except that the calcination temperature was adjusted to 400° C. and the calcination time was adjusted to 3 h in the preparation of the sodium-supplementing material, the rest was the same as in Example 1.

[0111] Example 12

[0112] Except that the calcination temperature was adjusted to 500° C. and the calcination time was adjusted to 2 h in the preparation of the sodium-supplementing material, the rest was the same as in Example 1.

[0113] Comparative Example 1

[0114] Except that the recrystallized Na2C4O4 obtained in Example 1 is directly used as the sodium supplement material, the rest is the same as Example 1.

[0115] Comparative Example 2

[0116] Except that the commercially available sodium supplement agent Na2C4O4 is directly used as the sodium supplement material, the rest is the same as Example 1.

[0117] Comparative Example 3

[0118] No sodium-supplementing material was prepared, that is, no first button cell was prepared, and the NFPP positive electrode sheet did not contain sodium-supplementing material, so that the prepared second button cell also did not contain sodium-supplementing material. Other aspects were the same as in Example 1.

[0119] Preparation of NFPP positive electrode sheet:

[0120] The positive electrode active materials NFPP, Ketjen Black, and PVDF were mixed in a mass ratio of 80:10:10, and then NMP was added and stirred evenly to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry was then evenly coated on a 10μm thick aluminum foil to a thickness of 20μm on one side. The NFPP positive electrode sheet was then vacuum dried at 110°C for 12 hours to obtain the NFPP positive electrode sheet. The resulting NFPP positive electrode sheet was cut into 14μm diameter discs for later use.

[0121] Comparative Example 4

[0122] Except that the preparation of the sodium supplement material is different from that in Example 1, the rest is the same as that in Example 1.

[0123] Preparation of sodium supplementation materials:

[0124] Weigh 10 g of commercially available sodium supplement agent Na2C4O4 powder, mix it with 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 a sodium supplement material.

[0125] Test methods and equipment:

[0126] Metal element content test:

[0127] A focused electron beam from a SEM (model SU8010) was used to excite a selected area on the surface of the sodium-supplementing material, generating secondary electrons, backscattered electrons, and characteristic X-rays. This secondary information was then collected and detected for quantitative composition analysis. Specifically, a random 500nm x 500nm rectangular area on the surface of the sodium-supplementing material was selected as the first area. An EDS analysis was performed on this area to determine the content of metal elements associated with the metal oxide catalyst, denoted as C0. This area was then heat-treated at an accelerating voltage of 10kV for 5 minutes using the SEM to melt the sodium-supplementing material. A second EDS analysis was performed on this melted area to determine the content of metal elements associated with the metal oxide catalyst, denoted as C1.

[0128] Oxidative decomposition potential test:

[0129] The first button cell was subjected to the first cycle charge and discharge test using the LAND test system to obtain a dQ / dV curve. The oxidation peak of the dQ / dV curve corresponds to the oxidative decomposition reaction of the sodium-supplementing material, and the potential corresponding to the oxidation peak of the dQ / dV curve is the oxidative decomposition potential of the sodium-supplementing material.

[0130] Material particle size test:

[0131] The average particle size D50 of the sodium supplement material was tested using a laser particle size analyzer.

[0132] First cycle charging capacity and first cycle discharging capacity test:

[0133] The test temperature is 25°C. Charge the button cell at a constant current of 0.1C to 4V (the charging phase). Allow the cell to rest for 10 minutes, then discharge it at a constant current of 0.1C to 2V. Allow the cell to rest for 10 minutes (the discharging phase). Record the charge capacity during the first charge phase as the first cycle charge capacity (in mAh / g). Record the discharge capacity during the first discharge phase as the first cycle discharge capacity (in mAh / g).

[0134] Cyclic performance test:

[0135] The test temperature is 25℃. Charge the button battery to 4V at 0.1C constant current, let it stand for 10 minutes, and then discharge it 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 at the 20th cycle. Cycle capacity retention rate = (discharge capacity at the 20th cycle / initial discharge capacity C i )×100%.

[0136] Table 1 Data of sodium supplement materials in various embodiments and comparative examples In Table 1, “ / ” indicates that there are no relevant preparation parameters.

[0137] Table 2 Performance data of the first button battery of each embodiment and comparative example In Table 2, “ / ” indicates that there is no relevant test parameter.

[0138] Combining Tables 1 and 2, it can be seen from Example 1 and Comparative Examples 1 and 2 that when a commercially available sodium supplement is simply recrystallized (e.g., Comparative Example 1) or directly used as a sodium supplement material (e.g., Comparative Example 2), since the sodium supplement materials of Comparative Examples 1 and 2 do not contain a metal oxide catalyst, after two EDS tests, they do not contain the metal element content of the metal oxide catalyst. This also indicates that the sodium supplement materials of Comparative Examples 1 and 2 do not have a composite structure of a sodium supplement coated with a metal oxide catalyst. Furthermore, the sodium supplement materials of Comparative Examples 1 and 2 have high oxidative decomposition potentials, resulting in low first-cycle charge capacities of the first button cell, making it difficult to improve the sodium supplement material's first-cycle sodium supplement effect. It can be seen from Example 1 and Comparative Example 4 that when a commercially available sodium supplement is simply physically mixed with a commercially available TiO2 catalyst and used as a sodium supplement material, after two EDS tests, C1 < C0, indicating that the sodium supplement material of Comparative Example 4 also does not have a composite structure of a sodium supplement coated with a metal oxide catalyst. Furthermore, the sodium-supplementing material in Comparative Example 4 had a high oxidative decomposition potential, resulting in a low first-cycle charge capacity in the first button cell. Therefore, it was difficult to improve the sodium-supplementing effect of the sodium-supplementing material in the first cycle. However, after two EDS tests, the sodium-supplementing material in the present application showed C1>C0, indicating that the sodium-supplementing material has a composite structure of a sodium-supplementing agent coated with a metal oxide catalyst, resulting in a low oxidative decomposition potential. This significantly improved the first-cycle charge capacity of the first button cell, thereby enhancing the sodium-supplementing effect of the sodium-supplementing material in the first cycle.

[0139] FIG3 is an SEM image of the sodium-supplementing material prepared in Example 1. As can be seen from FIG3 , there are no obvious TiO2 particles on the surface of the sodium-supplementing agent Na2C4O4, which also confirms that the sodium-supplementing material of the present application has a composite structure of a sodium-supplementing agent-coated metal oxide catalyst.

[0140] FIG4 is an SEM image of the sodium supplement material prepared in Comparative Example 4. It can be seen from FIG4 that the TiO2 particles are only dispersed on the surface of the sodium supplement agent Na2C4O4, and no composite structure of the sodium supplement agent-coated metal oxide catalyst is formed.

[0141] The type and content of the sodium supplement agent and metal oxide catalyst, as well as the particle size of the sodium supplement material, also affect the performance of the sodium ion battery. As can be seen from Examples 2 to 10, under the premise of C1>C0, by regulating the type and content of the sodium supplement agent and metal oxide catalyst, as well as the particle size of the sodium supplement material within the range of this application, a sodium ion battery with a high first-cycle charge capacity can be obtained.

[0142] Calcination time and temperature also affect the performance of sodium-ion batteries. From Examples 11 and 12, it can be seen that, under the premise of C1>C0, by regulating the calcination time and temperature within the scope of this application, it is beneficial to obtain a sodium-ion battery with a high first-cycle charge capacity.

[0143] Table 3 Performance data of the second button battery of each embodiment and comparative example

[0144] In combination with Table 1 and Table 3, it can be seen from Example 1 and Comparative Examples 1 to Comparative Examples 4 that when the commercially available sodium supplement is simply recrystallized (for example, Comparative Example 1), or the commercially available sodium supplement is directly used as the sodium supplement material (for example, Comparative Example 2), or the positive electrode sheet does not contain the sodium supplement material (for example, Comparative Example 3), or the commercially available sodium supplement is physically mixed with the commercially available TiO2 catalyst as the sodium supplement material (for example, Comparative Example 4), since the sodium supplement materials of Comparative Examples 1, 2, and 4 do not have a composite structure of a sodium supplement coated with a metal oxide catalyst, the positive electrode sheet of Comparative Example 3 does not contain a sodium supplement material, the first-cycle charge capacity and the first-cycle discharge capacity of the second button battery are both low, resulting in a low first-cycle coulomb efficiency, which is not conducive to the improvement of the energy density and cycle performance of the sodium ion battery; while the first-cycle charge capacity, the first-cycle discharge capacity, and the capacity retention rate after 20 cycles of the second button battery of the present application are significantly improved, which is beneficial to the improvement of the energy density and cycle performance of the sodium ion battery.

[0145] The type and content of the sodium supplement agent and metal oxide catalyst, as well as the particle size of the sodium supplement material, also affect the performance of the sodium ion battery. From Examples 2 to 10, it can be seen that, under the premise of C1>C0, by regulating the type and content of the sodium supplement agent and metal oxide catalyst, as well as the particle size of the sodium supplement material within the scope of this application, it is beneficial to obtain a NFPP sodium ion battery with high first-cycle charge capacity, high first-cycle discharge capacity, and excellent cycle performance.

[0146] Calcination time and temperature also affect the performance of sodium-ion batteries. As can be seen from Examples 11 and 12, under the premise of C1>C0, by regulating the calcination time and temperature within the scope of this application, it is beneficial to obtain NFPP sodium-ion batteries with high first-cycle charge capacity, high first-cycle discharge capacity, and excellent cycle performance.

[0147] Figure 5 is a graph showing the dQ / dV differential capacity curve during the first charge cycle of the first button-type battery of Example 1; Figure 6 is a graph showing the dQ / dV differential capacity curve during the first charge cycle of the first button-type battery of Comparative Example 1. As shown in Figure 5 , the oxidation peak potential of Example 1 is 4.12V; as shown in Figure 6 , the oxidation peak potential of Comparative Example 1 is 4.25V, indicating that the sodium-supplementing material of the present application has a lower oxidative decomposition potential, which is beneficial for improving the sodium-supplementing effect during the first charge cycle.

[0148] Figure 7 is the first cycle charge and discharge curve of the second button battery of Example 1; Figure 8 is the first cycle charge and discharge curve of the second button battery of Comparative Example 3. As can be seen from Figure 7, the first cycle charge capacity of the second button battery of Example 1 is increased to 138.4 mAh / g, and an oxidation platform is shown at about 4.12V. The capacity provided by this part of the platform corresponds to the oxidative decomposition process of the sodium supplement material; as can be seen from Figure 8, the first cycle charge capacity of Comparative Example 3 is 115.7 mAh / g, and its first cycle charge platform shows oxidation platforms at about 2.8V, 2.95V and 3.28V, corresponding to the Na3 site, Na1 site and Na4 site Na release process. Furthermore, the first cycle discharge specific capacity of Example 1 is 105.1 mAh / g, and the first cycle discharge specific capacity of Comparative Example 3 is 101.5 mAh / g, and the capacity retention rate after 20 cycles of Example 1 is also improved compared with Comparative Example 1, which shows that the addition of the sodium supplement material of the present application will not affect the structure of the NFPP positive electrode sheet in the subsequent cycle process, and even plays a positive role. From the above, it can be seen that the sodium-supplementing material of the present application can effectively compensate for the first-cycle sodium loss of the NFPP positive electrode sheet, showing good compatibility with the NFPP positive electrode sheet, which is beneficial to the improvement of the energy density and cycle performance of sodium-ion batteries.

[0149] The above is a detailed introduction to a sodium-supplementing material and its preparation method, a positive electrode sheet, and a sodium-ion battery disclosed in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core inventions of the embodiments of the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A sodium supplement material, wherein: 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 is performed on any first area 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 area after melting, and the content of the metal element belonging to the metal oxide catalyst is measured to be C1, and C1>C0.

2. The sodium supplement material according to claim 1, wherein The sodium supplement material has a composite structure in which the sodium supplement covers the metal oxide catalyst.

3. The sodium supplement material according to claim 1 or 2, wherein The oxidation decomposition potential of the sodium supplement material is E pa , meeting 4.10V≤E pa ≤4.20V.

4. The sodium supplement material according to any one of claims 1 to 3, wherein The median particle size D50 of the sodium supplementing material is 0.8 μm to 2 μm.

5. The sodium supplement material according to any one of claims 1 to 4, wherein Based on the total mass of the sodium-supplementing material being 100%, the mass percentage of the sodium-supplementing agent is 70% to 95%, and the mass percentage of the metal oxide catalyst is 5% to 30%.

6. The sodium supplement material according to any one of claims 1 to 5, wherein 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 6, wherein The metal oxide catalyst is selected from at least one of titanium dioxide, ruthenium dioxide, manganese dioxide, molybdenum dioxide, cobalt trioxide, ferrosoferric oxide and tin dioxide.

8. A method for preparing the sodium supplement material according to any one of claims 1 to 7, wherein: The following steps are involved: The sodium supplement agent after the particle size control treatment is mixed with an alcohol-based solvent to obtain a dispersion, wherein the median particle size D50 of the sodium supplement agent after the particle size control treatment is 1 μm to 3 μm; adding a catalyst precursor to the dispersion, mixing the mixture, and drying the mixture; The mixture is calcined in a gas atmosphere at a calcination temperature of 300° C. to 500° C. and a calcination time of 1 hour to 6 hours to obtain the sodium supplement material.

9. The preparation method according to claim 8, wherein The method further comprises: The particle size distribution of the sodium supplement is regulated by recrystallization, ball milling, crushing or spray drying to obtain the sodium supplement after the particle size regulation treatment.

10. The preparation method according to claim 8 or 9, wherein 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.

11. The preparation method according to any one of claims 8 to 10, wherein The alcohol-based solvent is at least one selected from methanol, ethanol and ethylene glycol.

12. The preparation method according to any one of claims 8 to 11, wherein The gas atmosphere includes any one of argon, nitrogen and air.

13. A positive electrode sheet, wherein: The invention comprises a current collector and a positive electrode active material layer provided on at least one surface of the current collector, wherein the positive electrode active material layer comprises the sodium-supplementing material according to any one of claims 1 to 7, or comprises the sodium-supplementing material prepared by the preparation method according to any one of claims 8 to 12.

14. A sodium ion battery, wherein: Including the positive electrode sheet according to claim 13.

15. A battery pack, wherein: The invention comprises a housing and at least one sodium ion battery according to claim 14, wherein the sodium ion battery is accommodated in the housing.

16. An electrical device, wherein: Includes the sodium ion battery according to claim 14, or includes the battery pack according to claim 15.

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