Lithium-supplementing agent and preparation method therefor, positive electrode sheet, separator, battery and electric device

Abstract

Provided in the present application are a lithium-supplementing agent and a preparation method therefor, a positive electrode sheet, a separator, a battery and an electric device. The lithium-supplementing agent of the present application comprises Li(5-x)MxFe(1-y)NyO4, wherein M comprises at least one metal element of Al, Mg, Ti, V, Ge, Ga, Rb and Cs, and N comprises at least one metal element of Al, Ti, V, Ge, Cr, Co, Mn, Ni, Cu, Zn, Y, Pd, Ag, Cd, Pt and Au, where 0.01≤x≤1, and 0≤y≤0.5. In the present application, by doping lithium-rich lithium ferrite with a specific element, the phase structure change of the lithium-rich lithium ferrite can be inhibited, and the structural stability of the lithium-rich lithium ferrite positive electrode material is improved, such that the lattice is not prone to deformation, which is beneficial for reducing the generation of residual alkali on the surface of the material, thereby reducing the influence of the residual alkali on the comprehensive performance of a lithium-supplementing battery, and meeting the requirements for a power battery.

Description

Lithium supplements and their preparation methods, positive electrode sheets, separators, batteries and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202411759820.9, filed on November 30, 2024, entitled "Lithium Supplement Agent and Preparation Method Thereof, Positive Electrode Sheet, Separator, Battery and Electrical Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of battery technology and relates to a lithium replenishing agent and its preparation method, a positive electrode, a separator, a battery, and an electrical device. Background Technology

[0003] Lithium replenishment agents can be used to replenish lithium in batteries, which can offset the capacity decay caused by the consumption of active lithium to a certain extent. For example, positive electrode lithium replenishment involves adding a compound that is easy to delithiate under high voltage to the positive electrode to replenish the lithium-ion battery with extra active lithium to offset the energy density decay caused by the consumption of active lithium. The use of lithium replenishment agents is relatively safe and convenient for industrial application.

[0004] Lithium-rich lithium iron ferrite (Li5FeO4) is a commonly used lithium supplement, but residual alkaline lithium compounds often form on its surface during the preparation process. Excessive residual alkali content can negatively impact the lithium-ion battery manufacturing process and battery performance. To inhibit electrolyte corrosion and residual alkali formation, an inert coating is applied to the surface of lithium-rich lithium iron ferrite, which can reduce the residual alkali content to some extent and give it a stable structure.

[0005] However, excessive inert coatings increase the specific surface area, causing the material to absorb more moisture during use, thereby accelerating material deterioration and affecting the capacity of the lithium replenisher, which in turn affects battery performance. Summary of the Invention

[0006] This application provides a lithium replenishing agent and its preparation method, a positive electrode sheet, a separator, a battery, and an electrical device. By doping specific elements into lithium iron ferrite, this application can suppress phase structure changes of lithium iron ferrite, improve the structural stability of lithium iron ferrite positive electrode material, make the crystal lattice less prone to deformation, reduce the generation of residual alkali on the material surface, reduce the impact of residual alkali on the overall performance of the lithium replenishing battery, meet the requirements of power batteries, and at the same time maintain a high battery capacity.

[0007] The first aspect of this application provides a lithium replenishing agent, the lithium replenishing agent comprising Li (5-x) M x Fe (1-y) N yO4, wherein M includes at least one metallic element selected from Al, Mg, Ti, V, Ge, Ga, Rb, and Cs, and N includes at least one metallic element selected from Al, Ti, V, Ge, Cr, Co, Mn, Ni, Cu, Zn, Y, Pd, Ag, Cd, Pt, and Au, and 0.01≤x≤1, 0≤y≤0.5.

[0008] The lithium supplement agent as described above, wherein 0.01≤x≤0.5, 0.1≤y≤0.3.

[0009] The lithium replenishing agent as described above, wherein M includes at least one metallic element selected from Al, Ga, and Ge.

[0010] The lithium supplement described above, wherein M and N are not the same element.

[0011] The lithium replenishing agent as described above, wherein the average particle size of the lithium replenishing agent is 1 to 9 μm.

[0012] The lithium supplement as described above, wherein the lithium supplement comprises Li (5-x) Al x Fe (1-y) N y O4, 0.01≤x≤0.5, 0≤y≤0.5.

[0013] A second aspect of this application provides a method for preparing the lithium supplement agent as described above, comprising the following steps:

[0014] The lithium replenishing agent is obtained by calcining a mixture of lithium-rich lithium iron ferrite and a doped compound in a stoichiometric ratio. The doped compound includes an M source or both an M source and an N source.

[0015] In the preparation method described above, the calcination temperature is 450–950°C and the time is 8–100 hours.

[0016] In the preparation method described above, the particle size of the M source is 0.1 nm to 100 nm.

[0017] In the preparation method described above, the particle size D of the M source is... M Satisfying 0.1nm≤D M <10nm.

[0018] A third aspect of this application provides a positive electrode sheet, including a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector, wherein the positive active material layer includes the lithium supplement agent provided in the first aspect of this application.

[0019] The fourth aspect of this application provides a separator, including a separator substrate and a lithium replenishing layer disposed on one side surface of the separator substrate, wherein the lithium replenishing layer includes the lithium replenishing agent provided in the first aspect of this application.

[0020] The fifth aspect of this application provides a battery, including the positive electrode provided in the third aspect of this application and / or the separator provided in the fourth aspect of this application.

[0021] The sixth aspect of this application provides an electrical device, including the battery provided in the fifth aspect of this application.

[0022] The implementation of this application has at least the following beneficial effects:

[0023] The lithium supplement in this application includes Li (5-x) M x Fe (1-y) N y O4, wherein M includes at least one metallic element selected from Al, Mg, Ti, V, Ge, Ga, Rb, and Cs, and N includes at least one metallic element selected from Al, Ti, V, Ge, Cr, Co, Mn, Ni, Cu, Zn, Y, Pd, Ag, Cd, Pt, and Au, with 0.01 ≤ x ≤ 1 and 0 ≤ y ≤ 0.5. The lithium replenishing agent of this application contains a relatively high amount of lithium, and is a lithium-rich lithium iron ferrite, which can maintain a high battery capacity. Simultaneously, by doping specific elements into the lithium sites of the lithium-rich lithium iron ferrite, the formation energy of oxygen vacancies in the lithium-rich lithium iron ferrite material can be increased, thus enabling O4 to form more oxygen vacancies. 2- The stable presence of y inhibits the reaction that leads to oxygen vacancies, delaying crack formation during material decomposition and effectively improving material stability. It also reduces gas generation during storage. Furthermore, bulk doping makes the structure of lithium-rich lithium iron phosphate materials more compact and reduces specific surface area, thereby reducing the risk of material deterioration due to moisture absorption and ultimately improving battery performance. It is understandable that when y is not 0, i.e., when elements are doped at both lithium and iron sites simultaneously, iron dissolution can be suppressed, improving battery cycle performance. Attached Figure Description

[0024] Figure 1 is a schematic diagram of doping specific elements M and N into the bulk phase of Li5FeO4.

[0025] Figure 2 is a schematic SEM image of the lithium replenishing agent prepared in Example 4;

[0026] Figure 3 is an XRD diagram of the lithium replenishing agent prepared in Example 4;

[0027] Figure 4 shows the charge specific capacity curves of the positive electrode assembled batteries prepared in Examples 3 and 24-26;

[0028] Figure 5 shows the decomposition time of lithium supplements prepared by doping elements with different particle sizes. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, 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.

[0030] To improve the stability and thermal stability of the Li5FeO4 structure, coating is commonly used. While this can suppress electrolyte corrosion and residual alkali formation to some extent, excessive inert coatings can hinder charge transfer in the electrode material, thereby increasing battery polarization and reducing the mass or energy density of the electrode active material. Modified lithium iron ferrite obtained through coating has a larger specific surface area compared to uncoated particles, leading to greater moisture absorption during use and accelerating material degradation, ultimately affecting battery performance.

[0031] Based on this, the first aspect of this application provides a lithium replenishing agent, Li (5-x) M x Fe (1-y) N y O4, wherein M includes at least one metallic element selected from Al, Mg, Ti, V, Ge, Ga, Rb, and Cs, and N includes at least one metallic element selected from Al, Ti, V, Ge, Cr, Co, Mn, Ni, Cu, Zn, Y, Pd, Ag, Cd, Pt, and Au, and 0.01≤x≤1, 0≤y≤0.5.

[0032] As shown in Figure 1, this application dops specific elements into the lithium sites of lithium-rich lithium iron ferrite, increasing the formation energy of oxygen vacancies in the lithium-rich lithium iron ferrite material, thus enabling the O... 2- The stable presence of doped elements inhibits the reaction that leads to oxygen vacancies. By incorporating doping elements into the bulk structure of lithium-rich compounds, the conversion of lithium ions from inactive to active lithium during electrochemical processes is facilitated, effectively improving material stability, reducing the formation of residual alkali insulating layers on the material surface, and resulting in a more compact material structure with a smaller specific surface area. This reduces the risk of material degradation due to moisture absorption, thereby improving the performance of lithium-rich cathode materials. It is understandable that when y is not 0, i.e., doping elements at both lithium and iron sites simultaneously, iron dissolution can be suppressed, thereby improving battery cycle performance.

[0033] Taking Al as an example, where M is the element in the lithium-filled matrix, aluminum doping leads to a decrease in cell parameter a and an increase in c, resulting in a slight decrease in cell volume V. This change causes a decrease in cell parameter a and the interlayer spacing of the transition metal octahedron TMO6. On the other hand, Al... 3+This makes the bonding of TM-O more ionic, enhancing the electrostatic repulsion between oxygen layers, which in turn leads to an increase in interlayer spacing, thus Al 3+ This leads to an increase in the cell parameter c, which is beneficial for the diffusion of lithium ions in the layered structure. When the incorporated aluminum occupies the lithium sites, the resulting aluminum-doped lithium iron phosphate cathode material exhibits high crystal stability, which can suppress side reactions at the electrode interface, enhance its electronic conductivity, reduce residual alkali, and thus reduce the impact of residual alkali on the overall performance of the lithium-ion battery, meeting the requirements of power batteries.

[0034] It is understandable that the type and amount of dopant elements can be adjusted, the doping ratio can be reduced accordingly as the relative molecular mass of the dopant elements increases, and the micropores and porosity created after decomposition will increase accordingly as the doping ratio increases.

[0035] The inventors studied the doping amounts of M and N elements and found that the lithium replenishing effect of the lithium replenishing agent was more excellent when 0.01≤x≤0.5 and 0.1≤y≤0.3. In a preferred embodiment, the average particle size of the lithium replenishing agent is 1–9 μm. A lithium replenishing agent with an average particle size within this range ensures both structural stability and ease of production. For example, the average particle size of the lithium replenishing agent can be any combination of two values ​​from 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or more.

[0036] Generally, the particle size D10 of lithium replenishing agents can be 0.1–1 μm, and D90 can be 30–50 μm. Lithium replenishing agents are in granular form, and their macroscopic appearance is that of powder. The particle size of these powders can specifically be between 0.1 μm and 50 μm.

[0037] In this application, the average particle size of the lithium replenishing agent is also the particle size D50 of the lithium replenishing agent. The particle size D50 represents the particle size that reaches 50% of the volume accumulation from the smallest particle size side in the volume-based particle size distribution of the lithium replenishing agent. D90 represents the particle size that reaches 90% of the volume accumulation from the smallest particle size side in the volume-based particle size distribution of the lithium replenishing agent. D10 represents the particle size that reaches 10% of the volume accumulation from the smallest particle size side in the volume-based particle size distribution of the lithium replenishing agent.

[0038] The particle sizes D10, D50, and D90 of the lithium replenishing agent can be measured using conventional methods in the art, such as laser particle size analyzers or scanning electron microscopes (e.g., scanning electron microscopes (SEM)). For example, after obtaining the lithium replenishing agent, the particle sizes D10, D50, and D90 can be measured using a laser particle size analyzer; after obtaining products such as positive electrode sheets or separators using the lithium replenishing agent, the particle sizes D10, D50, and D90 can be measured using SEM. During testing, at least 50 SEM images can be obtained by scanning the positive electrode sheets or separators using the lithium replenishing agent using SEM. These SEM images are then analyzed using image processing software (e.g., Photoshop (PS)) to measure and statistically analyze the particle sizes of the lithium replenishing agent particles, for example, by using a PS scale to determine the particle sizes D10, D50, and D90 of the lithium replenishing agent. In one specific embodiment, the dopant element M has a mass percentage content of 1% to 10% in the lithium replenisher, preferably 1% to 5%. The doping amount of element M has a certain impact on the structure and performance of the lithium replenisher. Controlling the doping amount of element M within the above range ensures the stability of the material structure and reduces the formation of residual alkali insulating layer on the material surface, thereby improving the performance of the lithium replenisher. For example, the mass percentage content of dopant element M in the lithium replenisher is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two of the above values. The mass percentage content of dopant element N in the lithium replenisher is also 1% to 10%, preferably 1% to 5%. For example, the mass percentage content of dopant element N in the lithium replenisher is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two of the above values. The effect is similar to that of element M.

[0039] In some implementations, Li (5-x) M x Fe (1-y) N y In O4, M includes at least one metal element selected from Al, Ga, and Ge, which can make the crystal structure of the lithium replenishment agent more stable and further reduce the impact of residual alkali on the overall performance of lithium-ion batteries.

[0040] In one specific implementation, Li (5-x) M x Fe (1-y) N y In O4, M and N are not the same element. When doping is performed simultaneously at lithium and iron sites, M and N are not selected as the same element. Different elements can be doped at the lithium and iron sites respectively by controlling the reaction temperature, further ensuring that elements are doped at different positions. In some other embodiments, M and N can be the same element. In one specific embodiment, the lithium supplement includes Li. (5-x) Al xFe (1-y) N y O4, 0.01≤x≤0.5, 0≤y≤0.3. Compared to other doping elements, aluminum-doped lithium supplements have higher conductivity. Aluminum can form fast ion channels, thereby improving the electrical performance of lithium-rich lithium iron ferrite.

[0041] A second aspect of this application provides a method for preparing a lithium supplement, the method comprising the following steps:

[0042] A lithium replenishing agent is obtained by calcining a mixture of lithium-rich lithium iron ferrite and doped compounds in stoichiometric ratio. The doped compounds include M-sources or M-sources and N-sources.

[0043] Specifically, an iron source, a lithium source, a carbon source, and water are mixed and spray-dried to obtain a precursor. The precursor is then sintered and crushed to obtain lithium-rich lithium iron ferrite. This lithium-rich lithium iron ferrite is then mixed with an M source or an M source and an N source in a stoichiometric ratio, ground in a ball mill, and sieved to obtain the target material. The target material is then calcined under an inert gas atmosphere to obtain a lithium supplement. It is understandable that when both an M source and an N source are added simultaneously, the reaction sequence can be controlled by adjusting the calcination temperature, thereby doping at lithium and iron sites respectively.

[0044] This application does not specifically limit the types of iron source, lithium source, M source and N source. Among them, iron source includes but is not limited to one or more of nano iron oxide, Fe2O3, Fe3O4 and FeO; lithium source includes but is not limited to one or more of LiOH, C2H3LiO4, CH3COOLi, LiNO3 and Li2CO3; M source includes but is not limited to one or more of oxides, hydroxides and complex oxides containing element M; N source includes but is not limited to one or more of oxides, hydroxides and complex oxides containing element N.

[0045] For example, when M is aluminum, the source of M can be selected from one or more of Al2O3, Al2O3·TiO2, Al2O3·3H2O, and Al2O3·3SiO2.

[0046] The iron source is preferably nano-iron oxide, which is preferably spherical particles with a particle size of 10–500 nm, more preferably 50–200 nm. The particle size of the nano-iron oxide particles within the above range can form an effective particle size match with the positive electrode active material. For example, the nano-iron oxide particle size is 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, or any two of the above values.

[0047] It is worth mentioning that by using nano-iron oxide as raw material, there is no cation mixing during the preparation process, resulting in a higher material capacity compared to other liquid-phase methods.

[0048] Furthermore, the mass ratio of M source to iron source is 0.001 to 0.5:1, preferably 0.01 to 0.1:1. Controlling the doping amount of M element can effectively reduce the formation of residual alkali insulating layer on the material surface while ensuring the material's structure, thereby reducing the risk of material deterioration due to moisture absorption. For example, the mass ratio of M source to iron source is 0.001:1, 0.002:1, 0.005:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, or any ratio consisting of any value from 0.001 to 0.5 and 1.

[0049] Furthermore, when mixing the iron source, lithium source, carbon source, and water, a dispersant can be added. The dispersant is preferably octyl polyoxyethylene ether, polyethylene glycol octylphenyl ether, or polyvinylpyrrolidone. The mass ratio of the dispersant to the carbon source is 0 to 1:1, preferably 0.01 to 0.1:1. The addition of the dispersant helps to fully disperse and mix the iron source, lithium source, and carbon source, preventing sedimentation during spray drying. For example, the mass ratio of the dispersant to the carbon source can be 0.001:1, 0.002:2, 0.01:1, 0.02:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.5:1, 1:1, or any ratio consisting of 0 to 1 and 1.

[0050] Furthermore, before spray drying, the mixture is continuously stirred, preferably mechanically, to prevent sedimentation and uneven material distribution. The inlet air temperature for spray drying is 120–300°C, preferably 120–260°C, and more preferably 140–180°C. Controlling the inlet air temperature within this range ensures sufficient reaction of the reactants and prevents over-reaction from affecting product performance. For example, the inlet air temperature for spray drying is a range of 120°C, 130°C, 140°C, 150°C, 160°C, 190°C, 200°C, 220°C, 240°C, 250°C, 300°C, or any two of these values. The outlet air temperature is 60–150°C, preferably 70–90°C. For example, the outlet air temperature for spray drying is a range of 60°C, 70°C, 80°C, 90°C, 100°C, 120°C, 150°C, or any two of these values.

[0051] To avoid interference from impurities and moisture in the air, the above calcination process is carried out under an inert atmosphere, wherein the inert gas can be selected from one or more of argon, nitrogen, helium, and neon. Under the protection of the inert gas, side reactions are avoided, resulting in a product with high purity, good air stability, and uniform particle size distribution.

[0052] In one specific embodiment, the calcination temperature of the material is 450–950°C, preferably 700–800°C; the calcination time is 8–100 hours, preferably 10–30 hours. Calcination within the above temperature and time range not only ensures sufficient calcination to obtain a high-purity target product, but also avoids damaging the bulk structure of the target product.

[0053] In one specific embodiment, the particle size of the M source is 0.1 nm to 100 nm, and the preferred particle size of the M source is (D M ) satisfies 0.1nm≤D M <10nm. For example, the particle size of the M source is 0.1nm, 0.5nm, 1nm, 5nm, 10nm, 20nm, 30nm, 50nm, 100nm, or any two of these values. The particle size of the M source affects the polarization of the lithium supplement, thus affecting its decomposition rate. Studies have found that when the particle size of the M source is 0.1nm ≤ D... M The lithium replenisher exhibits optimal performance when the particle size is <10 nm. The N-source particle size also ranges from 0.1 nm to 100 nm, with the preferred N-source particle size D... N Satisfying 0.1nm≤D N <10nm. For example, the particle size of the N source is 0.1nm, 0.5nm, 1nm, 5nm, 10nm, 20nm, 30nm, 50nm, 100nm, or any two of the above values. The effect is similar to that of the M source described above.

[0054] The third aspect of this application provides a positive electrode sheet, including the lithium replenishing agent provided in the first aspect of this application. It is understood that the positive electrode sheet also includes a current collector and a positive electrode active material.

[0055] The positive electrode sheet (also known as the positive electrode sheet) of this application contains the above-mentioned lithium replenishing agent, and therefore it can exert excellent lithium replenishment effect when applied to batteries.

[0056] The positive current collector in this application can be selected from positive current collectors conventionally used in the art, such as aluminum foil.

[0057] The positive electrode active material layer of this application includes components such as positive electrode active material, conductive agent and binder.

[0058] The positive electrode active material includes, but is not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium nickel manganese oxide, and lithium-rich manganese-based materials.

[0059] Conductive agents include, but are not limited to, one or more of conductive carbon black, graphene, acetylene black, Ketjen black, and carbon nanofibers.

[0060] The adhesive includes, but is not limited to, one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, and styrene-butadiene rubber.

[0061] More lithium supplementer results in better lithium supplementation, but excessive lithium supplementer will inevitably lead to a decrease in the content of positive electrode active material, which is detrimental to improving the specific capacity of the positive electrode sheet and the energy density of the battery. Based on the above considerations, the mass content of positive electrode active material in the positive electrode active material layer should be controlled to be no less than 90%, and the mass content of lithium supplementer should be no more than 10%.

[0062] In one specific embodiment, the positive electrode sheet can be prepared by the following method: the positive electrode active material, lithium supplement, conductive agent and binder are dispersed in a solvent in proportion to obtain a slurry, and then the slurry is coated on at least one surface of the positive electrode current collector. After drying, slitting and rolling, the positive electrode sheet can be obtained.

[0063] In this application, the coating, drying, slitting, and rolling processes are all conventional operations in the field and are not particularly limited thereto. The preparation process of the positive electrode sheet will not affect the size or other characteristics of the lithium replenishing agent.

[0064] A fourth aspect of this application provides a separator, including a separator substrate and a lithium replenishing layer disposed on one side surface of the separator substrate, wherein the lithium replenishing layer includes the lithium replenishing agent provided in the first aspect.

[0065] The function of the separator is to separate the positive and negative electrode plates, prevent them from contacting and short-circuiting, and allow lithium ions to pass freely. It should be noted that, in the application of the separator of this application, the side surface with the lithium replenishment layer is positioned opposite the positive electrode so that the lithium replenishment layer can exert its lithium replenishment effect on the positive electrode.

[0066] This application does not specifically limit the type of membrane substrate, which may be selected from porous membranes with good chemical and mechanical stability commonly used in the art, including but not limited to one or more of polypropylene, polyethylene, glass fiber, and nonwoven fabric.

[0067] In one embodiment, the separator of this application can be obtained by coating or depositing a lithium replenishing agent onto the surface of the separator substrate to form a lithium replenishing layer, thereby obtaining a separator with a lithium replenishing layer. The coating can be performed by spraying, spin coating, slurry coating, etc., and the deposition can be performed by physical deposition or chemical deposition. All the processes involved are conventional operations in the art, and these processes do not affect the size or other characteristics of the lithium replenishing agent.

[0068] Considering the differences in the bonding strength between lithium replenishing agents and different types of membrane substrates, an adhesive can be added to the lithium replenishing layer to enhance the bonding strength between the lithium replenishing layer and the membrane substrate, thereby improving its performance.

[0069] The fifth aspect of this application provides a battery, including the positive electrode provided in the third aspect and / or the separator provided in the fourth aspect.

[0070] In addition to the aforementioned positive electrode and / or separator, the battery of this application also includes a negative electrode (also known as a negative electrode sheet) and an electrolyte.

[0071] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector can be selected from negative electrode current collectors conventionally used in the art, such as copper foil. The negative electrode active material layer can also refer to conventional compositions in the art; for example, the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material can be selected from negative electrode active materials conventionally used in the art, including but not limited to one or more of natural graphite, artificial graphite, silicon carbide materials, silicon oxide materials, and hard carbon. The composition of the conductive agent and binder can refer to the types of conductive agents and binders used in the positive electrode sheet, and will not be elaborated here.

[0072] An electrolyte is a medium existing between the positive electrode and the negative electrode for conducting lithium ions. It can be a gel, solid, or liquid electrolyte. This application does not specifically limit the type of electrolyte, which can be selected from gel, solid, or liquid electrolytes commonly used in the art.

[0073] In one specific embodiment, the battery of this application can be prepared by the following method: a bare cell is obtained by winding or stacking a positive electrode sheet, a separator, and a negative electrode sheet, and then the bare cell is packaged into a pre-stamped aluminum-plastic film bag. After the packaged battery is dried at 85°C, electrolyte is injected into the dried battery. After the battery is left to stand, formed, and resealed, the battery of this application is obtained.

[0074] The sixth aspect of this application provides an electrical device including the battery described above. This application does not specifically limit the type of electrical device; it can be any electrical device including the battery, including but not limited to mobile phones, portable devices, laptops, electric bicycles, electric vehicles, electric toys, energy storage devices, etc.

[0075] The following will provide a detailed description of the lithium replenishing agent, its preparation method, and its application through specific embodiments.

[0076] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0077] Example 1

[0078] This embodiment provides a lithium supplement agent, including Li 4.5 Al0.5 FeO4 is prepared by the following steps:

[0079] 1) Lithium hydroxide and nano-iron oxide were mixed at a molar ratio of 5.18:1, and 2% carbon source and an appropriate amount of water were added. The precursor obtained by spray drying was placed in a high-speed mixer for mixing (950 rpm, 12 min). After mixing, the mixture was placed in an inert gas Ar atmosphere for sintering. The temperature was increased to 450℃ at a heating rate of 5℃ / min, and then sintered for 10 minutes. 3 After maintaining an aeration rate of / h for 5 hours, sintering was completed to obtain large solid particles of lithium-rich lithium ferrite. The obtained solid was coarsely crushed and then further crushed using an airflow method to obtain lithium-rich lithium ferrite powder in the target state.

[0080] 2) Alumina with a particle size of 3 nm and lithium iron ferrite powder were placed in a ball mill jar at a mass ratio of 5:95 and ball milled for 3 hours at a speed of 300 rpm with a ball-to-material ratio of 4:1. The ground material was then sieved through a 500-mesh sieve, and the material passing through the sieve was taken as the target material.

[0081] 3) The target material was placed under an inert gas Ar protection environment for calcination. The temperature was increased to 450℃ at a heating rate of 5℃ / min, and then calcined for 10 minutes. 3 The lithium replenishing agent was obtained by maintaining a ventilation rate of / h for 10h and then cooling it after calcination.

[0082] Example 2

[0083] This embodiment provides a lithium supplement agent, including Li 4.88 Al 0.12 FeO4 is prepared in a manner that is basically the same as in Example 1, except that in step 2), the alumina and lithium iron ferrite powder are replaced by a mass ratio of 1.2:98.8.

[0084] Example 3

[0085] This embodiment provides a lithium supplement agent, including Li 4.76 Al 0.24 FeO4 is prepared in a manner that is basically the same as in Example 1, except that in step 2), the alumina and lithium iron ferrite powder are replaced by a mass ratio of 2.4:97.6.

[0086] Example 4

[0087] This embodiment provides a lithium supplement agent, including Li 4.68 Al 0.32 FeO4 is prepared in a manner that is basically the same as in Example 1, except that in step 2), alumina and lithium iron ferrite powder are replaced by a mass ratio of 3.2:96.8.

[0088] Example 5

[0089] This embodiment provides a lithium supplement agent, including Li 4.3 Al 0.7 FeO4 is prepared in a manner that is basically the same as in Example 1, except that in step 2), the alumina and lithium iron ferrite powder are replaced by a mass ratio of 7:93.

[0090] Example 6

[0091] This embodiment provides a lithium supplement agent, including Li4Al1FeO4, whose preparation method is basically the same as that in Example 1, except that in step 2), the alumina and lithium-rich lithium iron ferrite powder are replaced by a mass ratio of 10:90.

[0092] Example 7

[0093] This embodiment provides a lithium supplement agent, including Li 4.5 Mg 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), aluminum oxide is replaced with magnesium oxide.

[0094] Example 8

[0095] This embodiment provides a lithium supplement agent, including Li 4.5 Ti 0.5 FeO4 is prepared in a manner that is basically the same as in Example 1, except that in step 2), aluminum oxide is replaced with titanium oxide.

[0096] Example 9

[0097] This embodiment provides a lithium supplement agent, including Li 4.5 Cs 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), aluminum oxide is replaced with cesium oxide.

[0098] Example 10

[0099] This embodiment provides a lithium supplement agent, including Li 4.5 Ga 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), aluminum oxide is replaced with gallium oxide.

[0100] Example 11

[0101] This embodiment provides a lithium supplement agent, including Li 4.5 Ge 0.5The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), gallium oxide is replaced with germanium oxide.

[0102] Example 12

[0103] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.9 Cr 0.1 O4, the preparation method of which includes the following steps:

[0104] 1) Lithium hydroxide and nano-iron oxide were mixed at a molar ratio of 5.18:1, and 2% carbon source and an appropriate amount of water were added. The precursor obtained by spray drying was placed in a high-speed mixer for mixing (950 rpm, 12 min). After mixing, the mixture was placed in an inert gas Ar atmosphere for sintering. The temperature was increased to 450℃ at a heating rate of 5℃ / min, and then sintered for 10 minutes. 3 After maintaining an aeration rate of / h for 5 hours, sintering was completed to obtain large solid particles of lithium-rich lithium ferrite. The obtained solid was coarsely crushed and then further crushed using an airflow method to obtain lithium-rich lithium ferrite powder in the target state.

[0105] 2) Alumina with a particle size of 3 nm and lithium iron ferrite powder were placed in a ball mill jar at a mass ratio of 5:95 and ball milled for 3 hours at a speed of 300 rpm with a ball-to-material ratio of 4:1. The ground material was then sieved through a 500-mesh sieve, and the material passing through the sieve was taken as the target material.

[0106] 3) The target material was placed under an inert gas Ar protection environment for calcination. The temperature was increased to 850℃ at a heating rate of 5℃ / min, and then calcined at a temperature of 10m. 3 After calcination, the temperature was lowered to 750℃ and chromium trioxide was added. The mass ratio of chromium trioxide to lithium iron ferrite powder was 0.1:99.9. The mixture was then calcined at a ventilation rate of 10 m³ / h for 10 h. 3 After maintaining a ventilation rate of / h for 10h, the lithium replenishing agent was obtained by cooling after calcination.

[0107] Example 13

[0108] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.8 Cr 0.2 O4, the preparation method of which is basically the same as that in Example 12, the difference is that in step 3), chromium trioxide and lithium iron ferrite powder are replaced by a mass ratio of 0.2:99.8.

[0109] Example 14

[0110] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.7 Cr 0.3 O4, the preparation method of which is basically the same as that in Example 12, the difference is that in step 3), chromium trioxide and lithium iron ferrite powder are replaced by a mass ratio of 0.3:99.7.

[0111] Example 15

[0112] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.5 Cr 0.5 O4 is prepared in a manner that is basically the same as in Example 12, except that in step 3), chromium trioxide and lithium iron ferrite powder are replaced by a mass ratio of 0.5:99.5.

[0113] Example 16

[0114] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.9 Co 0.1 O4 is prepared in a manner that is basically the same as in Example 12, except that in step 3), chromium trioxide is replaced with cobalt trioxide.

[0115] Example 17

[0116] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 Fe 0.9 Ge 0.1 O4 is prepared in a manner that is basically the same as in Example 12, except that in step 3), chromium trioxide is replaced with germanium dioxide.

[0117] Example 18

[0118] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 0.1 nm.

[0119] Example 19

[0120] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 1 nm.

[0121] Example 20

[0122] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 10 nm.

[0123] Example 21

[0124] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 50 nm.

[0125] Example 22

[0126] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 100nm.

[0127] Example 23

[0128] This embodiment provides a lithium supplement agent, including Li 4.5 Al 0.5 The preparation method of FeO4 is basically the same as that in Example 1, except that in step 2), the particle size of alumina is replaced with 200 nm.

[0129] Example 24

[0130] This embodiment provides a lithium supplement agent, including Li 4.76 Ga 0.24 The preparation method of FeO4 is basically the same as that in Example 3, except that in step 2), aluminum oxide is replaced with gallium oxide.

[0131] Example 25

[0132] This embodiment provides a lithium supplement agent, including Li 4.76 Co 0.24 FeO4 is prepared in a manner that is basically the same as in Example 3, except that in step 2), aluminum oxide is replaced with cobalt trioxide.

[0133] Example 26

[0134] This embodiment provides a lithium supplement agent, including Li 4.76 Cr 0.24The preparation method of FeO4 is basically the same as that in Example 3, except that in step 2), aluminum oxide is replaced with chromium trioxide.

[0135] Comparative Example 1

[0136] This comparative example provides a lithium supplement agent comprising Li5FeO4, the preparation method of which includes the following steps:

[0137] Lithium hydroxide and nano-iron oxide were mixed at a molar ratio of 5.18:1, followed by the addition of 2% carbon source and an appropriate amount of water. The mixture was then spray-dried, and the resulting precursor was placed in a high-speed mixer for mixing (950 rpm, 12 min). After mixing, the mixture was calcined under an inert Ar atmosphere. The temperature was increased to 450℃ at a rate of 5℃ / min, and then calcined for 10 minutes. 3 After maintaining a ventilation rate of / h for 5h, calcination was completed to obtain large solid particles of lithium iron ferrite rich in lithium, obtained from a single calcination. The obtained solid was coarsely crushed and then further crushed using an airflow method to obtain the lithium supplement Li5FeO4.

[0138] Comparative Example 2

[0139] This embodiment provides a lithium supplement agent, including Li3Al2Fe 0.9 Cr 0.1 O4 is prepared in a manner that is basically the same as in Example 12, except that in step 2), the alumina and lithium iron ferrite powder are replaced by a mass ratio of 20:80.

[0140] Test case

[0141] I. The following performance tests were conducted on the lithium supplements of the above embodiments and comparative examples:

[0142] 1. The particle sizes D10, D50 (average particle size), and D90 of the lithium supplements in Examples 1 to 26, Comparative Example 1 and Comparative Example 2 were measured by a laser particle size analyzer. The particle sizes D50 were all between 1 μm and 9 μm, D10 were between 0.1 and 1 μm, and D90 were between 30 and 50 μm.

[0143] 2. Scanning electron microscopy test

[0144] Test method: Take an appropriate amount (approximately 0.5g) of the lithium replenishing agent prepared in Example 4 and place it in a sample tube. Use double-sided conductive carbon tape to fix the sample on a special sample tray, ensuring that the sample is evenly distributed and firmly fixed to prevent it from falling off during operation. Place the prepared sample tray into the sample chamber of a scanning electron microscope and maintain the vacuum level to the set requirements. Adjust the focus and aperture of the SEM to obtain a clear sample image. The test results are shown in Figure 2.

[0145] 3. XRD test

[0146] Test method: After storing the lithium replenishing agents prepared in Example 4 and Comparative Example 1 in a desiccator for 24 hours, take 0.5g of the sample, grind it thoroughly in a mortar, pour it into the sample slot in the sample holder, and level it. Set the X-ray source to a copper target (Cu-Kα radiation) with a wavelength of [wavelength missing]. The scanning range of the goniometer was adjusted from 2θ = 10° to 80°, and the scanning speed was approximately 1° / min. The test results are shown in Figure 3.

[0147] Since Al site doping is related to the residual alkali content and the moisture absorption rate, tests were conducted on Examples 1-11 and 18-26.

[0148] 4. Residual alkali content test

[0149] The lithium supplementing agents from Examples 1-26 and Comparative Examples 1-2 were thoroughly mixed and ground with polyvinylidene fluoride (PVDF) and carbon nanotubes at a mass ratio of 8:1:1. The resulting slurry was coated onto a 300mm*1000mm aluminum foil with a thickness of 200μm as the positive electrode material for lithium-ion batteries. The obtained positive electrode material was cut into 60mm*70mm positive electrode sheets, and the positive electrode sheets were placed in a constant temperature and humidity chamber with a humidity of 60% for 0, 5, and 10 minutes, respectively. The residual alkali content of the positive electrode sheets placed under different environments was tested.

[0150] Test method: Methanol was used as the solvent to dissolve the residual alkali on the surface of the lithium supplement to obtain the test solution. Potentiometric titration was performed on the test solution using a 0.01M HCl standard solution to obtain the titration curve. The contents of LiOH and Li₂CO₃ in the lithium supplement were then measured. The test results are shown in Table 1.

[0151] 5. Moisture absorption rate

[0152] Test method: 0.2 g of lithium supplementer from Examples 1-26 and Comparative Examples 1-2 were taken respectively and dried in a vacuum oven at (60±1)℃ and a relative vacuum of -100Pa for 2 hours. The samples were then placed in a constant temperature and humidity chamber with a humidity of 60% and a room temperature of 25℃ for moisture absorption rate testing, with a test interval of 20 min. The moisture absorption rate of the material was obtained according to the formula v=(m1-m2) / t, where m1 and m2 are the mass of the material before and after the test, respectively, and t is the test interval time, which is 20 min here. The test results are shown in Table 1.

[0153] 6. Inductively Coupled Plasma Emission Spectroscopy (ICP): The negative electrode was tested after 2000 cycles.

[0154] 1) Scrape off the graphite from the target negative electrode and grind it to a particle size of 200 mesh.

[0155] 2) Place 0.2g of dried graphite in a container, add 15ml of hydrochloric acid solution to the dried scandium concentrate, heat to boiling, then add 5ml of nitric acid solution and 5ml of perchloric acid solution, heat to dissolve, and after the white fumes of perchloric acid are exhausted, concentrate to 2ml, cool, add 10ml of hydrochloric acid solution, continue cooling, filter, transfer the solution to a 100mL volumetric flask, make up to 100mL, shake well, filter to obtain the sample solution.

[0156] 3) The element content in the test solution sample was detected by inductively coupled plasma atomic emission spectrometry (ICP-AES). The operating parameters of the ICP-AES were as follows: RF power of 1.2KW, auxiliary gas flow rate of 1.0L / min, nebulizer flow rate of 0.6L / min, stabilization time of 15s, rise delay of 10s, and pump speed of 12rpm.

[0157] II. After preparing the lithium supplementation agent from Examples 1-26 and Comparative Examples 1-2 as a positive electrode sheet, it is assembled with a negative electrode sheet, electrolyte, and separator according to the following method to obtain a lithium-ion battery:

[0158] 1) The lithium supplement agent was mixed with conductive carbon black and PVDF at a weight ratio of 96%:2%:2%, and dispersed to obtain a positive electrode slurry. This slurry was then coated onto an aluminum foil current collector, with a positive electrode surface density of 4.12 g / cm³. 3 The positive electrode sheet is prepared by rolling.

[0159] 2) Artificial graphite, styrene-diene rubber, sodium carboxymethyl cellulose, and conductive carbon black are mixed in a weight ratio of 94%:3%:2%:1%. The mixture is dispersed in water and then mixed using a double planetary mixer to obtain a negative electrode slurry. This slurry is coated onto a copper current collector, followed by rolling and drying to obtain the negative electrode sheet.

[0160] 3) Assemble the positive electrode, negative electrode and separator into a lithium-ion battery and inject a non-aqueous electrolyte, wherein the electrolyte is 1 mol LiPF6 dissolved in a solvent with a mass ratio of DMC / EMC / DEC of 1:1:1.

[0161] The following performance tests were performed on the lithium-ion batteries assembled above:

[0162] 1. Charging specific capacity

[0163] Test method: After standing at 25℃ for 4 hours, the first charge capacity test was conducted. The test conditions were: 0.1C charging to 4.55V, constant voltage charging to 0.025C, and the specific charge capacity of the battery was recorded. The test results are shown in Figure 4.

[0164] 2. Charging time

[0165] Test method: Charge the battery at 0.05C to 4.4V, then charge it at a constant voltage to 0.001C and record the charging time, which is the decomposition time of the lithium additive. The test results are shown in Figure 5.

[0166] Table 1

[0167] As shown in Figure 2, the lithium supplement doped with aluminum can be seen to have obvious dot-like distributions on the surface in the scanning electron microscope. The dots can be identified by EDS test in the scanning electron microscope as the distribution of aluminum in lithium-rich lithium iron ferrite, thus proving that aluminum has been successfully doped into lithium-rich lithium iron ferrite.

[0168] As shown in Figure 3, Comparative Example 1 is a lithium supplement without any doping, while Example 4 is a lithium supplement doped with a certain amount of aluminum. The XRD pattern shows that compared to the undoped lithium supplement, the peak position of the aluminum-doped lithium supplement is significantly shifted to the right, and the peak intensity also changes significantly, indicating a change in the crystal structure and the formation of Li. (5-x) Al x FeO4.

[0169] The following conclusions can be drawn from Table 1:

[0170] A comparison of Examples 1-17 and Comparative Example 1 shows that doping specific elements into lithium iron ferrite increases the formation energy of oxygen vacancies in the lithium iron ferrite material, thus increasing the oxygen vacancy formation energy. 2- The stable existence of the material inhibits the reaction of oxygen escaping and forming oxygen vacancies, effectively improving the stability of the material, reducing the formation of residual alkali insulating layer on the material surface, and making the material structure more compact through bulk doping. The moisture absorption rate is significantly reduced, reducing the risk of material deterioration caused by moisture absorption and improving the performance of lithium-rich cathode materials.

[0171] A comparison of Examples 1-6 and Comparative Example 1 shows that the cathode material prepared when 0.01≤x≤1 has a more significant decrease in residual alkali content and moisture absorption rate compared to the cathode material prepared when x>1. Furthermore, when 0.01≤x≤0.5, the cathode material has a more stable structure, and the moisture absorption rate and residual alkali content are lower than when 0.5<x≤1.

[0172] Furthermore, in Comparative Example 2, when x is too large, the specific capacity of the battery deteriorates severely. In contrast to Comparative Example 2, Examples 1 to 26, by controlling 0.01≤x≤1, can significantly improve the specific capacity while reducing the residual alkali content and moisture absorption rate, thus achieving a balance between the low moisture content, low residual alkali content, and high capacity of the lithium replenishing agent and improving battery performance.

[0173] A comparison of Examples 1 with Examples 7-11 and Examples 3 with Examples 24-26 shows that when the same amount of elements are doped at the lithium site, the cathode material prepared by doping with aluminum is more stable than that prepared by doping with other elements at the lithium site, and has a lower moisture absorption rate and residual alkali content.

[0174] A comparison of Examples 1 and 12-17 shows that, compared to cathode materials doped only at lithium sites, cathode materials doped at both lithium and iron sites have lower ICP values, thus suppressing the dissolution of iron. Furthermore, when 0.1 ≤ y ≤ 0.3, the ICP of cathode materials doped at both lithium and iron sites decreases further, resulting in a more significant effect in suppressing the dissolution of iron.

[0175] As shown in Figure 4, a comparison of Examples 3 and 24-26 reveals that, when batteries with gallium, chromium, and cobalt as dopants and aluminum as dopants were measured at the same doping level, the battery with aluminum as the dopant exhibited a better specific charging capacity than the other three types. (The figure shows that, compared to aluminum doping with gallium and cobalt, the lithium replenishment agent using aluminum can release more capacity during charging. This is because gallium and cobalt have lower conductivity than aluminum. Furthermore, gallium and cobalt have larger relative molecular masses, and under the same doping level, aluminum can provide more conductive sites, which helps to fully release the capacity.)

[0176] As shown in Figure 5, a comparison between Examples 1 and Examples 18-21 reveals that the decomposition time of the lithium replenishment agent increases with the increase of the dopant particle size. This is because the particle size of the dopant element is related to the polarization of the finished lithium replenishment agent. The smaller the particle size, the smaller the polarization of the lithium replenishment agent (smaller battery polarization), and the shorter the corresponding decomposition time; conversely, the larger the particle size, the greater the polarization of the lithium replenishment agent, and the longer the decomposition time. Table 1 shows that the dopant particle size has no significant effect on the moisture absorption rate and residual alkali content of the cathode material.

[0177] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A lithium supplement agent, wherein, The lithium supplement includes Li (5-x) M x Fe (1-y) N y O4, wherein M includes at least one metallic element selected from Al, Mg, Ti, V, Ge, Ga, Rb, and Cs, and N includes at least one metallic element selected from Al, Ti, V, Ge, Cr, Co, Mn, Ni, Cu, Zn, Y, Pd, Ag, Cd, Pt, and Au, and 0.01≤x≤1, 0≤y≤0.

5.

2. The lithium supplement agent according to claim 1, wherein, 0.01≤x≤0.5, 0.1≤y≤0.

3.

3. The lithium supplement agent according to claim 1, wherein, M includes at least one metallic element selected from Al, Ga, and Ge.

4. The lithium supplement agent according to any one of claims 1-3, wherein, M and N are not the same element.

5. The lithium supplement agent according to any one of claims 1-4, wherein, The average particle size of the lithium supplement is 1–9 μm.

6. The lithium supplement agent according to claim 1, wherein, The lithium supplement includes Li (5-x) Al x Fe (1-y) N y O4, 0.01≤x≤0.5, 0≤y≤0.

5.

7. A method for preparing the lithium supplement agent according to any one of claims 1-6, wherein, Includes the following steps: The lithium replenishing agent is obtained by calcining a mixture of lithium-rich lithium iron ferrite and a doped compound in a stoichiometric ratio. The doped compound includes an M source or both an M source and an N source.

8. The preparation method according to claim 7, wherein, The calcination temperature is 450–950°C, and the time is 8–100 hours.

9. The preparation method according to claim 7 or 8, wherein, The particle size of the M source is 0.1 nm to 100 nm.

10. The preparation method according to any one of claims 7-9, wherein, The particle size D of the M source M Satisfying 0.1nm≤D M <10nm.

11. A positive electrode plate, wherein, It includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector, wherein the positive active material layer includes the lithium supplement agent according to any one of claims 1-6.

12. A diaphragm, wherein, It includes a membrane substrate and a lithium replenishing layer disposed on one side surface of the membrane substrate, wherein the lithium replenishing layer includes the lithium replenishing agent according to any one of claims 1-6.

13. A battery, wherein, Includes the positive electrode sheet as described in claim 11 and / or the separator as described in claim 12.

14. An electrical appliance, wherein, Includes the battery as described in claim 13.

Images