Positive electrode lithium-supplementing agent, preparation method therefor, positive electrode sheet, battery, and electrical device

Abstract

The present application provides a positive electrode lithium-supplementing agent, a preparation method therefor, a positive electrode sheet, a battery, and an electrical device. The positive electrode lithium-supplementing agent of the present application comprises a lithium-supplementing core and a carbon coating layer coated on the surface of the lithium-supplementing core. The Raman spectrum of the positive electrode lithium-supplementing agent has a G peak having a shift interval of 1560-1580 cm-1, a D peak having a shift interval of 1350-1370 cm-1, and a 1 peak having a shift interval of 655-675 cm-1. The peak intensity IG of the G peak, the peak intensity ID of the D peak, and the peak intensity I1 of the 1 peak satisfy: 0.85<IG / ID<1.25, 9<IG / I1<50, and 9<ID / I1<50. The carbon coating layer of the positive electrode lithium-supplementing agent of the present application is dense and uniform and has excellent conductivity, and can better isolate the lithium-supplementing core from air, thereby improving the environmental resistance of the positive electrode lithium-supplementing agent, reducing the content of residual bases on the surface, and at the same time greatly improving the conductivity of the positive electrode lithium-supplementing agent, which is beneficial to the full utilization of the lithium-supplementing capacity.

Description

Positive electrode lithium replenishing agent and its preparation method, positive electrode sheet, battery and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202411555645.1, filed on October 31, 2024, entitled "Lithium Supplement Agent and Preparation Method Thereof, Positive Electrode, Battery and Electrical Device", the entire contents of which are incorporated herein by reference.

[0002] This application claims priority to Chinese Patent Application No. 202411756487.6, filed on November 28, 2024, entitled "Cathode Lithium Supplement Agent and Preparation Method Thereof, Cathode Electrode, Battery and Electrical Device", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a positive electrode lithium replenishing agent and its preparation method, a positive electrode sheet, a battery, and an electrical device. Background Technology

[0004] Lithium-ion batteries possess characteristics such as high operating voltage, high specific energy, small size, light weight, and long cycle life, making them a focal point of competition in the automotive industry. With the continuous development of lithium-ion batteries in portable electronic devices, electric bicycles, and electric vehicles, the requirements for their energy density and other performance aspects are becoming increasingly stringent. Lithium loss is the direct cause of battery performance degradation. Currently, lithium replenishment at the positive electrode can compensate for the lithium source consumed during battery charging and discharging, thereby improving the battery's energy density and cycle life. Commonly used positive electrode lithium replenishing agents are lithium-rich oxides, which release lithium ions during battery formation to compensate for the efficiency loss during the first charge and discharge of the negative electrode. However, positive electrode lithium replenishing agents have poor environmental tolerance, easily absorb moisture, and have high residual alkali content, which is detrimental to battery use. Summary of the Invention

[0005] This application provides a positive electrode lithium replenisher, a positive electrode sheet, a battery, and an electrical device. The core surface of the positive electrode lithium replenisher of this application includes a dense, uniform, and highly conductive carbon coating layer. This coating layer can better isolate the lithium replenishing core from the air, improve the environmental tolerance of the positive electrode lithium replenisher, reduce the surface residual alkali content, reduce side reactions during lithium replenishment, and significantly improve the conductivity of the positive electrode lithium replenisher, which is conducive to the full utilization of the lithium replenishment capacity.

[0006] In a first aspect, this application provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core;

[0007] The Raman spectrum of the positive electrode lithium supplement has a shift range of 1560–1580 cm⁻¹. -1The G peak and displacement range are 1350–1370 cm. -1 The D peak and displacement range are 655–675 cm. -1 Peak 1;

[0008] Among them, the peak intensities IG of peak G, ID of peak D, and I1 of peak 1 satisfy: 0.85 <IG / ID<1.25,9<IG / I1<50,9<ID / I1<50。

[0009] The positive electrode lithium replenishing agent as described above is obtained by sintering a mixture including a lithium replenishing core, a carbon source, and a coating additive.

[0010] The coating additive includes compounds capable of thermally decomposing to generate gaseous carbohalogens and halogen radicals, wherein the thermal decomposition temperature is not higher than the sintering temperature.

[0011] And / or, the chemical composition of the lithium-supplementing core is Li a M b O c M includes one or more of Fe, Ni, Mn, Cu, Zn, Co, Cr, Zr, Sb, Ti, V, Mo, and Sn, where 1 < a ≤ 8, 0 < b ≤ 1, and 0 < c < 7.

[0012] The positive electrode lithium replenisher as described above, wherein the molecular weight of the coating additive is <600;

[0013] And / or, the coating additive includes one or more of hexachlorobenzene, hexabromobenzene, chlorobenzene, bromobenzene, dichlorobenzene, and dibromobenzene;

[0014] And / or, the carbon source includes one or more of carbon black, graphene, carbon nanotubes, fullerene, sucrose, glucose, pitch, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, anthracene, or aniline; and / or, the mass ratio of the lithium-supplementing core, the carbon source, and the coating additive is 1:x:y, 0 <x<10%,0<y<10%。

[0015] The positive electrode lithium replenishing agent as described above, wherein the D50 particle size of the positive electrode lithium replenishing agent is 10-30 μm;

[0016] And / or, the thickness of the carbon coating layer is 100–200 nm; and / or, the specific surface area of ​​the positive electrode lithium supplement is 0.3–0.8 m². 2 / g.

[0017] Secondly, this application also provides a method for preparing the positive electrode lithium replenishing agent described in the first aspect, comprising the following steps:

[0018] The lithium-replenishing core, carbon source, and coating additives are mixed to obtain a mixture; the mixture is then sintered to obtain a positive electrode lithium-replenishing agent.

[0019] The coating additive includes compounds capable of thermally decomposing to generate gaseous carbohalogen free radicals and halogen free radicals, wherein the thermal decomposition temperature is not higher than the sintering temperature.

[0020] In the preparation method described above, the sintering treatment is carried out at a temperature of 80–1000°C for 3–15 hours.

[0021] Thirdly, this application also provides a positive electrode lithium replenishing agent, comprising: a core, the core comprising a lithium replenishing core; and a coating layer, the coating layer covering the core, the coating layer comprising an oxygen-deficient compound.

[0022] The positive electrode lithium replenisher as described above, wherein the oxygen-deficient compound includes at least one of an oxygen-deficient metal compound and an oxygen-deficient nonmetal compound.

[0023] The positive electrode lithium replenisher as described above, wherein the oxygen-deficient metal compound includes Al2O 3-x MgO 1-y and TiO 2-z At least one of them; wherein, 0 <x<3,0<y<1,0<z<2;

[0024] And / or, the oxygen-deficient nonmetallic compound includes SiO₂ 2-a ; among which, 0 <a<2。

[0025] As described above, the positive electrode lithium replenisher, based on the positive electrode lithium replenisher, has the following mass percentage m1 of the oxygen-deficient compound: 0 < m1 ≤ 10%; preferably, the mass percentage m1 of the oxygen-deficient compound has the following mass percentage m1: 0.1% < m1 ≤ 5%.

[0026] And / or, the D50 of the oxygen-deficient compound is 20 nm to 200 nm;

[0027] And / or, the D of the lithium-filled core 50 The thickness is 1μm to 20μm; and / or, the lithium-replenishing core comprises a binary lithium compound or a ternary lithium compound;

[0028] And / or, the lithium replenishment core includes at least one of Li5FeO4, Li2NiO2, and Li2O2;

[0029] And / or, the coating layer further includes a conductive material; the conductive material includes at least one of conductive carbon material and conductive non-carbon material.

[0030] In the positive electrode lithium replenisher described above, the water contact angle of the conductive material is 90°≤θ≤160°; and / or the mass percentage m2 of the conductive material satisfies: 0<m2≤10%.

[0031] Fourthly, this application also provides a method for preparing the positive electrode lithium replenishing agent as described in the third aspect, comprising:

[0032] A mixture is obtained by mixing a lithium-replenishing core and an oxygen-deficient compound, and the mixture is then heat-treated to obtain the positive electrode lithium replenishing agent.

[0033] The preparation method described above, wherein the step of mixing the lithium-filled core and the oxygen-deficient compound to obtain a mixture further includes the addition of a conductive material; and / or, the heat treatment control parameters include:

[0034] The heat treatment temperature is 20℃~200℃, and / or the heat treatment time is 1h~6h.

[0035] The preparation method described above, wherein the oxygen-deficient compound is prepared by the following method:

[0036] The oxygen-deficient compound is obtained by mixing a metal oxide or non-metal oxide with a reducing agent and then annealing it; wherein the annealing parameters include at least one of the following:

[0037] (a) The annealing temperature is 500℃~1000℃;

[0038] (b) Annealing time is 6h to 15h;

[0039] (c) Annealing is carried out under an inert atmosphere.

[0040] Fifthly, this application also provides a positive electrode sheet, comprising 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 comprises the positive lithium supplement agent described in the first aspect, or the positive lithium supplement agent prepared by the preparation method described in the second aspect, or the positive lithium supplement agent described in the third aspect, or the positive lithium supplement agent prepared by the preparation method described in the fourth aspect.

[0041] The positive electrode sheet described above further includes a positive electrode active material; the positive electrode active material includes LiFePO4 and LiNi. c Co d Mn 1-c-d O2, wherein at least one of 0.3≤c<1 and 0≤d≤0.5.

[0042] In a sixth aspect, the present application also provides a battery, including the above-mentioned positive electrode sheet.

[0043] In a seventh aspect, the present application also provides an electrical device, including the above-mentioned battery.

[0044] The implementation of the present application has at least the following beneficial effects:

[0045] 1) The positive electrode lithium supplement agent of the present application includes a lithium supplement core and a carbon coating layer coated on the surface of the lithium supplement core. In the Raman spectrum of the positive electrode lithium supplement agent, there is a G peak with a displacement range of 1560 - 1580 cm -1 a D peak with a displacement range of 1350 - 1370 cm -1 and a 1 peak with a displacement range of 655 - 675 cm -1 By defining that the peak intensity IG of the G peak, the peak intensity ID of the D peak, and the peak intensity I1 of the 1 peak satisfy: 0.85 < IG / ID < 1.25, 9 < IG / I1 < 50, 9 < ID / I1 < 50, a suitable content of bulk carbon with a high degree of graphitization and edge carbon with a high degree of disorder is distributed on the surface of the lithium supplement core, forming a dense, uniform and excellent conductive carbon coating layer. This can better isolate the lithium supplement core from air, improve the environmental tolerance of the positive electrode lithium supplement agent, reduce the surface residual alkali content, and at the same time greatly improve the conductivity of the positive electrode lithium supplement agent, which is beneficial to the full play of the lithium supplement capacity.

[0046] 2) The preparation method of the positive electrode lithium supplement agent provided by the present application prepares the positive electrode lithium supplement agent by sintering after mixing the lithium supplement core, carbon source and coating additive; among them, the coating additive includes a compound that can thermally decompose to generate gaseous carbon halogen radicals and halogen radicals, and the thermal decomposition temperature is not higher than the heat treatment temperature. During the heat treatment process, the coating additive can thermally decompose to generate gaseous carbon halogen radicals (CX·) and halogen radicals (X·). The highly active halogen radicals can combine with the carbon source material to generate more gaseous carbon halogen radicals, greatly increasing the concentration of gaseous carbon halogen radicals. At this time, the lithium supplement core is exposed to a high-concentration gaseous carbon halogen radical atmosphere. The solid-gas two-phase ensures their full contact. After the gaseous carbon halogen radicals undergo dehalogenation reaction on the surface of the lithium supplement core, a dense and uniform carbon coating layer can be in-situ generated.

[0047] 3) Since the positive electrode sheet and battery provided by the present application include the above-mentioned positive electrode lithium supplement agent, they can supplement the active lithium loss during the first charge-discharge process and the cycle process of the battery, enabling the battery to have a higher first-cycle Coulomb efficiency and cycle performance. Description of the Drawings

[0048] FIG. 1 is a schematic structural diagram of a traditional positive electrode lithium supplement agent;

[0049] Figure 2 is a schematic diagram of the structure of a positive electrode lithium replenishing agent according to an embodiment of this application;

[0050] Figure 3 shows the Raman spectrum of the positive electrode lithium replenishment agent in Example 11;

[0051] Figure 4 is a SEM image of the positive electrode lithium replenishment agent of Example 1;

[0052] Figure 5 shows the SEM image of the positive electrode lithium replenishment agent of Comparative Example 1.

[0053] Figure labeling: 11-Lithium core; 22-Carbon coating layer; 33-Pore. Detailed Implementation

[0054] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0055] Traditional cathode lithium replenishers, such as Li5FeO4, Li2NiO2, Li6CoO4, and Li2O2, have large band gaps, poor conductivity, and are unstable in the environment. Therefore, conductive carbon materials are usually used to coat their surfaces. The coating layer improves the conductivity of the lithium replenisher and also effectively isolates the lithium replenishing active material from the air, preventing it from reacting and deteriorating with moisture and carbon dioxide in the air. However, the traditional coating layer has poor density, which limits its protective effect on the internal lithium replenishing active material. Figure 1 is a schematic diagram of a traditional cathode lithium replenisher. As shown in Figure 1, the lithium replenisher includes a lithium replenishing core 11 and a carbon coating layer 22. The carbon coating layer 22 also includes pores 33 penetrating the surface of the lithium replenishing core. The presence of pores 33 means that the lithium replenishing core still has a certain contact area with the air, which limits the isolation and protection effect of the carbon coating layer. Ultimately, the residual alkali content on the surface of the cathode lithium replenisher is still high, the conductivity of the material is still low, and there is still room for improvement in lithium replenishment capacity.

[0056] Based on this, this application provides a positive electrode lithium replenishing agent. Figure 2 is a schematic diagram of the structure of a positive electrode lithium replenishing agent according to an embodiment of this application. As shown in Figure 2, the positive electrode lithium replenishing agent of this application includes a lithium replenishing core 11 and a carbon coating layer 22 covering the surface of the lithium replenishing core; wherein, the Raman spectrum of the positive electrode lithium replenishing agent has a shift range of 1560-1580 cm⁻¹. -1 The G peak and displacement range are 1350–1370 cm. -1 The D peak and displacement range are 655–675 cm. -1 Peak 1;

[0057] Among them, the peak intensity IG of the G peak, the peak intensity ID of the D peak, and the peak intensity I1 of the 1 peak satisfy: 0.85 < IG / ID < 1.25, 9 < IG / I1 < 50, 9 < ID / I1 < 50.

[0058] Among them, the G peak is the sp 2 hybridization peak of carbon, mostly the peak of bulk carbon. Bulk carbon refers to the carbon atoms inside the carbon crystal, and their surroundings are saturated and paired. The more bulk carbon there is, the higher the graphitization degree of the carbon coating layer, the larger the sheet layer, the higher the two-dimensional plane spreading degree, and the higher the conductivity. However, if the sheet layer is too large, it is not conducive to the dense coating of the carbon material on the surface of the lithium supplement core; the D peak is the peak of carbon in the form of edge carbon and sp 3 hybridization. Among them, edge carbon refers to the carbon at the edge of the carbon crystal, and there are unsaturated pairs around it. The higher the D peak intensity, the higher the degree of disorder of the carbon material, indicating that the carbon material tends more towards a point-like structure, and the smaller the sheet layer, the more conducive it is to the dense coating of the carbon material on the surface of the lithium supplement core. However, if the degree of disorder is too high, it is also not conducive to the carbon coating layer to exhibit good conductivity; the 1 peak is the bond vibration peak of the metal element and oxygen in the lithium supplement agent core material, and its peak intensity reflects the exposure degree of the lithium supplement core. The higher the peak intensity of the 1 peak, the more incomplete the coating of the carbon coating layer. If the peak intensity of the 1 peak is too low, it indicates that there is too much carbon material on the outer layer, resulting in an increase in the resistance to lithium ion deintercalation and affecting the electrochemical properties of the material.

[0059] In this application, by controlling the peak intensity IG of the G peak, the peak intensity ID of the D peak, and the peak intensity I1 of the 1 peak in the Raman spectrogram of the positive electrode lithium supplement agent to satisfy: 0.85 < IG / ID < 1.25, 9 < IG / I1 < 50, 9 < ID / I1 < 50, a suitable content of bulk carbon with a high graphitization degree and edge carbon with a high degree of disorder is distributed on the surface of the lithium supplement core, forming a dense, uniform and excellent conductive carbon coating layer, which can better isolate the lithium supplement core from air, improve the environmental tolerance of the positive electrode lithium supplement agent, reduce the surface residual alkali content, and at the same time greatly improve the conductivity of the positive electrode lithium supplement agent, which is beneficial to the full play of the lithium supplement capacity.

[0060] As a preferred implementation manner, the positive electrode lithium supplement agent is obtained by sintering a mixture including a lithium supplement core, a carbon source, and a coating additive. The coating additive includes a compound that can thermally decompose to generate gaseous carbon halogen radicals and halogen radicals, and the temperature of the thermal decomposition is not higher than the temperature of the sintering treatment.

[0061] During the sintering process, the coating additives can thermally decompose to generate gaseous carbohalogens (CX·) and halogen radicals (X·). The highly active halogen radicals can combine with the carbon source material to generate more gaseous carbohalogens, greatly increasing the concentration of gaseous carbohalogens. At this time, the lithium replenishment core is exposed to a high concentration of gaseous carbohalogen atmosphere. The solid and gas phases ensure sufficient contact between the two. After the gaseous carbohalogens undergo a dehalogenation reaction on the surface of the lithium replenishment core, a dense and uniform carbon coating layer can be generated in situ. This better isolates the lithium replenishment core from the air, preventing the lithium replenishment core from reacting and deteriorating with components such as moisture and carbon dioxide in the air. This improves the environmental tolerance of the positive electrode lithium replenishment agent, reduces the residual alkali content on the surface, and is beneficial for slurry coating. At the same time, the dense carbon coating layer significantly improves the conductivity of the positive electrode lithium replenishment agent, which is conducive to the full utilization of the lithium replenishment capacity.

[0062] The molecular weight of the coating additives added above should not be too large, otherwise it will be difficult to generate gaseous carbohalogen free radicals and halogen free radicals after thermal decomposition. Based on the above considerations, it is preferable that the molecular weight of the coating additives is <600, more preferably <300.

[0063] In one specific embodiment, the coating additive includes one or more of hexachlorobenzene, hexabromobenzene, chlorobenzene, bromobenzene, dichlorobenzene, and dibromobenzene. Among these, hexachlorobenzene has a higher residual carbon content and chlorine content than the other types of coating additives mentioned above, and can provide more highly active gaseous carbon-chlorine free radicals and chlorine free radicals. Therefore, hexachlorobenzene is more preferred as the coating additive.

[0064] Furthermore, the thermal decomposition temperature of the coating additive is <400℃, more preferably <250℃. It is understood that the sintering temperature is usually determined based on the carbonization temperature of the carbon source. Controlling the thermal decomposition temperature of the coating additive within the above range can meet the sintering temperature requirements of most carbon source materials, thus broadening the range of usable carbon sources.

[0065] In one specific implementation, the chemical composition of the lithium-supplemented core is Li. a M b O c Wherein, M includes one or more of Fe, Ni, Mn, Cu, Zn, Co, Cr, Zr, Sb, Ti, V, Mo, and Sn, 1 < a ≤ 8, 0 < b ≤ 1, and 0 < c < 7. For example, the lithium-filled core can specifically be Li5FeO4, Li2NiO2, Li6CoO4, Li2O2, etc., preferably Li5FeO4.

[0066] In a specific embodiment, the carbon source includes one or more of carbon black, graphene, carbon nanotubes, fullerenes, sucrose, glucose, asphalt, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, anthracene or aniline. The above carbon sources all have high conductivity, and can significantly improve the conductivity of the cathode lithium supplement agent after forming the carbon coating layer. It is worth mentioning that when the carbon source is selected from organic carbon sources (such as sucrose, glucose, asphalt, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, anthracene or aniline, etc.), the halogen radicals generated during the thermal decomposition of the coating additive can combine with the hydrogen atoms in the organic carbon source and escape in the form of hydrogen chloride, and promote the dehalogenation reaction of gaseous carbon halogen radicals on the surface of the lithium supplement core, thereby in-situ generating a dense and uniform carbon coating layer.

[0067] In a specific embodiment, the mass ratio of the lithium supplement core, carbon source and coating additive is 1:x:y, 0 < x < 10%, 0 < y < 10%. Within the above mass ratio range, it is beneficial to achieve a dense and uniform coating of the carbon coating layer on the surface of the lithium supplement core, and can also avoid the negative impact of too large mass ratio of the conductive carbon layer on the lithium supplement capacity of the cathode lithium supplement agent.

[0068] In a preferred embodiment, the D50 particle size of the cathode lithium supplement agent is 10 - 30 μm. When the D50 of the cathode lithium supplement agent is less than 10 μm, the particles are prone to agglomeration and the contact area with the electrolyte is too large, which easily leads to gas generation due to decomposition; when the D50 of the cathode lithium supplement agent is greater than 30 μm, the specific surface area of the material is too small, which is not conducive to the exertion of the lithium supplement capacity. Exemplarily, the D50 particle size of the cathode lithium supplement agent can be 10 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 20 μm, 21 μm, 23 μm, 25 μm, 27 μm, 29 μm, 30 μm or any range composed of any two of the above values. The D50 particle size of the cathode lithium supplement agent can be regulated by jointly using the particle size of the lithium supplement core and the thickness of the coating layer.

[0069] Furthermore, the thickness of the carbon coating layer is 100 - 200 nm. If the thickness of the carbon coating layer is too large, it will be unfavorable for the improvement of the battery energy density; if the thickness of the carbon coating layer is too small, it will be difficult to effectively protect the lithium supplement core, resulting in poor environmental tolerance. Controlling the thickness of the carbon coating layer within the above range can effectively protect the lithium supplement active material while reducing the adverse impact on the battery energy density. Exemplarily, the thickness of the carbon coating layer can be 100 nm, 120 nm, 140 nm, XXXXnm, 180 nm, 200 nm or any range composed of any two of the above values.

[0070] By controlling the above conditions, the positive electrode lithium supplement can have a lower porosity and a smaller specific surface area. Specifically, the specific surface area of the positive electrode lithium supplement is 0.3 to 0.8 m 2 / g.

[0071] The second aspect of the present application provides a preparation method of the positive electrode lithium supplement as described above, including the following steps:

[0072] Mix the lithium supplement core, carbon source and coating additive to obtain a mixture; sinter the mixture to obtain the positive electrode lithium supplement;

[0073] Among them, the coating additive includes a compound that can thermally decompose to generate gaseous carbon halogen radicals and halogen radicals, and the thermal decomposition temperature is not higher than the sintering treatment temperature.

[0074] The above method realizes in-situ dense coating of the carbon coating layer on the surface of the lithium supplement core through solid-phase mixing and sintering, and obtains a positive electrode lithium supplement with the peak intensities of the G peak, D peak and 1 peak satisfying 0.85 < IG / ID < 1.25, 9 < IG / I1 < 50, and 9 < ID / I1 < 50. This method does not require the addition of solvents, is more efficient and convenient, and is conducive to industrial production.

[0075] Furthermore, the temperature of the above sintering treatment is 80 to 1000 °C; the time is 3 to 15 hours, preferably 3 to 15 hours. When the carbon source is selected from inorganic materials such as carbon black, graphene, carbon nanotubes, and fullerenes, the sintering treatment can be carried out at a lower temperature, such as 80 to 300 °C; when the carbon source is selected from organic materials such as sucrose, glucose, asphalt, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethylcellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, anthracene or aniline, the sintering treatment needs to be carried out at a higher temperature to ensure the carbonization of the organic matter, such as 500 to 1000 °C.

[0076] To avoid interference from impurities and moisture in the air, the above sintering treatment is carried out in an inert atmosphere, and the inert gas can be selected from one or more of argon, nitrogen, helium, and neon.

[0077] In a specific embodiment, the lithium supplement core can be obtained by mixing a lithium source and an M source in a stoichiometric ratio and then sintering. The present application does not specifically limit the types of the lithium source, M source, and A source. Among them, the lithium source includes but is not limited to one or more of LiOH, Li2O, Li2O2, and Li2CO3; the M source includes but is not limited to one or more of oxides, hydroxides, carbonates, and nitrates of element M.

[0078] Furthermore, the sintering temperature during the lithium core preparation process is 80–1000℃, preferably 700–900℃; the sintering time is 3–15 hours, preferably 7–12 hours; and the heating rate is 3–10℃ / min, preferably 4–7℃ / min. The sintering process can be carried out in a muffle furnace. After sintering, to avoid structural changes due to rapid cooling, the sintered material can be allowed to cool naturally to room temperature with the furnace before being removed.

[0079] Currently, lithium-rich metal oxides, such as Li5FeO4, Li2NiO2, and Li2O2, are commonly used as lithium replenishers. These are added during the preparation of the positive electrode to compensate for the efficiency loss during the first charge and discharge of the negative electrode. Taking lithium iron phosphate (LFP) as the positive electrode active material and Li5FeO4 as the lithium replenisher as an example, the mechanism is as follows: During the first charge, the lithium replenisher releases a specific capacity >600 mAh / g, while the initial discharge capacity is typically 30 mAh / g to 40 mAh / g. This generates excess lithium ions to compensate for the lithium loss during the first efficiency of the graphite negative electrode and releases oxygen. The lithium supplement Li5FeO4 exhibits two charging plateaus during the initial charging process, approximately 3.5V–3.6V and 3.9V–4.0V respectively. At each plateau, Li5FeO4 undergoes a delithiation reaction, ultimately generating LiFeO2 and O2. Furthermore, the lithium supplement generally requires charging to a relatively high voltage (>4.0V) to achieve its maximum lithium supplementation effect; this voltage is higher than the typical voltage range of lithium iron phosphate (LFP) (approximately 2.0V–3.75V). Therefore, at high voltages, other gases or irreversible gas production occurs. The sources of this gas production include: firstly, the decomposition of the lithium supplement at high voltage, releasing oxygen; and secondly, the catalytic decomposition of the electrolyte by the delithiation products of the lithium supplement at high voltage.

[0080] In existing technologies, stable materials are used as additives or coatings for lithium replenishment to suppress electrolyte decomposition and gas production or eliminate oxygen, but the effect of reducing gas production is not significant.

[0081] Therefore, this application proposes a lithium replenishing agent, comprising: a core, the core including a lithium replenishing core; and a coating layer, the coating layer covering the core, the coating layer including an oxygen-deficient compound.

[0082] "Oxygen-deficient compounds" generally refer to compounds in which the oxygen content is lower than its stoichiometric ratio. For example, in some compound materials, due to the influence of manufacturing processes, heat treatment, or chemical environment, oxygen atoms in the crystal lattice may be partially missing, forming oxygen vacancies. Therefore, the valence state of the metal cations in these materials will be lower than the stable state, exhibiting a certain degree of reducing properties.

[0083] During the electrochemical reaction process, the lithium - supplement core, as a lithium - supplement material, will release a large amount of oxygen, resulting in excessive gas production during the formation stage. The residual reactive oxygen in the system after formation will continuously catalyze the decomposition of the electrolyte to produce gas during the high - temperature storage stage, and may even cause the battery valve to burst, leading to serious safety accidents. Therefore, the embodiments of the present application propose to add a reducing anoxic compound to the coating layer of the lithium - supplement agent. During the formation process of the lithium - supplement battery core, the released oxygen can be pumped away and discharged by a negative - pressure process. The residual reactive oxygen in the system will be consumed by the anoxic compound in the coating layer during the subsequent high - temperature storage stage. This is because the anoxic compound has a stronger reducing property than the electrolyte and can compete with the electrolyte and capture catalytic factors such as reactive oxygen in the system at a relatively high temperature, thereby reducing the catalytic decomposition of the electrolyte to produce gas.

[0084] In some embodiments of the present application, the anoxic compound includes at least one of anoxic metal compounds and anoxic non - metal compounds.

[0085] The anoxic compound selected in the embodiments of the present application has a stronger reducing property than the components of the electrolyte and can consume reactive catalytic factors such as reactive oxygen generated by the lithium - supplement agent during the formation stage and the high - temperature storage stage, thereby reducing the side reaction between the electrolyte and the lithium - supplement agent and further reducing the gas production.

[0086] "Anoxic metal compound" generally refers to a compound in which the oxygen content in the metal compound is lower than its stoichiometric ratio. For example, in some oxide materials, due to the influence of production processes, heat treatment, or chemical environments, some oxygen atoms in the crystal lattice may be partially missing, forming oxygen vacancies.

[0087] "Anoxic non - metal compound" generally refers to a situation where oxygen vacancies are formed in the crystal lattice of a non - metal compound due to the oxygen content being lower than its stoichiometric ratio.

[0088] In some embodiments of the present application, the anoxic metal compound includes at least one of Al2O 3-x 、MgO 1-y and TiO 2-z ; where 0 < x < 3, 0 < y < 1, 0 < z < 2; and / or, the anoxic non - metal compound includes SiO 2-a ; where 0 < a < 2.

[0089] The anoxic metal compound includes at least one of Al2O 3-x 、MgO 1-y and TiO 2-z ; where 0 < x < 3, 0 < y < 1, 0 < z < 2. In a specific example, Al2O 3-xAmong them, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.95, etc., or x is any integer or decimal between 0 and 3. In a specific example, MgO 1-y Among them, y can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, etc., or y is any integer or decimal between 0 and 1. In a specific example, TiO 2-z Among them, z can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.95, etc., or y is any integer or decimal between 0 and 2.

[0090] The oxygen-deficient metal oxides include Al2O 3-x and MgO 1-y and TiO 2-z at least one of them. These oxygen-deficient metal oxides have a lower cost; and because the relative molecular weights of these oxygen-deficient metal oxides are smaller, for the oxygen-deficient compounds of the same mass, there are more oxygen vacancies. Therefore, when the coating material of the lithium supplement agent is applied to the battery, it shows a good effect of consuming oxygen.

[0091] The oxygen-deficient non-metal compounds include SiO 2-a ; where 0 < a < 2. In a specific example, SiO 2-a Among them, a can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.95, etc., or a is any integer or decimal between 0 and 2.

[0092] In some embodiments of the present application, the oxygen-deficient compound is Al2O 3-x and MgO 1-y and TiO 2-z at least one of them.

[0093] In the embodiments of the present application, the oxygen-deficient metal oxides are Al2O 3-x and MgO 1-y and TiO 2-zAt least one of these oxygen-deficient metal oxides has a lower cost; and because the relative molecular mass of these oxygen-deficient metal oxides is smaller, for the same mass of oxygen-deficient compounds, there are more oxygen vacancies. Therefore, when the coating material of the lithium supplement agent is applied to the battery, the effect of consuming oxygen is better.

[0094] In some embodiments of the present application, the oxygen-deficient compound is Al2O 3-x , MgO 1-y and TiO 2-z At least one of them, and 0 < x < 1, 0 < y < 0.5, 0 < z < 1.

[0095] In the embodiments of the present application, at least one of the above three is selected as the oxygen-deficient compound, and the oxygen content is lower than its stoichiometric ratio. Therefore, the stability of these oxygen-deficient compounds is relatively high, the acquisition difficulty is low, and the total cost is relatively low.

[0096] In some embodiments of the present application, the oxygen-deficient oxide can be a commercial product, and / or the oxygen-deficient metal oxide can be prepared by a method including annealing treatment.

[0097] The oxygen-deficient metal oxide is prepared by mixing a metal oxide with a stable valence state and a reducing agent and then performing annealing treatment. The reducing agent includes a metal单质, a carbon material or other reducing agents.

[0098] In some embodiments of the present application, the preparation method of the oxygen-deficient metal oxide Al2O 3-x (0 < x < 3) includes:

[0099] Mix alumina and aluminum单质 according to the stoichiometric ratio, grind them, and then perform annealing treatment. The cooling regime is furnace cooling to obtain the oxygen-deficient metal oxide Al2O 3-x (0 < x < 3).

[0100] Among them, the control parameters include at least one of the following:

[0101] The annealing temperature is 300°C to 800°C; further, the annealing temperature is 300°C to 600°C;

[0102] The annealing time is 2h to 10h; further, the annealing time is 2h to 5h;

[0103] The heating rate is 2°C / min to 10°C / min; further, the heating rate is 3°C / min to 5°C / min;

[0104] In some embodiments of the present application, the preparation method of the oxygen-deficient metal oxide MgO 1-y (0 < y < 1) includes:

[0105] It should be noted that "单质" in the original text is likely a misspelling. It might be intended to be "element" or other appropriate terms. The above translation is based on the best understanding of the context.Mix magnesium oxide and magnesium单质 in a stoichiometric ratio, grind them, then perform annealing treatment. The cooling regime is furnace cooling to obtain oxygen-deficient metal oxide MgO 1-y (0 < y < 1).

[0106] Among them, the control parameters include at least one of the following:

[0107] The annealing temperature is 300°C to 800°C; further, the annealing temperature is 300°C to 600°C;

[0108] The annealing time is 2h to 10h; further, the annealing time is 2h to 5h;

[0109] The heating rate is 2°C / min to 10°C / min; further, the heating rate is 3°C / min to 5°C / min.

[0110] In some embodiments of the present application, the preparation method of oxygen-deficient metal oxide TiO 2-z (0 < z < 2) includes:

[0111] Mix titanium dioxide and titanium单质 in a stoichiometric ratio, grind them, then perform annealing treatment. The cooling regime is furnace cooling to obtain oxygen-deficient metal oxide TiO 2-z (0 < z < 2).

[0112] Among them, the control parameters include at least one of the following:

[0113] The annealing temperature is 300°C to 800°C; further, 300°C to 600°C;

[0114] The annealing time is 2h to 10h; further, the annealing time is 2h to 5h;

[0115] The heating rate is 2°C / min to 10°C / min; further, 3°C / min to 5°C / min.

[0116] It should be noted that the "单质" in the original text seems to be an incorrect expression. It might be a specific chemical term that needs to be accurately identified and corrected for a more accurate translation. Here it is tentatively translated as "单质" for now.In some embodiments of this application, based on a lithium-replenished core, the mass percentage m1 of the oxygen-deficient compound satisfies: 0 < m1 ≤ 10%. Specifically, the mass percentage m1 of the oxygen-deficient compound is 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4. 7%, 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7. 4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10%, etc.

[0117] In this embodiment, based on the lithium-replenishing core, the mass percentage m1 of the oxygen-deficient compound satisfies the above conditions, which is beneficial to increase the energy consumed by oxygen and improve the effect of reducing gas production; at the same time, it can avoid adding too much that would affect the lithium-replenishing effect of the core, so that the battery exhibits good battery capacity.

[0118] In some embodiments of this application, based on the lithium-replenished core, the mass percentage m1 of the oxygen-deficient compound satisfies: 0.1% < m1 ≤ 5%.

[0119] In this embodiment, based on the lithium-replenishing core, the mass percentage m1 of the oxygen-deficient compound satisfies the above conditions, which is beneficial to increase the energy consumed by oxygen and improve the effect of reducing gas production; at the same time, it does not affect the lithium replenishment effect of the core, and the battery exhibits good battery capacity.

[0120] In some embodiments of this application, the D50 of the oxygen-deficient compound is 20 nm to 200 nm; and / or, the D50 of the lithium-supplemented core is... 50 The range is from 1μm to 20μm.

[0121] In this embodiment, the D50 of the anoxic compound refers to the statistical average of the particle sizes of all particles in the anoxic compound particle population. Specifically, the D50 of the anoxic compound is 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, etc.

[0122] In this embodiment, the D50 of the oxygen-deficient compound satisfies the above conditions. Due to its smaller particle size, the compound is better dispersed during the process of forming the coated lithium replenishing agent in this embodiment, which is conducive to forming a coating layer with better density and improving the structural stability of the coating layer. Furthermore, the smaller particle size of the oxygen-deficient compound as the coating layer material results in a larger specific surface area, which is conducive to adsorbing active oxygen and improving the oxygen consumption effect.

[0123] Furthermore, the D50 of the anoxic compound is 20 nm to 50 nm. In specific examples, the D50 of the anoxic compound is 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, etc.

[0124] In this embodiment of the application, the D of the lithium-replenishing core 50 This is a particle size distribution parameter, representing the particle size at which the cumulative particle size distribution in the lithium replenishment core reaches 50%. That is, D 50 This means that in a set of particle size distributions, 50% of the particles have a diameter less than or equal to this value, while the other 50% have a diameter greater than or equal to this value. (D) 50 Also known as median diameter or median particle size, it is often used to approximate the average particle size of a sample. In a specific example, the Di of the lithium-filled core... 50 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 10μm, etc.

[0125] In this embodiment of the application, the D of the lithium-replenishing core 50If the above conditions are met, since the particle size is relatively small, the lithium-replenishing core is used as a lithium-replenishing material in the battery. The smaller the degree of particle cracking, the smaller the interface area exposed in the electrolyte, and the less gas may be generated, which is beneficial to improving battery performance.

[0126] Furthermore, the D of the lithium-ion core 50 The size ranges from 10μm to 14μm.

[0127] In some embodiments of this application, the lithium-filled core includes a binary lithium compound or a ternary lithium compound.

[0128] The lithium replenishing core provided in this application, as a lithium replenishing material, can be made of commonly used materials in the art for lithium replenishment. In specific examples, the lithium replenishing core includes binary lithium compounds or ternary lithium compounds.

[0129] Furthermore, the binary lithium compound includes at least one of lithium oxide (Li2O) and lithium peroxide (Li2O2).

[0130] Furthermore, the ternary lithium compound includes at least one of lithium hexacobalt oxide (Li6CoO4), lithium ferrite (Li5FeO4), lithium nickel oxide (Li2NiO2), and lithium silicate (Li2SiO3).

[0131] In some embodiments of this application, the lithium-filled core includes at least one of Li5FeO4, Li2NiO2, and Li2O2.

[0132] In this embodiment, at least one of Li5FeO4, Li2NiO2, and Li2O2 is selected as the lithium replenishment core, i.e., the lithium replenishment material. The voltage platform of these lithium replenishment cores matches that of commonly used cathode materials, with low cost and good environmental stability.

[0133] In some embodiments of this application, the lithium-filled core may be a commercial product and / or prepared using a solid-state method.

[0134] By mixing and grinding a lithium source or a lithium source with a non-lithium metal source (such as an iron source or a nickel source), and then conducting a high-temperature solid-state reaction with furnace cooling, the corresponding lithium-replenishing cores (such as Li5FeO4, Li2NiO2, Li2O2, etc.) can be synthesized.

[0135] Furthermore, the lithium source includes lithium hydroxide and / or lithium oxide; the non-lithium metal source includes the corresponding metal hydroxide and / or oxide.

[0136] Furthermore, the control parameters include at least one of the following:

[0137] The sintering temperature is 500℃~1000℃; further, the sintering temperature is 700℃~900℃;

[0138] The sintering time is 6h to 15h; further, the sintering time is 7h to 12h.

[0139] The heating rate is 3℃ / min to 10℃ / min; further, the heating rate is 4℃ / min to 7℃ / min.

[0140] In some embodiments of this application, the coating layer further includes a conductive material; the conductive material includes at least one of conductive carbon material and conductive non-carbon material.

[0141] The lithium-replenishing core in a lithium replenishing agent has a large band gap and poor intrinsic electronic conductivity. The conductive material in the lithium-replenishing core coating layer provides good conductivity, which can improve the electrical characteristics of the lithium-replenishing core, allowing it to fully exert its excellent lithium-replenishing properties in practical use.

[0142] In some embodiments of this application, the conductive carbon material includes organic conductive carbon material and / or inorganic conductive carbon material.

[0143] Furthermore, inorganic conductive carbon materials include at least one of carbon black, graphene, carbon nanotubes, fullerenes, and amorphous carbon. The amorphous carbon is obtained by carbonizing precursor materials such as glucose, pitch, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, polyaniline, anthracene, and aniline.

[0144] Furthermore, the organic conductive carbon material includes at least one of carbon materials such as polypyrrole, polyaniline, polyethylene glycol, anthracene, and aniline.

[0145] In some embodiments of this application, the conductive material is at least one of carbon black, graphene, carbon nanotubes, and fullerene.

[0146] In some embodiments of this application, the conductive non-carbon material includes at least one of silver and copper.

[0147] In some embodiments of this application, the water contact angle of the conductive material is 90°≤θ≤160°. When the water contact angle of the conductive material is within this range, the conductive material exhibits hydrophobicity, which can improve the environmental stability of the lithium supplement. The conductive carbon black has a water contact angle of 100°≤θ≤150°, exhibiting excellent hydrophobicity.

[0148] Because the lithium replenishment core is easily degraded when exposed to water and carbon dioxide in the environment, affecting the lithium replenishment effect, this embodiment incorporates a hydrophobic conductive material in the coating layer covering the core surface. This effectively isolates the lithium replenishment core from the environment, preventing reactions between the core and environmental substances such as moisture and carbon dioxide, thus protecting the core. In a specific example, the conductive material is carbon black.

[0149] In some embodiments of this application, based on the lithium-filled core, the mass percentage m2 of the conductive material satisfies: 0 < m2 ≤ 10%. Specifically, based on the lithium-filled core, the mass percentage m2 of the conductive material is 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1... 0.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6% %, 4.7%, 4.8%, 4.9%, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10%, etc.

[0150] In this embodiment, based on the lithium replenishment core, the mass percentage m2 of the conductive material satisfies the above conditions, which is beneficial to increase the conductivity of the lithium replenishment agent.

[0151] In some embodiments of this application, based on the lithium-filled core, the mass percentage m2 of the conductive material satisfies: 0 < m2 ≤ 5%.

[0152] In this embodiment, based on the lithium replenishment core, the mass percentage m2 of the conductive material satisfies the above conditions, which is beneficial to increase the conductivity of the lithium replenishment agent, obtain a better coating effect, and has good hydrophobicity.

[0153] This application provides a method for preparing a lithium supplement, comprising:

[0154] A mixture is obtained by mixing a lithium-replenishing core and an oxygen-deficient compound, and the mixture is then heat-treated to obtain a lithium-replenishing agent.

[0155] The raw materials described in the examples can be directly "lithium-replenishing core" and "oxygen-deficient compound"; or they can refer to the raw materials for preparing "lithium-replenishing core" and "oxygen-deficient compound".

[0156] The lithium replenishing agent prepared according to the embodiments of this application can be obtained by mixing, which is simple to operate and has low cost. The lithium replenishing agent prepared according to the embodiments of this application contains oxygen-deficient compounds in the coating layer, which have stronger reducing properties than electrolyte components. It can consume active catalytic factors such as reactive oxygen species generated by the lithium replenishing agent in the formation stage and high-temperature storage stage, thereby reducing side reactions between the electrolyte and the lithium replenishing agent, and thus reducing gas production.

[0157] In some embodiments of this application, the step of mixing the lithium core and the oxygen-deficient compound to obtain a mixture further includes adding a conductive material.

[0158] A mixture is obtained by mixing a lithium-replenishing core, an oxygen-deficient compound, and a conductive material. The mixture is then heat-treated to obtain a lithium-replenishing agent.

[0159] The lithium-replenishing core in lithium replenishing agents has a large band gap and poor intrinsic electronic conductivity. By adding conductive materials, both the conductive materials and oxygen-deficient compounds are used to form a coating layer, which provides good conductivity and improves the electrical characteristics of the lithium-replenishing core, allowing it to fully exert its excellent lithium-replenishing properties in practical applications.

[0160] Conductive materials include at least one of conductive carbon materials and conductive non-carbon materials.

[0161] In some embodiments of this application, the step of mixing the raw materials of the lithium-replenishing core and the oxygen-deficient compound is performed by a physical-mechanical mixing method; or, the step of mixing the lithium-replenishing core, the oxygen-deficient compound, and the conductive material to obtain a mixture is performed by a physical-mechanical mixing method.

[0162] In this embodiment of the application, the raw materials are mixed by means of physical-mechanical mixing, so that the lithium core and the oxygen-deficient compound are in full contact, and a coating layer containing the oxygen-deficient compound is formed on the surface of the lithium core.

[0163] Furthermore, during the physical-mechanical mixing process, the mixing time is controlled to be 2 to 8 hours.

[0164] In some embodiments of this application, raw materials including lithium-replenishing cores and oxygen-deficient compounds are mixed and processed, and heat treatment is further controlled; the heat treatment control parameters include: heat treatment temperature of 20°C to 200°C, and / or heat treatment time of 1h to 6h.

[0165] In this embodiment, the lithium replenishing agent is prepared by mixing the raw materials and then heat-treating them. Heat treatment promotes bonding between the oxygen-deficient compounds and the lithium replenishing core at the interface, increasing the bonding strength between the coating layer and the core. This improves the structural stability of the lithium replenishing agent and protects the lithium replenishing core from deterioration due to contact with water and carbon dioxide in the environment, thereby improving battery performance. This is because, under heat treatment conditions,

[0166] Oxygen-deficient compounds have lattice defects that facilitate bonding with transition metals in the lithium-supplementing core, which is beneficial for improving the bonding strength. The lattice oxygen in the lithium-supplementing core occupies the oxidation vacancies in the oxygen-deficient compound, which can also improve the bonding strength.

[0167] In some embodiments of this application, the oxygen-deficient compound is prepared by the following method:

[0168] A metal oxide or non-metal oxide is mixed with a reducing agent and then annealed to obtain an oxygen-deficient compound; wherein the annealing parameters include at least one of the following:

[0169] (a) The annealing temperature is 500℃~1000℃;

[0170] (b) Annealing time is 6h to 15h;

[0171] (c) Annealing is carried out under an inert atmosphere.

[0172] Oxygen-deficient metal oxides are prepared by mixing stable valence metal oxides with elemental metals and then annealing the mixture.

[0173] The aforementioned "reducing agent," when mixed with metal oxides to prepare oxygen-deficient metal compounds, can reduce some metals from a high valence state to a low valence state; and when mixed with nonmetal oxides to prepare oxygen-deficient nonmetal compounds, it can reduce some nonmetals from a high valence state to a low valence state. Commonly used reducing agents in this field can be employed.

[0174] Furthermore, in the step of preparing the oxygen-deficient metal compound, the reducing agent used includes the corresponding elemental metal. That is, the metal oxide is mixed with its corresponding elemental metal, and then annealed to obtain the oxygen-deficient metal compound.

[0175] Furthermore, in the step of preparing the oxygen-deficient nonmetallic compound, the reducing agent used includes the corresponding nonmetallic element. That is, the nonmetallic oxide is mixed with its corresponding nonmetallic element, and then annealed to obtain the oxygen-deficient nonmetallic compound.

[0176] In some embodiments of the present application, the preparation method of the oxygen-deficient metal oxide Al2O 3-x (0 < x < 3) includes:

[0177] Mix alumina and aluminum单质 in a stoichiometric ratio, grind them, then perform annealing treatment, and the cooling regime is furnace cooling to obtain the oxygen-deficient metal oxide Al2O 3-x (0 < x < 3).

[0178] Among them, the control parameters include at least one of the following:

[0179] The annealing temperature is 300°C to 800°C; further, the annealing temperature is 300°C to 600°C;

[0180] The annealing time is 2h to 10h; further, the annealing time is 2h to 5h;

[0181] The heating rate is 2°C / min to 10°C / min; further, the heating rate is 3°C / min to 5°C / min;

[0182] In some embodiments of the present application, the preparation method of the oxygen-deficient metal oxide MgO 1-y (0 < y < 1) includes:

[0183] Mix magnesium oxide and magnesium单质 in a stoichiometric ratio, grind them, then perform annealing treatment, and the cooling regime is furnace cooling to obtain the oxygen-deficient metal oxide MgO 1-y (0 < y < 1).

[0184] Among them, the control parameters include at least one of the following:

[0185] The annealing temperature is 300°C to 800°C; further, the annealing temperature is 300°C to 600°C;

[0186] The annealing time is 2h to / 10h; further, the annealing time is 2h to 5h;

[0187] The heating rate is 2°C / min to 10°C / min; further, the heating rate is 3°C / min to 5°C / min.

[0188] In some embodiments of the present application, the preparation method of the oxygen-deficient metal oxide TiO 2-z (0 < z < 2) includes:

[0189] Mix titanium dioxide and titanium单质 in a stoichiometric ratio, grind them, then perform annealing treatment, and the cooling regime is furnace cooling to obtain the oxygen-deficient metal oxide TiO 2-z (0 < z < 2). It should be noted that the "单质" in the original text is not a standard chemical term. I translated it according to the context as "element", but it might need to be adjusted according to the accurate chemical concept.

[0190] The control parameters include at least one of the following:

[0191] The annealing temperature is 300℃~800℃; further, 300℃~600℃;

[0192] The annealing time is 2 hours to 10 hours; further, the annealing time is 2 hours to 5 hours.

[0193] The heating rate is 2℃ / min to 10℃ / min; further, 3℃ / min to 5℃ / min.

[0194] 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 positive lithium supplement agent provided in the first aspect of this application.

[0195] The positive electrode sheet of this application, because it includes the aforementioned positive electrode lithium replenishing agent, exhibits excellent lithium replenishment effect and environmental stability when applied to batteries. It also demonstrates good lithium replenishment performance and helps reduce gas production.

[0196] The positive current collector of this application may be selected from those conventionally used in the art. Further, the positive current collector may include a metal foil or a composite positive current collector. For example, the metal foil may be aluminum foil. The composite positive current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. For example, the composite negative current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0197] In addition to the positive electrode lithium replenishing agent, the positive electrode active material layer of this application also includes components such as positive electrode active material, conductive agent and binder.

[0198] The positive electrode active material can be any positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2) or its modified compounds. Examples of lithium phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, or lithium manganese iron phosphate and carbon composites.

[0199] In some embodiments of this application, the positive electrode active material includes LiFePO4 and LiNi. c Co d Mn 1-c-d O2, wherein at least one of 0.3≤c<1 and 0≤d≤0.5.

[0200] Conductive agents include, but are not limited to, one or more of the following: superconducting carbon, conductive carbon black, Super-C, acetylene black, Ketjen black, carbon dots, carbon nanotubes, and graphene carbon nanofibers.

[0201] The adhesive includes, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC-Na), polyvinylpyrrolidone, polytetrafluoroethylene, styrene-butadiene rubber (SBR), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0202] The more positive electrode lithium supplementer in the positive electrode active material layer, the better the lithium supplementation effect. However, excessive positive electrode lithium supplementer will inevitably lead to a decrease in the content of positive electrode active material, which is not conducive 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 80%, and the mass content of positive electrode lithium supplementer should be less than 10%.

[0203] In one specific embodiment, the positive electrode sheet can be prepared by the following method: the positive active material, the positive lithium supplement, the conductive agent and the 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 current collector. After drying, slitting and rolling, the positive electrode sheet can be obtained.

[0204] This application provides a battery including the aforementioned positive electrode sheet. Because the battery includes the aforementioned positive electrode sheet with a positive electrode lithium supplement, it exhibits higher initial coulombic efficiency and superior cycle performance during use.

[0205] In addition to the aforementioned positive electrode, the battery of this application also includes a negative electrode, an electrolyte, and a separator.

[0206] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. The negative current collector can be selected from negative current collectors conventionally used in the art, such as copper foil. The negative active material layer can also refer to conventional compositions in the art; for example, the negative active material layer includes a negative active material, a conductive agent, and a binder. The negative active material can be selected from negative active materials conventionally used in the art, including, but not limited to, one or more of natural graphite, artificial graphite, silicon-carbon materials, silicon-oxygen 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.

[0207] 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. This application does not specifically limit the type of separator, which can be a porous separator 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 non-woven fabric.

[0208] An electrolyte is a medium existing between the positive and negative electrode plates 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.

[0209] In some embodiments of this application, the battery may include an outer packaging. This outer packaging is used to encapsulate the positive electrode, the negative electrode, and the electrolyte.

[0210] In some embodiments of this application, the outer packaging may include a shell and a cover. The shell may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The shell has an opening communicating with the receiving cavity, and the cover plate can be placed over the opening to close the receiving cavity.

[0211] In some embodiments of this application, the outer packaging of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0212] The outer packaging of the battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0213] In one specific embodiment, the battery of this application can be prepared by the following method: after stacking the positive electrode, separator and negative electrode in sequence, the battery cell is obtained by stacking or winding process, and then the battery of this application can be obtained by baking, liquid injection, formation and packaging processes.

[0214] 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 cars, electric toys, energy storage devices, etc.

[0215] It should be noted that the features and advantages described above for the positive electrode lithium replenisher of the first aspect of this application also apply to the battery of the fourth aspect and the electrical equipment of the fifth aspect of this application, and will not be repeated here.

[0216] 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.

[0217] In the following examples and comparative examples, the carbon coating thickness was tested using the CP-SEM method. First, the sample was cross-sectionally processed by CP, and then its microstructure was observed in SEM to determine the coating thickness.

[0218] D50 particle size testing method: The particle size distribution is detected by a Malvern laser particle size analyzer, and the particle size value corresponding to the cumulative distribution percentage reaching 50% is taken.

[0219] In the following embodiments, the particle size of the positive electrode lithium replenisher D50 is controlled by selecting lithium replenishment core materials with different particle sizes and controlling the thickness of the conductive carbon layer.

[0220] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0221] Example 1

[0222] This embodiment provides a positive electrode lithium replenishing agent, comprising a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 100 nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20 μm. Its preparation method includes the following steps:

[0223] 1) Lithium hydroxide and iron oxide were mixed and ground at a molar ratio of 5:0.5 to obtain a first mixture; the first mixture was placed in a muffle furnace and heated to 700°C at a heating rate of 6°C / min under a nitrogen atmosphere, held at the temperature for 12 hours and then cooled to room temperature with the furnace to obtain Li5FeO4 powder.

[0224] 2) Mix Li5FeO4 powder, coating additive C6Cl6, and carbon black in a mass ratio of 100:0.2:2 to obtain a second mixture; under a nitrogen atmosphere, heat the second mixture to 200℃ at a heating rate of 5℃ / min, hold for 3h, and then cool naturally to room temperature to obtain the positive electrode lithium replenishing agent.

[0225] Example 2

[0226] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that in Example 1, except that in step 2), the mixing ratio of Li5FeO4 powder, coating additive C6Cl6, and carbon black is replaced with 100:0.5:2.

[0227] Example 3

[0228] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that in Example 1, except that in step 2), the mixing ratio of Li5FeO4 powder, coating additive C6Cl6, and carbon black is replaced with 100:0.8:2.

[0229] Example 4

[0230] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, the thickness of the carbon coating layer is 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that in step 2), the coating additive is replaced with C6Br6.

[0231] Example 5

[0232] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, the thickness of the carbon coating layer is 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that in step 2), the heat preservation time is replaced with 6 hours.

[0233] Example 6

[0234] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 150nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that in Example 1, except that in step 2), the mixing ratio of Li5FeO4 powder, coating additive C6Cl6, and carbon black is replaced with 100:0.2:4.

[0235] Example 7

[0236] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 180nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that in Example 1, except that in step 2), the mixing ratio of Li5FeO4 powder, coating additive C6Cl6, and carbon black is replaced with 100:0.2:6.

[0237] Example 8

[0238] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, the thickness of the carbon coating layer is 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that in step 2), carbon black is replaced with sucrose, and the sintering heat treatment temperature is replaced with 900℃.

[0239] Example 9

[0240] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, the thickness of the carbon coating layer is 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that in step 2), carbon black is replaced with polyethylene glycol, and the sintering temperature is replaced with 900℃.

[0241] Example 10

[0242] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, and the thickness of the carbon coating layer is 100nm. Its preparation method is basically the same as that in Example 1, except that the D50 particle size of the positive electrode lithium replenishing agent is 10μm.

[0243] Example 11

[0244] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li5FeO4, and the thickness of the carbon coating layer is 100nm. Its preparation method is basically the same as that in Example 1, except that the D50 particle size of the positive electrode lithium replenishing agent is 30μm.

[0245] Example 12

[0246] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The composition of the lithium replenishing core is Li2NiO2, the thickness of the carbon coating layer is 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that in step 1), the first mixture is replaced with a sample obtained by mixing and grinding lithium hydroxide and nickel oxide in a molar ratio of 2:1.

[0247] Example 13

[0248] This embodiment provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer covering the surface of the lithium replenishing core. The preparation method includes the following steps:

[0249] Step 1: Preparation of lithium-filled cores:

[0250] The lithium source and the iron source were mixed and ground in a stoichiometric ratio (molar ratio 10:1) to obtain a mixture; wherein the lithium source and the iron source were lithium hydroxide and iron oxide, respectively.

[0251] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 700℃, and an annealing time of 12h. After furnace cooling to room temperature, it was then ground at a grinding power of 50kW. This yielded a lithium-core Li5FeO4 powder sample with a D50 of 12μm.

[0252] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0253] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 7:1) at a grinding power of 20 kW to obtain a mixture.

[0254] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5 hours in an inert atmosphere. After furnace cooling to room temperature, it was ground at a grinding power of 80 kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina (Al₂O₃). 2.8 Powder sample, D50 is 50nm.

[0255] Step 3: Prepare conductive carbon material:

[0256] Carbon black is used as the conductive carbon material.

[0257] Step 4: Preparation of the positive electrode lithium supplement:

[0258] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and Al2O4 were mixed together. 2.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture is heat-treated at 150°C for 5 hours to obtain the positive electrode lithium replenishing agent, which is named "Example 13". The order of the first, second and third steps above can be interchanged.

[0259] Example 14

[0260] The difference between this embodiment and Embodiment 13 is that in the fourth step, Li5FeO4 and Al2O4 are added. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 97:2:1 and then heat-treated at 150°C for 5 hours to obtain a lithium replenishing agent, which was named "Example 14".

[0261] Example 15

[0262] The difference between this embodiment and embodiment 13 is as follows:

[0263] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0264] Magnesium oxide and elemental magnesium were mixed and ground in a stoichiometric ratio (molar ratio 4:1) at a grinding power of 20 kW to obtain a mixture.

[0265] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 88kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina MgO. 0.8 Powder sample, D50 is 50nm.

[0266] Step 3: Prepare conductive carbon material:

[0267] Carbon black is used as the conductive carbon material.

[0268] Step 4: Preparation of lithium supplement:

[0269] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and MgO were mixed together. 0.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture was heat-treated at 150°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 15".

[0270] Example 16

[0271] The difference between this embodiment and embodiment 15 is as follows:

[0272] The fourth step involves mixing Li5FeO4 and MgO. 0.8 Conductive carbon materials were uniformly mixed at a mass ratio of 97:2:1 and then heat-treated at 150°C for 5 hours to obtain a lithium replenishing agent, which was named "Example 16".

[0273] Example 17

[0274] The difference between this embodiment and embodiment 13 is as follows:

[0275] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0276] Titanium oxide and elemental titanium were mixed and ground in a stoichiometric ratio (molar ratio 9:1) at a grinding power of 15 kW to obtain a mixture.

[0277] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5 hours. After furnace cooling to room temperature, it was then ground at a grinding power of 90 kW. This yielded an oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina TiO₂. 1.8 Powder sample, D50 is 50nm.

[0278] Step 3: Prepare conductive carbon material:

[0279] Carbon black is used as the conductive carbon material.

[0280] Step 4: Preparation of the positive electrode lithium supplement:

[0281] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and TiO2 were mixed together. 1.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture was heat-treated at 150°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 17".

[0282] Example 18

[0283] The difference between this embodiment and embodiment 15 is as follows:

[0284] The fourth step is to combine Li5FeO4 and TiO2. 1.8 Conductive carbon materials were uniformly mixed at room temperature (20°C) in a mass ratio of 97:2:1, and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 18".

[0285] Example 19

[0286] The difference between this embodiment and embodiment 13 is as follows:

[0287] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0288] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 2.5:1) at a grinding power of 20 kW to obtain a mixture.

[0289] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 80kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina Al2O3. 2.5 Powder sample, D50 is 50nm.

[0290] The lithium supplement was obtained and named "Example 19".

[0291] Example 20

[0292] The difference between this embodiment and embodiment 13 is as follows:

[0293] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0294] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 1.64:1) at a grinding power of 20 kW to obtain a mixture.

[0295] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 80kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina Al2O3. 2.3 Powder sample, D50 is 50nm.

[0296] The positive electrode lithium replenishing agent was obtained and named "Example 20".

[0297] Example 21

[0298] The difference between this embodiment and embodiment 13 is as follows:

[0299] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 98.9:0.1:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 21".

[0300] Example 22

[0301] The difference between this embodiment and embodiment 13 is as follows:

[0302] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 97.5:1.5:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 22".

[0303] Example 23

[0304] The difference between this embodiment and embodiment 13 is as follows:

[0305] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 96:3:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 23".

[0306] Example 24

[0307] The difference between this embodiment and embodiment 13 is as follows:

[0308] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 94:5:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 24".

[0309] Example 25

[0310] The difference between this embodiment and embodiment 13 is as follows:

[0311] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed at a mass ratio of 89:10:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 25".

[0312] Example 26

[0313] The difference between this embodiment and embodiment 13 is as follows:

[0314] The fourth step involves mixing Li5FeO4 and Al2O3. 2.8 Conductive carbon materials were uniformly mixed in a mass ratio of 88.5:10.5:1 and then heat-treated at 150°C for 5 hours to obtain a positive electrode lithium replenishing agent, which was named "Example 26".

[0315] Example 27

[0316] The difference between this embodiment and embodiment 13 is as follows:

[0317] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0318] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 7:1) at a grinding power of 18 kW to obtain a mixture.

[0319] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 150kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina Al2O3. 2.8 Powder sample, D50 is 20nm.

[0320] The positive electrode lithium replenishing agent was obtained and named "Example 27".

[0321] Example 28

[0322] The difference between this embodiment and embodiment 13 is as follows:

[0323] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0324] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 7:1) at a grinding power of 15 kW to obtain a mixture.

[0325] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 60kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina Al2O3. 2.8 Powder sample, D50 is 150nm.

[0326] The positive electrode lithium replenishing agent was obtained and named "Example 28".

[0327] Example 29

[0328] The difference between this embodiment and embodiment 13 is as follows:

[0329] Step 2: Preparation of oxygen-deficient non-lithium metal oxides:

[0330] Alumina and elemental aluminum were mixed and ground in a stoichiometric ratio (molar ratio 7:1) at a grinding power of 15 kW to obtain a mixture.

[0331] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 50kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina Al2O3. 2.8 Powder sample, D50 is 200nm.

[0332] The positive electrode lithium replenishing agent was obtained and named "Example 29".

[0333] Example 30

[0334] The difference between this embodiment and embodiment 13 is as follows:

[0335] Step 2: Preparation of oxygen-deficient non-lithium non-metallic oxides:

[0336] Silica and elemental silicon were mixed and ground in a stoichiometric ratio (molar ratio 9:1) at a grinding power of 10 kW to obtain a mixture.

[0337] The resulting mixture was subjected to high-temperature annealing at a heating rate of 6℃ / min, an annealing temperature of 500℃, and an annealing time of 5h. After furnace cooling to room temperature, it was ground at a grinding power of 40kW to obtain oxygen-deficient non-lithium metal oxide, namely oxygen-deficient alumina SiO. 1.8 Powder sample, D50 is 50nm.

[0338] The positive electrode lithium replenishing agent was obtained and named "Example 30".

[0339] Example 31

[0340] The difference between this embodiment and embodiment 13 is as follows:

[0341] The third step is to prepare conductive materials: polypyrrole is used as the conductive material.

[0342] The positive electrode lithium replenishing agent was obtained and named "Example 31".

[0343] Example 32

[0344] The difference between this embodiment and embodiment 13 is as follows:

[0345] The first step is to use Li2O2 as the positive electrode lithium supplement, with a D50 of 50nm.

[0346] The positive electrode lithium replenishing agent was obtained and named "Example 32".

[0347] Example 33

[0348] The preparation methods in this embodiment are entirely the same as those in Example 13, except that: the positive electrode lithium replenishing agent provided in Example 1 is used in lithium iron phosphate batteries (i.e., the positive electrode active material is lithium iron phosphate), while the positive electrode lithium replenishing agent prepared in this embodiment is used in 811 series batteries (i.e., the positive electrode active material is LiNi). 0.8 Co 0.1 Mn 0.1 O2).

[0349] Example 34

[0350] The difference between this embodiment and embodiment 13 is as follows:

[0351] The third step involves mixing Li5FeO4 and Al2O4 without using conductive materials. 2.8 The modified lithium supplement material was obtained by uniformly mixing the materials at a mass ratio of 99:1 for 5 hours, and named "Example 34".

[0352] Example 35

[0353] The difference between this embodiment and embodiment 13 is as follows:

[0354] Step 4: Preparation of the positive electrode lithium supplement:

[0355] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and Al2O4 were mixed together. 2.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture was heat-treated at 40°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 35".

[0356] Example 36

[0357] The difference between this embodiment and embodiment 13 is as follows:

[0358] Step 4: Preparation of the positive electrode lithium supplement:

[0359] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and Al2O4 were mixed together. 2.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture was heat-treated at 100°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 36".

[0360] Example 37

[0361] The difference between this embodiment and embodiment 13 is as follows:

[0362] Step 4: Preparation of the positive electrode lithium supplement:

[0363] A physical-mechanical mixing method was adopted: the above-obtained Li5FeO4 and Al2O4 were mixed together. 2.8 After being uniformly mixed with conductive carbon material at a mass ratio of 98:1:1, the mixture was heat-treated at 200°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 37".

[0364] Example 38

[0365] The difference between Example 38 and Example 13 is as follows:

[0366] The second step is not performed, that is, the oxygen-deficient alumina Al2O is not produced. 2.8 The resulting Li5FeO4 and conductive carbon material were uniformly mixed at a mass ratio of 98:2 and then heat-treated at 150°C for 5 hours to obtain the positive electrode lithium replenishing agent, which was named "Example 38".

[0367] Example 39

[0368] The same method as in Example 13 was used, except that aluminum oxide (Al2O3) was used instead of the oxygen-deficient compound (Al2O3). 2.8 ), with all other conditions remaining unchanged.

[0369] Example 40

[0370] The same method as in Example 32 is used, except that:

[0371] The second step is not performed, that is, the oxygen-deficient alumina Al2O is not produced. 2.8 The coating process involves uniformly mixing Li2O2 and conductive carbon material at a mass ratio of 98:2, followed by heat treatment at 150°C for 5 hours to obtain the positive electrode lithium replenishing agent, which is named "Example 40".

[0372] Example 41

[0373] The same method as in Example 33 was used, except that aluminum oxide (Al2O3) was used instead of the oxygen-deficient compound (Al2O3). 2.8 ), with all other conditions remaining unchanged.

[0374] Comparative Example 1

[0375] This comparative example provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The lithium replenishing core is composed of Li5FeO4, the carbon coating layer has a thickness of 100nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20μm. Its preparation method is basically the same as that of Example 1, except that: in step 2), no coating additive C6Cl6 is added, and Li5FeO4 powder and carbon black are mixed in a mass ratio of 100:2 to obtain a second mixture.

[0376] Comparative Example 2

[0377] This comparative example provides a positive electrode lithium replenishing agent, including a lithium replenishing core and a carbon coating layer on the surface of the lithium replenishing core. The lithium replenishing core is composed of Li2NiO2, the carbon coating layer has a thickness of 100 nm, and the D50 particle size of the positive electrode lithium replenishing agent is 20 μm. Its preparation method is basically the same as that of Example 12, except that: in step 2), no coating additive C6Cl6 is added, and a second mixture is obtained by mixing Li2NiO2 powder and carbon black at a mass ratio of 100:2.

[0378] The following performance tests were conducted on the positive electrode lithium replenishing agents of Examples 1-12 and Comparative Examples 1-2:

[0379] 1. Resistivity

[0380] Test method: The resistivity of the positive electrode lithium supplement was tested at 25℃ using a powder resistivity meter. The test results are shown in Table 1.

[0381] 2. Specific surface area

[0382] Test method: Approximately 1 mg of sample was selected for testing. A multi-point BET detection method was used, with N2 as the adsorbed gas and an adsorption temperature of -195℃. The test results are shown in Table 1.

[0383] 4. Moisture absorption rate

[0384] Test method: The moisture absorption rate of the positive electrode lithium replenishment agent was tested in a constant temperature and humidity chamber at 25℃ and 40% humidity, 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.

[0385] 5. Residual alkali content

[0386] Test method: Use methanol as a solvent to dissolve the residual alkali on the surface of the positive electrode lithium supplement, obtain the test solution, conduct potentiometric titration testing on the test solution, use a 0.01M HCl standard solution for titration to obtain the titration curve, and respectively test and obtain the contents of LiOH and Li2CO3 in the positive electrode lithium supplement. The test results are shown in Table 1.

[0387] 6. Raman spectroscopy test

[0388] Test method: The test laser wavelength is 532 nm, and the acquisition wavenumber range is 100 - 5000 cm -1 , obtain the Raman spectrum, determine the G peak, D peak, and 1 peak according to the displacement values of the Raman spectrum, analyze the spectrum, obtain their peak intensity values, calculate IG / ID, IG / I1, and ID / I1, and the results are listed in Table 1.

[0389] Figure 3 is the Raman spectrum of the positive electrode lithium supplement of Example 11. As shown in Figure 3, this positive electrode lithium supplement includes a G peak with a displacement range of 1,560 - 1,580 cm -1 , a D peak with a displacement range of 1,350 - 1,370 cm -1 , and a 1 peak with a displacement range of 655 - 675 cm -1 . Calculate that IG / ID is 0.97, IG / I1 is 17, and ID / I1 is 17.

[0390] 7. SEM test

[0391] Test method: Conduct scanning electron microscopy (SEM) testing on the positive electrode lithium supplements of Example 1 and Comparative Example 1. Figure 4 is the SEM image of the positive electrode lithium supplement of Example 1, and Figure 5 is the SEM image of the positive electrode lithium supplement of Comparative Example 1. By comparing Figure 1 and Figure 2, it can be seen that compared with the positive electrode lithium supplement of Comparative Example 1, the carbon coating layer on the surface of the positive electrode lithium supplement of Example 1 is denser.

[0392] Table 1

[0393] The following conclusions can be analyzed from Table 1:

[0394] 1) By comparing Examples 1 - 12 with Comparative Examples 1 - 2, when the peak intensity IG of the G peak, the peak intensity ID of the D peak, and the peak intensity I1 of the 1 peak in the Raman spectrum satisfy 0.85 < IG / ID < 1.25, 9 < IG / I1 < 50, and 9 < ID / I1 < 50, the denseness of the coating layer is good, the resistivity of the positive electrode lithium supplement is significantly lower, and the specific surface area, moisture absorption rate, and residual alkali content are also at relatively low levels.

[0395] 2) The comparison of Examples 1 to 3 shows that as the content of coating additives increases, the proportion of the G peak intensity of the positive electrode lithium replenishment agent gradually increases, indicating that the carbon coating layer of the positive electrode lithium replenishment agent has a higher degree of graphitization, enhanced conductivity, gradually decreased resistivity, gradually decreased specific surface area, and the moisture absorption rate and residual alkali level of the material also decrease accordingly.

[0396] 3) The comparison between Examples 1 and 4 shows that, compared with C6Br6, C6Cl6 as a coating additive forms a carbon coating layer with better coating effect and lower surface residual alkali content.

[0397] 4) By comparing Examples 1 and 5, it can be seen that the longer the sintering and heat preservation time of the carbon coating layer, the more thorough the decomposition time of hexachlorobenzene, the better the coating effect, the larger the proportion of G peak intensity, and the smaller the specific surface area, resistivity, moisture absorption rate, and residual alkali content.

[0398] 4) By comparing Examples 1, 6 and 7, it can be seen that as the thickness of the carbon coating layer increases, the proportion of the G peak intensity of the positive electrode lithium supplement gradually increases, indicating that the carbon coating layer of the positive electrode lithium supplement has a higher degree of graphitization, enhanced conductivity, gradually decreased resistivity, gradually decreased specific surface area, and the moisture absorption rate and residual alkali level of the material also decrease accordingly.

[0399] 5) Based on the comparison of Examples 1, 8 and 9, it can be seen that different types of carbon sources have little effect on the coating effect. Different types of organic and inorganic carbon sources, such as carbon black, sucrose and polyethylene glycol, can enable the positive electrode lithium supplement to have low resistivity, low specific surface area, low dilution rate and low residual alkali level.

[0400] 6) According to the comparison of Examples 1, 10 and 11, it can be seen that as the particle size of the positive electrode lithium replenishing agent D50 increases, the specific surface area decreases, the contact area with air decreases, and it is not easy to absorb moisture and deteriorate. The resistivity, moisture absorption rate and residual alkali level show a gradual decreasing trend, showing a better coating effect.

[0401] The following performance tests were conducted on the positive electrode lithium replenishing agents of Examples 13-41 above:

[0402] The D50 of the positive electrode lithium replenishment material is tested using a Malvern laser particle size analyzer.

[0403] The D50 of anaerobic compounds was determined using a Malvern laser particle size analyzer.

[0404] Methods for detecting the mass percentage of anoxic compounds: control during feeding by weighing, and use ICP testing at the finished product level.

[0405] Characterization method for the oxygen-deficient state of compounds: XPS test, which characterizes the valence state of metal elements and oxygen.

[0406] Methods for detecting the mass percentage of conductive materials: Weighing control is used during material feeding, and elemental analysis or thermogravimetric analysis is used for the finished product.

[0407] The test parameters are shown in Table 2.

[0408] Table 2

[0409] Preparation example:

[0410] Preparation of the positive electrode sheet: A positive electrode slurry was prepared by combining the binder PVDF (polyvinylidene fluoride), the conductive agent CNT (carbon nanotubes), NMP (N-methyl-2-pyrrolidone), LFP (lithium iron phosphate), and the positive electrode lithium supplementing agent prepared in Examples 13-32 and 34-40. This slurry was then coated to prepare the positive electrode sheet. The lithium supplementing material accounted for 1%, the lithium iron phosphate material for 90%, the binder for 4%, and the conductive agent for 5%.

[0411] Alternatively, the binder PVDF (polyvinylidene fluoride), the conductive agent CNT (carbon nanotubes), NMP (N-methyl-2-pyrrolidone), and NMC811 (LiNi) can be used. 0.8 Co 0.1 Mn 0.1 O2) was combined with the positive electrode lithium replenishing agent prepared in Examples 33 and 41 above to form a positive electrode slurry for coating, and a positive electrode sheet was prepared. The lithium replenishing material accounted for 1%, lithium iron phosphate material accounted for 90%, binder accounted for 4%, and conductive agent accounted for 5%.

[0412] Button cell test: The above positive electrode sheet was punched into small round pieces and assembled into a button cell in a glove box. The glove box environment was: water <0.1ppm, oxygen <1ppm. The counter electrode was a lithium sheet. The electrolyte was a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) in a volume ratio of 1:1:1, with 1.0mol / L LiPF6 as the solute. The assembled button cell was tested using the Blue Electric System to measure the specific capacity of the materials.

[0413] Full cell fabrication: The above-mentioned positive electrode sheets are stacked in a Z-shape, alternating between negative electrode-separator-positive electrode-separator-negative electrode, with each cell containing 7 positive electrodes and 8 negative electrodes; each cell is injected with 5.8g of electrolyte; then, the cells undergo chemical decomposition, aging, and capacity testing. The negative electrode is made of graphite material, with the mass ratio of graphite, conductive carbon black, and SBR (styrene-butadiene rubber) being 96:2:2.

[0414] Electrochemical performance testing:

[0415] Capacity test of positive electrode after lithium replenishment: The positive electrode was assembled into a coin cell and tested using a Xinwei battery cabinet. The initial charge capacity and discharge capacity were measured when the charging voltage was 2.5-4.3V and the charging current was 0.5C.

[0416] Lithium-ion battery cell gas generation test

[0417] The lithium-filled cells assembled with the positive electrode lithium-filling agents of Examples 13-41 above were subjected to in-situ differential electrochemical mass spectrometry (IECMS). The gas production during the first charging cycle (formation stage) was measured within a voltage window of 2.0V–4.3V and a charging current of 0.1C. After the battery was charged to 4.3V at a constant voltage and stored at 60°C for 10 days, its gas production was tested again.

[0418] The test results are shown in Table 3.

[0419] Table 3

[0420] In summary, the positive electrode lithium replenisher provided in this application can effectively alleviate gas generation and improve the lithium replenishment effect. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

[0421] 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

A positive electrode lithium replenishing agent, characterized in that, It includes a lithium-replenishing core and a carbon coating layer covering the surface of the lithium-replenishing core; The Raman spectrum of the positive electrode lithium supplement has a shift range of 1560–1580 cm⁻¹. -1 The G peak and displacement range are 1350–1370 cm. -1 The D peak and displacement range are 655–675 cm. -1 Peak 1; Among them, the peak intensity IG of peak G, the peak intensity ID of peak D, and the peak intensity I1 of peak 1 satisfy: 0.85 <IG / ID<1.25,9<IG / I1<50,9<ID / I1<50。 The positive electrode lithium replenishing agent according to claim 1 is characterized in that, The positive electrode lithium replenishing agent is obtained by sintering a mixture including a lithium replenishing core, a carbon source and a coating additive; The coating additive includes compounds capable of thermally decomposing to generate gaseous carbohalogens and halogen radicals, wherein the thermal decomposition temperature is not higher than the sintering temperature. And / or, the chemical composition of the lithium-supplementing core is Li a M b O c M includes one or more of Fe, Ni, Mn, Cu, Zn, Co, Cr, Zr, Sb, Ti, V, Mo, and Sn, where 1 < a ≤ 8, 0 < b ≤ 1, and 0 < c < 7. The positive electrode lithium replenishing agent according to claim 2 is characterized in that, The molecular weight of the coating additive is <600; And / or, the coating additive includes one or more of hexachlorobenzene, hexabromobenzene, chlorobenzene, bromobenzene, dichlorobenzene, and dibromobenzene; And / or, the carbon source includes one or more of carbon black, graphene, carbon nanotubes, fullerene, sucrose, glucose, pitch, polydopamine, resorcinol, formaldehyde, starch, sucrose, sodium carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, tannic acid, polyvinyl alcohol, polypyrrole, vitamin C, polyethylene glycol, anthracene, or aniline; and / or, the mass ratio of the lithium-supplementing core, the carbon source, and the coating additive is 1:x:y, 0 <x<10%,0<y<10%。 The positive electrode lithium replenishing agent according to any one of claims 1-3 is characterized in that, The D50 particle size of the positive electrode lithium replenishing agent is 10–30 μm; And / or, the thickness of the carbon coating layer is 100–200 nm; and / or, the specific surface area of ​​the positive electrode lithium supplement is 0.3–0.8 m². 2 / g. A method for preparing the positive electrode lithium replenishing agent according to any one of claims 1-4, characterized in that, Includes the following steps: The lithium-replenishing core, carbon source, and coating additives are mixed to obtain a mixture; the mixture is then sintered to obtain a positive electrode lithium-replenishing agent. The coating additive includes compounds capable of thermally decomposing to generate gaseous carbohalogen free radicals and halogen free radicals, wherein the thermal decomposition temperature is not higher than the sintering temperature. The preparation method according to claim 5 is characterized in that, The sintering process is carried out at a temperature of 80–1000°C for 3–15 hours. A positive electrode lithium replenishing agent, characterized in that, include: The core includes a lithium supplementation core; A coating layer that covers the core, the coating layer comprising anoxic compounds. The positive electrode lithium replenishing agent according to claim 7 is characterized in that, The oxygen-deficient compound includes at least one of an oxygen-deficient metallic compound and an oxygen-deficient nonmetallic compound. The positive electrode lithium replenishing agent according to claim 8 is characterized in that, The oxygen-deficient metal compound includes Al2O 3-x MgO 1-y and TiO 2-z At least one of them; wherein, 0 <x<3,0<y<1,0<z<2; And / or, the oxygen-deficient nonmetallic compound includes SiO₂ 2-a ; among which, 0 <a<2。 The positive electrode lithium replenishing agent according to any one of claims 7 to 9 is characterized in that, Based on the positive electrode lithium replenishment agent, the mass percentage m1 of the oxygen-deficient compound satisfies: 0 < m1 ≤ 10%; preferably, the mass percentage m1 of the oxygen-deficient compound satisfies: 0.1% < m1 ≤ 5%. And / or, the D of the oxygen-deficient compound 50 The range is 20nm to 200nm; And / or, the D of the lithium-replenishing core 50 The thickness is 1μm to 20μm; and / or, the lithium replenishment core comprises a binary lithium compound or a ternary lithium compound. And / or, the lithium replenishment core includes at least one of Li5FeO4, Li2NiO2, and Li2O2; And / or, the coating layer further includes a conductive material; the conductive material includes at least one of conductive carbon material and conductive non-carbon material. The positive electrode lithium replenishing agent according to claim 10 is characterized in that, The water contact angle of the conductive material is 90°≤θ≤160°; And / or, the mass percentage m2 of the conductive material satisfies: 0 < m2 ≤ 10%. A method for preparing the positive electrode lithium replenishing agent according to any one of claims 7 to 11, characterized in that, include: A mixture is obtained by mixing a lithium-replenishing core and an oxygen-deficient compound, and the mixture is then heat-treated to obtain the positive electrode lithium replenishing agent. The preparation method according to claim 12 is characterized in that, The step of mixing the lithium-replenishing core and the oxygen-deficient compound to obtain a mixture further includes adding a conductive material; And / or, the heat treatment control parameters include: The heat treatment temperature is 20℃~200℃, and / or the heat treatment time is 1h~6h. The preparation method according to any one of claims 12 to 13 is characterized in that, The oxygen-deficient compound was prepared using the following method: The oxygen-deficient compound is obtained by mixing a metal oxide or non-metal oxide with a reducing agent and then annealing it; wherein the annealing parameters include at least one of the following: (a) The annealing temperature is 500℃~1000℃; (b) Annealing time is 6h to 15h; (c) Annealing is carried out under an inert atmosphere. A positive electrode sheet, characterized in that, The device includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector. The positive active material layer includes the positive lithium supplement agent according to any one of claims 1 to 4, or the positive lithium supplement agent prepared by the preparation method according to claims 5 or 6, or the positive lithium supplement agent according to any one of claims 7-11, or the positive lithium supplement agent prepared by the preparation method according to any one of claims 12-14. The positive electrode sheet according to claim 15 is characterized in that, The positive electrode sheet further includes a positive electrode active material; the positive electrode active material includes LiFePO4 and LiNi. c Co d Mn 1-c-d O2, wherein at least one of 0.3≤c<1 and 0≤d≤0.

5. A battery characterized in that, Includes the positive electrode sheet as described in claim 15 or 16. An electrical appliance, characterized in that, Includes the battery as described in claim 17.

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