A self-supplementing lithium ternary material, its preparation method and application

Abstract

This invention discloses a self-lithiated ternary material, its preparation method, and its applications. The self-lithiated ternary material has a core-shell structure, with the core being the ternary material and the shell comprising two coating layers: lithium-rich nickel oxide (Li₂NiO₂) and a carbon coating layer, from the inside out. In this invention, Li₂NiO₂ is uniformly coated on the surface of the ternary material, avoiding the possibility of gelation caused by excessively high residual alkali content in the slurry due to the addition of lithium supplementer. Furthermore, the dense carbon coating layer also prevents contact between Li₂NiO₂ and PVDF, thereby improving the material's processing performance and extending the slurry window period. This invention achieves thorough and uniform mixing of the positive electrode lithium supplementer and the ternary material, preventing lithium plating during charging. In addition, during charge and discharge, the dense carbon coating layer also prevents contact between the ternary material, the lithium supplementer, and the electrolyte, thereby reducing side reactions and improving cycle performance and storage performance.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a self-replenishing lithium-type ternary material, its preparation method, and its application. Background Technology

[0002] During the first charge of a lithium-ion battery, the organic electrolyte undergoes a reduction and decomposition reaction on the surface of negative electrode materials such as graphite, forming a solid electrolyte interphase (SEI) film. The formation of this SEI film leads to the consumption of lithium in the positive electrode active material, and this process is irreversible. Simultaneously, both the formation and consumption of the SEI film require the consumption of lithium in the positive electrode, resulting in a low coulombic efficiency during the first charge and discharge cycle, thereby reducing the capacity and energy density of the lithium-ion battery.

[0003] As consumers demand increasingly longer driving ranges for electric vehicles and national subsidies are gradually decreasing or even being eliminated, the energy density requirements for power batteries are also rising. Currently, the energy density of graphite anode materials has essentially reached its limit, thus necessitating the development of next-generation anode materials. Silicon-based materials, due to their high specific capacity (theoretical specific capacity 4200 mAh / g, far exceeding that of graphite anodes), are currently a hot research topic for next-generation anode materials. However, compared to graphite anodes, silicon-based anodes exhibit greater irreversible capacity and poorer cycle stability, severely impacting battery energy density and lifespan. Literature reports that graphite materials experience 5–10% irreversible capacity loss during the first charge-discharge cycle, while high-capacity silicon anodes suffer even greater initial capacity loss, approximately 15–35%.

[0004] To address the issue of lithium depletion at the negative electrode reducing reversible capacity and energy density, improving cycle performance, extending battery life, and promoting the industrial application of silicon-based negative electrode materials, pre-lithiation has been considered an effective technology. Among these technologies, positive electrode lithium replenishment is the most promising for industrial application due to its high safety and the fact that it does not require changes to existing battery manufacturing processes. Lithium-rich nickel oxide (Li₂NiO₂) (LNO) is one of the main commercially available positive electrode lithium replenishment additives, and it has been verified or applied in small batches by major battery manufacturers. Although LNO only needs to be added during the positive electrode slurry mixing process and does not significantly alter the original cell manufacturing process, the high residual alkali content on the LNO surface means that a single addition during slurry mixing may cause local residual alkali concentrations to exceed the tolerance range of the PVDF binder, leading to localized gelation and eventually complete gelation, requiring the addition of organic acids for treatment. Furthermore, uneven dispersion of LNO during slurry mixing can cause localized lithium plating during charging, deteriorating the cell's electrical performance and posing safety hazards. Finding a solution for LNO to achieve lithium replenishment while maintaining processing performance, electrical performance, and safety is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a self-replenishing lithium-type ternary material and its preparation method.

[0006] The self-lithiated ternary material provided by this invention has a core-shell structure. Its core is a ternary material, and the shell contains two coating layers, which are lithium-rich nickel oxide (Li2NiO2) and a C coating layer from the inside to the outside. The lithium-rich nickel oxide (Li2NiO2) accounts for 1.0-5.0% of the total weight of the self-lithiated ternary material, and the C coating layer accounts for 1.0-2.0% of the total weight of the self-lithiated ternary material.

[0007] The above-mentioned self-lithiated ternary material is prepared by a method including the following steps:

[0008] 1) Mix the ternary material with water in a certain proportion to form a slurry, stir, filter, dry the resulting filter cake, pulverize it, and obtain ternary powder.

[0009] 2) Heat the obtained ternary powder to a set temperature, sinter, and cool to room temperature to obtain the heat-treated ternary powder;

[0010] 3) The heat-treated ternary powder is mixed with a lithium source and a carbon source, heated to a set temperature, sintered, and cooled to room temperature to obtain a self-replenishing lithium-type ternary material.

[0011] In step 1) of the above method, the chemical formula of the ternary material is LiNi. x Co y M 1-x-y O2, wherein M is at least one of Mn, Al, W, Zr, Mg, B, Nb, Ta, Mo, La and Ti, 0.33≤x≤1.0, 0≤y≤0.33;

[0012] In one embodiment of the present invention, the ternary material is LiNi. 0.83 Co 0.12 Mn 0.05 O2;

[0013] The water may specifically be deionized water.

[0014] The ternary material is mixed with water at a mass ratio of 1:0.3 to 2, and the stirring time can be 24 to 120 hours, specifically 24 to 48 hours, 48 ​​to 120 hours, 24 hours, 48 ​​hours, or 120 hours.

[0015] The drying process can be vacuum drying, and the vacuum drying time can be 5 to 24 hours, specifically 15 hours.

[0016] In one embodiment of the present invention, during the first 2 hours of vacuum drying, the gas is replaced every 0.5 hours, and the gas may be one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0017] In step 2) of the above method, the sintering is carried out in dry air or an oxygen atmosphere;

[0018] The sintering temperature of the ternary powder is 500-700℃, and the sintering time is 2-10h;

[0019] In step 3) of the above method, the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium peroxide, lithium nitrate, lithium sulfate, lithium citrate, lithium oxalate, and lithium ethoxide.

[0020] The carbon source is one or more of glucose, acetylene black, PVDF, PTFE, sucrose, ascorbic acid, citric acid, and polyvinyl alcohol;

[0021] Ternary powder and lithium source according to Ni 2+ The mixture is prepared by mixing Li at a molar ratio of 1:1.7 to 2.2, and the amount of carbon source added is based on the mass of carbon elements, accounting for 1 to 3 wt.% of the ternary powder.

[0022] The sintering temperature of the ternary powder, lithium source, and carbon source mixture is 500–800℃, and the sintering time is 5–24 hours.

[0023] The sintering is carried out in an inert atmosphere.

[0024] The inert atmosphere is one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0025] The application of the aforementioned self-replenishing lithium-type ternary materials in the preparation of lithium-ion batteries also falls within the scope of protection of this invention.

[0026] The present invention also provides a lithium-ion battery, wherein the lithium-ion battery uses the above-mentioned self-replenishing lithium-type ternary material as the positive electrode material.

[0027] The beneficial effects of this invention are:

[0028] (1) This invention utilizes the characteristic that ternary materials are extremely sensitive to moisture. When exposed to water, the surface structure is reconstructed, generating a uniform layer of NiOOH. Subsequently, NiOOH is decomposed into NiO by high-temperature calcination. NiO reacts with lithium sources such as lithium oxide in an inert atmosphere to generate lithium-rich nickel oxide Li2NiO2, thereby obtaining a ternary material uniformly coated with Li2NiO2. A carbon source is introduced during the reaction process of NiO and lithium source, and a dense carbon coating layer is generated in situ on the surface of the self-lithiated ternary material after high-temperature calcination, thus obtaining a ternary material with a double coating layer.

[0029] (2) The self-lithiating ternary material prepared by this invention can be applied without changing the existing ternary cathode slurry mixing process, and can also achieve lithium replenishment, avoiding problems such as slurry gelation and lithium plating during charging caused by uneven slurry dispersion. Since Li2NiO2 is uniformly coated on the surface of the ternary material, it can avoid the possibility of gelation caused by excessive residual alkali content in the slurry due to the addition of lithium replenishing agent. In addition, the dense carbon coating layer can also block the contact between Li2NiO2 and PVDF, thereby improving the processing performance of the material and extending the slurry window period. The uniform coating of Li2NiO2 on the surface of the ternary material achieves full and uniform mixing between the cathode lithium replenishing agent and the ternary material, avoiding lithium plating during charging. In addition, during the charging and discharging process, the dense carbon coating layer can also block the contact between the ternary material, the lithium replenishing agent and the electrolyte, thereby reducing the occurrence of side reactions and improving cycle performance and storage performance. Since carbon has high electronic conductivity, uniform carbon coating can also improve the rate performance of the ternary material.

[0030] (3) The equipment investment of the present invention is small, the process is simple and controllable, and the batch stability of the product is good. Attached Figure Description

[0031] Figure 1 The self-lithiated single-crystal ternary material LiNi prepared in Example 1 of this invention 0.83 Co 0.12 Mn 0.05 SEM image of O2.

[0032] Figure 2 For the single-crystal ternary material LiNi in Comparative Example 1 0.83 Co 0.12 Mn 0.05 SEM image of O2. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0035] The first aspect of this invention discloses a self-replenishing lithium-type ternary material, which has a core-shell structure. The core is a ternary material, and the shell includes two coating layers, which are lithium-rich nickel oxide (Li2NiO2) and C coating layers from the inside to the outside.

[0036] The second aspect of this invention discloses a method for preparing a self-replenishing lithium-type ternary material, specifically including the following steps:

[0037] S1. The ternary material and deionized water are mixed into a slurry in a certain proportion, stirred at a uniform speed, and then filtered. The resulting filter cake is placed in a vacuum oven to dry. After drying, the filter cake is ground into powder using a mortar and pestle.

[0038] S2, the ternary powder obtained in step S1 is placed in dry air or oxygen atmosphere and heated to the set temperature for sintering. After sintering, it is naturally cooled to room temperature to obtain the heat-treated ternary powder.

[0039] S3. The heat-treated ternary powder is uniformly mixed with lithium source and carbon source, and then heated in an inert atmosphere to a set temperature for sintering. After sintering, it is naturally cooled to room temperature to obtain self-replenishing lithium-type ternary material.

[0040] This invention utilizes the extreme sensitivity of ternary materials to moisture. Upon contact with water, the surface structure is restructured, generating a uniform layer of NiOOH. Subsequently, high-temperature calcination decomposes the NiOOH into NiO. The NiO reacts with lithium sources such as lithium oxide in an inert atmosphere to generate lithium-rich lithium nickel oxide (Li₂NiO₂), which uniformly coats the ternary material. Simultaneously, a carbon source is introduced, and after high-temperature calcination, a dense carbon coating layer is formed in situ on the surface of the self-lithiating ternary material. Because Li₂NiO₂ uniformly coats the ternary material surface, it avoids the possibility of gelation caused by excessively high residual alkali content in the slurry due to the addition of lithium supplementers. Furthermore, the dense carbon coating layer also prevents contact between Li₂NiO₂ and PVDF, thereby improving the material's processing performance and extending the slurry window period. The uniform coating of Li₂NiO₂ on the ternary material surface ensures thorough and uniform mixing of the positive electrode lithium supplementer and the ternary material, preventing lithium plating during charging. Furthermore, during charge and discharge, the dense carbon coating can also prevent contact between the ternary material, the lithium replenisher, and the electrolyte, thereby reducing side reactions and improving cycle performance and storage performance. Due to the high electronic conductivity of carbon, uniform carbon coating can also improve the rate performance of ternary materials.

[0041] Furthermore, the chemical formula of the ternary material in step S1 is LiNi. x Co y M 1-x-y O2, wherein M is one of Mn, Al, W, Zr, Mg, B, Nb, Ta, Mo, La and Ti, 0.33≤x≤1.0, 0≤Co≤0.33; the morphology of the ternary material is composed of one or more of polycrystalline, single crystal, near-single crystal and small-particle polycrystalline.

[0042] Furthermore, in step S1, the ternary material and deionized water are mixed at a ratio of 1:0.3 to 2, and the stirring time is 24 to 120 hours.

[0043] Furthermore, in step S1, the vacuum drying time is 5 to 24 hours. During the first 2 hours of drying, the gas is replaced every 0.5 hours. The gas is one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0044] Furthermore, in step S2, the sintering temperature of the ternary powder is 500-700℃, and the sintering time is 2-10h.

[0045] Furthermore, in step S3, the lithium source is one or a mixture of lithium hydroxide, lithium carbonate, lithium oxide, lithium peroxide, lithium nitrate, lithium sulfate, lithium citrate, lithium oxalate, and lithium ethoxide.

[0046] The carbon source is one or more of glucose, acetylene black, PVDF, PTFE, sucrose, ascorbic acid, citric acid, and polyvinyl alcohol;

[0047] Furthermore, in step S3, the ternary powder and the lithium source are mixed according to Ni... 2+ The mixture is prepared by mixing Li at a molar ratio of 1:1.7 to 2.2, and the amount of carbon source added is based on the mass of carbon elements, accounting for 1 to 3 wt.% of the mass of the ternary powder.

[0048] Furthermore, in step S3, the sintering temperature of the mixture of ternary powder, lithium source and carbon source is 500-800℃, and the sintering time is 5-24h, wherein the inert atmosphere is one or more of nitrogen, helium, neon, argon, krypton and xenon.

[0049] The present invention also discloses the application of the self-replenishing lithium-type ternary material prepared according to the above method in lithium-ion batteries.

[0050] The technical solution of the present invention will be described more clearly and completely below with reference to specific embodiments.

[0051] The single-crystal ternary material LiNi in the following embodiments 0.83 Co 0.12 Mn 0.05 O2 is prepared using the following method: 100g of precursor D... 50 Ni is 3.2 μm 0.83 Co 0.12 Mn 0.05 (OH)₂ and LiOH are mixed evenly at a molar ratio of 1:1.02 and placed in a high-temperature sintering furnace. In an oxygen atmosphere, the mixture is first heated to 500℃ for pre-sintering for 5 hours, then heated to 860℃ and held for 15 hours. After the reaction is complete, the mixture is cooled and then subjected to air-jet grinding to control the particle size D. 50 The value is 3.5 ± 1 μm, which yields LiNi. 0.83 Co 0.12 Mn0.05 O2 single crystal material.

[0052] Polycrystalline LiNi 0.88 Co 0.07 Mn 0.05 O2 is prepared using the following method: 100g of precursor D... 50 Ni is 10.0 μm 0.88 Co 0.07 Mn 0.05 (OH)₂ and LiOH are mixed evenly at a molar ratio of 1:1.01 and placed in a high-temperature sintering furnace. Under an oxygen atmosphere, the mixture is first heated to 500℃ for pre-sintering for 5 hours, then heated to 700℃ and held for 15 hours. After the reaction is complete, the mixture is cooled and mechanically ground to obtain LiNi. 0.88 Co 0.07 Mn 0.05 O2 polycrystalline materials.

[0053] Example 1

[0054] Take 50g LiNi 0.83 Co 0.12 Mn 0.05 O2 single-crystal ternary material was mixed with 50g of deionized water at a mass ratio of 1:1 and stirred uniformly with a stirring paddle for 48 hours. The mixture was then filtered to obtain a filter cake, which was placed in a vacuum oven at 150℃ and dried for 15 hours. For the first 2 hours of drying, nitrogen was used as the purging gas, and the gas was replaced every 0.5 hours. After drying, the filter cake was ground into powder using a mortar and pestle and then passed through a 200-mesh sieve.

[0055] The LiNi obtained above 0.83 Co 0.12 Mn 0.05 O2 single crystal powder was heated from room temperature to 600℃ in an oxygen atmosphere and held at that temperature for 5 hours, then naturally cooled to room temperature to obtain heat-treated LiNi. 0.83 Co 0.12 Mn 0.05 O2 monocrystalline powder.

[0056] XPS was used to measure the heat-treated LiNi 0.83 Co 0.12 Mn 0.05 O2 single crystal powder contains divalent nickel (Ni). 2+ Content, LiNi 0.83 Co 0.12 Mn 0.05 O2 and lithium oxide according to Ni 2+Li was mixed in a molar ratio of 1:1.9, yielding 0.24 g of lithium oxide. 2.5 g of glucose was added, with the glucose amount calculated by mass of carbon, representing 2% of the ternary powder mass. The mixture was heated to 650 °C for 12 hours under a nitrogen atmosphere and then allowed to cool naturally to room temperature, yielding self-lithiated LiNi. 0.83 Co 0.12 Mn 0.05 O2 single-crystal ternary materials. Self-lithiated ternary single-crystal LiNi was measured using XRD. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 1.74% (based on the total weight of the self-lithiated ternary single crystal material) of positive electrode lithium supplementer Li2NiO2, and the C coating content is 1.61% (based on the total weight of the self-lithiated ternary single crystal material).

[0057] The self-lithiated ternary single crystal material LiNi in this embodiment is used. 0.83 Co 0.12 Mn 0.05 O2, conductive agent CNTs, and binder PVDF are mixed in a mass ratio of 98:1:1 using NMP as a solvent to form a slurry, with the solid content controlled at 70%. This slurry is then coated onto current collector aluminum foil, with a single-sided density controlled at 215 g / m². 2 The compacted density of the electrode sheet after roller pressing is 3.60 g / cm³. 3 A 3Ah pouch cell was assembled using a graphite negative electrode with an NP ratio of 1.13, a 1M LiPF6 solution as the electrolyte, and Cell Gard 2300 as the separator. The electrochemical performance of the product is shown in Table 1.

[0058] Comparative Example 1

[0059] 50g of single-crystal ternary material LiNi 0.83 Co 0.12 Mn 0.05 O2 and 2.5g of glucose (the amount of glucose added is based on the mass of carbon, accounting for 2% of the mass of the ternary powder) are heated to 650℃ and held for 12 hours in a nitrogen atmosphere, then allowed to cool naturally to room temperature to obtain carbon-coated LiNi. 0.83 Co 0.12 Mn 0.05 O2 single-crystal ternary material. The carbon-coated ternary material was mixed with conductive agents (CNTs) and binders (PVDF) at a mass ratio of 98:1:1, using NMP as a solvent to form a slurry. Other steps were the same as in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0060] Comparative Example 2

[0061] Take the carbon-coated single-crystal ternary material LiNi from Comparative Example 1. 0.83 Co0.12 Mn 0.05 O2, positive electrode lithium supplement Li2NiO2, conductive agent CNTs, and binder PVDF were mixed in a mass ratio of 96.26:1.74:1:1 using NMP as solvent to form a slurry. Other steps were the same as in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0062] Example 2

[0063] The slurry stirring time in Example 1 was extended to 120 hours, while other steps remained the same as in Example 1. XRD analysis was used to determine the self-lithiated ternary single-crystal material LiNi. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 4.52% positive electrode lithium supplement Li2NiO2.

[0064] The battery cells were assembled according to the battery manufacturing process in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0065] Example 3

[0066] The slurry stirring time in Example 1 was shortened to 24 hours, while other steps remained the same as in Example 1. XRD analysis was used to determine the self-lithiated ternary single-crystal material LiNi. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 1.13% of the positive electrode lithium supplement Li2NiO2.

[0067] The battery cells were assembled according to the battery manufacturing process in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0068] Comparative Example 3

[0069] The slurry stirring time in Example 1 was extended to 170 hours, while other steps remained the same as in Example 1. The self-lithiated ternary single-crystal material LiNi was measured using XRD. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 6.50% of the positive electrode lithium supplement Li2NiO2.

[0070] The battery cells were assembled according to the battery manufacturing process in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0071] Comparative Example 4

[0072] The slurry stirring time in Example 1 was shortened to 5 hours, while other steps remained the same as in Example 1. XRD analysis was used to determine the self-lithiated ternary single-crystal material LiNi. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 0.15% of the positive electrode lithium supplement Li2NiO2.

[0073] The battery cells were assembled according to the battery manufacturing process in Example 1. The electrochemical performance of the product is detailed in Table 1.

[0074] Comparative Example 5

[0075] The amount of glucose added in Example 1 was reduced to 0.5%, while other steps remained the same as in Example 1. The battery cells were assembled according to the battery fabrication process in Example 1, and the electrochemical performance of the product is detailed in Table 1.

[0076] Comparative Example 6

[0077] The amount of glucose added in Example 1 was increased to 4.0%, and the other steps were the same as in Example 1. The battery cells were assembled according to the battery manufacturing process in Example 1, and the electrochemical performance of the product is detailed in Table 1.

[0078] Example 4

[0079] The single-crystal ternary material LiNi from Example 1 0.83 Co 0.12 Mn 0.05 O2 was replaced with polycrystalline LiNi 0.88 Co 0.07 Mn 0.05 O2, other steps are the same as in Example 1. The self-lithiated ternary single-crystal material LiNi was measured by XRD. 0.83 Co 0.12 Mn 0.05 The O2 surface contains 1.94% of the positive electrode lithium supplement Li2NiO2.

[0080] The self-lithiated ternary single crystal material LiNi in this embodiment is used. 0.88 Co 0.07 Mn 0.05 O2, conductive agent CNTs, and binder PVDF are mixed in a mass ratio of 98:1:1 using NMP as a solvent to form a slurry, with the solid content controlled at 70%. This slurry is then coated onto current collector aluminum foil, with a single-sided density controlled at 215 g / m². 2 The compacted density of the electrode sheet after roller pressing is 3.60 g / cm³. 3 A 3Ah pouch cell was assembled using a graphite negative electrode with an NP ratio of 1.13, a 1M LiPF6 solution as the electrolyte, and Cell Gard 2300 as the separator. The electrochemical performance of the product is shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] Note: The normal viscosity range for the positive electrode paste is 4000–8000 Pa·s.

[0085] As can be seen from Table 1, compared with Comparative Example 1, the self-lithiated single-crystal ternary material LiNi prepared using this invention in Example 1... 0.83 Co 0.12 Mn 0.05 Compared to conventional single-crystal ternary materials, O2-based ternary materials for full-cell batteries exhibit a 2.8 mAh / g increase in specific capacity at 0.33C, a 173-cycle improvement at 45℃ and 1C, while maintaining essentially unchanged high-temperature storage performance and slurry viscosity. Furthermore, from... Figure 1 and Figure 2 The comparison also shows that Figure 2 The surface of the medium sample is relatively rough, while Figure 1 The surface of the medium-sized particles is relatively smooth, mainly because the surface morphology of the ternary material in Example 1 was changed after water washing and carbon coating modification. Compared with Comparative Example 2, the 0.33C specific capacity of the full-cell ternary material is basically the same, and the 1C specific capacity of the former is 1.1 mAh / g higher than that of the latter, indicating that the ternary material prepared by the present invention not only improves capacity performance but also improves rate performance. In addition, because the self-lithiating material prepared by the present invention is coated with a dense carbon layer, its high-temperature storage performance is improved, and the capacity retention rate is increased by 3.4% compared with the conventional cell prepared by adding positive electrode lithium supplementation additive LNO (results of comparison between Example 1 and Comparative Example 2). Compared with Comparative Examples 3 and 4, the slurry uniform stirring time of Examples 1-3 is controlled at 24-120h, and the electrical performance of the obtained samples is better (stirring time is related to Li2NiO2 content, and Li2NiO2 content increases with the extension of stirring time). When the stirring time is higher than 120h, the Li2NiO2 content of the obtained sample is too high, and its specific capacity decreases. When the stirring time is less than 24 hours, the Li2NiO2 content of the obtained sample is too low, and its cycling performance deteriorates. Compared with Comparative Examples 5 and 6, Example 1, with a carbon source addition amount in the range of 1–3 wt.%, yielded samples with lower residual alkali and better electrochemical performance. However, with a carbon source addition amount below 1 wt.%, the residual alkali of the obtained sample increased, the processing performance deteriorated, and the storage performance worsened. When the carbon source addition amount exceeded 3 wt.%, the specific capacity of the obtained sample decreased.

[0086] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing self-lithiated ternary materials, comprising the following steps: 1) mixing ternary materials with water in a certain proportion to form a slurry, stirring, filtering, drying the resulting filter cake, pulverizing, and obtaining ternary powder; 2) Heat the obtained ternary powder to a set temperature, sinter, and cool to room temperature to obtain the heat-treated ternary powder; 3) The heat-treated ternary powder is mixed with a lithium source and a carbon source, heated to a set temperature, sintered, and cooled to room temperature to obtain a self-lithiated ternary material; In step 1), the chemical formula of the ternary material is LiNi. x Co y M 1-x-y O2, wherein M is at least one of Mn, Al, W, Zr, Mg, B, Nb, Ta, Mo, La and Ti, 0.33≤x≤1.0, 0≤y≤0.33; In step 2), the sintering is carried out in dry air or an oxygen atmosphere; The sintering temperature of the ternary powder is 500~700℃, and the sintering time is 2~10h; The lithium-supplemented ternary material prepared by the method has a core-shell structure. Its core is a ternary material, and its shell contains two coating layers, which are lithium-rich nickel oxide (Li2NiO2) and C coating layers from the inside to the outside.

2. The method for preparing self-lithiated ternary materials according to claim 1, characterized in that: In step 1), the ternary material is mixed with water at a mass ratio of 1:0.3~2, and the stirring time is 24~120h.

3. The method for preparing self-lithiated ternary materials according to claim 1, characterized in that: In step 3), the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium oxide, lithium peroxide, lithium nitrate, lithium sulfate, lithium citrate, lithium oxalate, and lithium ethoxide. The carbon source is one or more of glucose, acetylene black, PVDF, PTFE, sucrose, ascorbic acid, citric acid, and polyvinyl alcohol.

4. The method for preparing self-lithiated ternary materials according to claim 1, characterized in that: Ternary powder and lithium source according to Ni 2+ The mixture is prepared by mixing Li in a molar ratio of 1:1.7~2.

2. The amount of carbon source added is based on the mass of carbon elements, which accounts for 1~3 wt.% of the ternary powder.

5. The method for preparing self-lithiated ternary materials according to claim 1, characterized in that: The sintering temperature of the ternary powder, lithium source and carbon source mixture is 500~800℃, and the sintering time is 5~24h; The sintering is carried out in an inert atmosphere.

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