Positive electrode lithium supplement additive and preparation method and application thereof

Abstract

The invention discloses a positive electrode lithium supplement additive and a preparation method and application thereof. The molecular formula of the lithium supplement additive for the positive electrode of the lithium ion battery is Li2NixZn (1-x) O2, and 0.8 lt; xlt; 1. The preparation method provided by the invention comprises the following steps: firstly, obtaining a precursor metal hydroxide NixZn (1-x) (OH) 2 of the lithium supplement additive through a coprecipitation method, and then mixing the precursor metal hydroxide NixZn (1-x) (OH) 2 with a lithium source and calcining to obtain the anode lithium supplement additive material Li2NixZn (1-x) O2. The bimetal lithium supplement agent provided by the invention has better structural stability and chemical stability, and the preparation process is simple and easy for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a positive electrode lithium supplement additive material and a preparation method thereof, and a lithium battery. Background Art

[0002] Lithium-ion batteries have occupied most of the market for electronic devices and power batteries in the consumer field due to their many advantages such as high voltage, high energy density and long cycle life. During the first charging process of lithium-ion batteries, the electrolyte decomposes to form a solid electrolyte membrane (SEI membrane) on the electrode surface, which converts the lithium in the positive electrode material into lithium carbonate or lithium alkoxide, ester salt, etc., resulting in an irreversible reduction in active lithium, reducing the initial efficiency of the material, and reducing the reversible capacity, that is, reducing the battery energy density.

[0003] In order to solve the problem of low initial efficiency, existing methods mainly adopt positive electrode lithium replenishment and negative electrode lithium replenishment processes. Negative electrode lithium replenishment usually requires the use of highly active lithium powder or lithium foil, which not only has high requirements on equipment and working environment, but also has high risks and uneven lithium replenishment. Compared with the difficult and high-investment negative electrode lithium replenishment process, positive electrode lithium replenishment is safer. The typical positive electrode lithium replenishment process is to add a small amount of high-capacity positive electrode material to the positive electrode during the homogenization process. During the charging process, the excess Li element is released from these high-capacity positive electrode materials and embedded in the negative electrode to replenish the irreversible capacity of the first charge and discharge.

[0004] Li 2 NiO 2 (LNO) is a high-capacity lithium supplement additive, but Li 2 NiO 2 It has the disadvantages of poor stability and easy side reaction with electrolyte at high potential. 2 NiO 2 (LNO) is rationally modified to enable it to exert excellent lithium supplementation effect. Summary of the invention

[0005] The purpose of the present invention is to provide a positive electrode lithium supplement additive and its preparation method and application. The positive electrode lithium supplement additive provided by the present invention effectively compensates for the loss of active lithium in the positive electrode material caused by the formation of SEI film on the negative electrode, improves the capacity of the lithium battery, and has a simple preparation method, good material uniformity, and is suitable for industrial production.

[0006] To achieve the above object, the present invention provides the following technical solutions: In the first aspect, the present invention provides a lithium-ion battery positive electrode lithium supplement additive, the molecular formula of which is Li 2 Ni x Zn (1-x) O 2, where 0.8 <x<1。

[0007] Specifically, x may be 0.8, 0.85, 0.9 or 0.95, etc.

[0008] The present invention is to 2 NiO 2 The material is doped with Zn ions. Since metal Zn and Ni are elements in the same period, their radius is close to Ni. The addition of Zn can maintain the core Li of the lithium supplement additive. 2 NiO 2 Its own framework, so that the structure can be more stable during the bonding process.

[0009] In a second aspect, the present invention provides a method for preparing the lithium-ion battery positive electrode lithium supplement additive, comprising the following steps: S1, mixing a soluble metal salt mixed solution, an alkali solution and a complexing agent, and performing a coprecipitation reaction to obtain a precursor metal hydroxide Ni x Zn (1-x) (OH) 2 ; S2, the obtained precursor metal hydroxide Ni x Zn (1-x) (OH) 2 Mix with lithium source and sinter to obtain the positive electrode lithium supplement additive Li 2 Ni x Zn (1-x) O 2 .

[0010] In step S1, the soluble metal salt is a nickel salt and a zinc salt; preferably, the nickel salt is selected from a hydrate of nickel sulfate and / or a hydrate of nickel chloride; and the zinc salt is selected from a hydrate of zinc sulfate and / or a hydrate of zinc chloride.

[0011] In step S1, the total concentration of metal ions in the soluble metal salt mixed solution is 1-2 mol / L.

[0012] In step S1, the alkali is sodium hydroxide and / or potassium hydroxide. The concentration of the alkali solution is 2-4 mol / L.

[0013] In step S1, the complexing agent is ammonia water; the concentration of the ammonia water is 1-2 mol / L.

[0014] In step S1, the dosage of the alkali solution and the complexing agent can be controlled according to the pH and ammonia value requirements during the synthesis process.

[0015] In step S1, the coprecipitation reaction is carried out according to the following operation: Under protective atmosphere, a reaction bottom solution with a pH value of 11-12 and an ammonia concentration of 2-4 g / L was pumped into the reactor, and then a soluble metal salt mixed solution, an alkali solution and a complexing agent were pumped into the reactor at the same time. The reaction was started under the conditions of pH = 11-12, an ammonia concentration of 1.0-2.0 g / L, a temperature of 50-60 ° C, and a stirring intensity of 400-600 rpm. During the reaction, the pH range was controlled between 10.6 and 12, the ammonia concentration was kept unchanged, and the precursor particles grew. When the particle size D 50 When the particle size reaches 3-10 μm, the feeding is stopped, the particles are aged, and the particles are separated to obtain a lithium supplement additive precursor.

[0016] According to an embodiment of the present invention, the pH value in the seeding stage is controlled to be 11-12, which is conducive to the nucleation of the precursor, and the seeding time is 10-20 minutes. During the growth of the precursor particles, the pH is controlled between 10.6 and 12, which is conducive to the uniform and controllable growth of the precursor.

[0017] In step S2, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, and lithium oxide.

[0018] In step S2, the lithium source is added in an amount according to a (Ni+Zn):Li molar ratio of 1:1.0-2.0.

[0019] In step S2, the gas used for sintering is selected from one or more of nitrogen, argon, carbon monoxide, and hydrogen.

[0020] In step S2, the sintering conditions are: pre-sintering at 350-450°C for 3-5h, and then sintering at 600-700°C for 12-18h.

[0021] In a third aspect, the present invention provides a method for preparing a lithium-ion battery, including preparing a positive electrode slurry; The positive electrode slurry is prepared by the following steps: adding the positive electrode lithium supplement additive, the ternary positive electrode material, the conductive agent and the binder into a solvent to form a positive electrode slurry.

[0022] The mass ratio of the positive electrode lithium supplement additive to the ternary positive electrode material, the conductive agent, and the binder is x:(90-x):5:5, wherein 1≤x≤5, preferably 3:87:5:5.

[0023] In a fourth aspect, the present invention provides a lithium ion battery obtained by the preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention is for Li 2 NiO 2The material is doped with Zn ions, and the doping amount of Zn is reasonably controlled (it must be lower than the doping amount of Ni), which effectively avoids the destruction of Li due to excessive Zn doping. 2 NiO 2 Its own frame structure causes structural collapse during the charging and discharging process.

[0025] (2) The present invention adopts a coprecipitation method to prepare a nickel-zinc double hydroxide precursor, which is conducive to forming precursor particles with uniform particle size, uniform element distribution, good sphericity, high tap density, and moderate specific surface area. The precursor itself has excellent chemical stability and is also easier to store and transport.

[0026] (3) The present invention introduces ammonia as a complexing agent in the co-precipitation process of preparing the lithium supplement additive, which can effectively complex metal ions, slow down the disturbance of the precipitation equilibrium caused by the addition of raw materials, control the supersaturation of the precipitate in the solution, and reduce the rate of nucleation and growth, allowing the crystal to grow slowly, which is easy to control.

[0027] (4) The precursor provided by the present invention has uniform sphericity, which is conducive to sufficient mixing and contact with the lithium source, improves the uniformity of material element distribution, avoids the generation of impurities during the sintering process, and forms a target lithium supplement additive with higher purity.

[0028] In summary, the present invention is through Li 2 NiO 2 The material is doped with metal cations to construct a bimetallic element lithium supplement additive to achieve the purpose of stabilizing the bulk phase structure and effectively solve the existing Li 2 NiO 2 The material has the problems of poor bulk structure stability and poor surface structure stability; and the preparation process is simple and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Ni in Example 1 0.8 Zn 0.2 (OH) 2 Electron microscope photo magnified 20,000 times.

[0030] Figure 2 This is an electron microscope photograph of the lithium supplement additive in Example 1 magnified 20,000 times. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0033] Unless otherwise specified, the reagents, materials, instruments, etc. used in the following examples can be obtained from commercial sources.

[0034] Example 1 The specific preparation steps are as follows: (1) Use of NiSO 4 6H 2 O and ZnSO 4 6H 2 O Prepare a 2 mol / L mixed salt solution of Ni and Zn according to the predetermined molar ratio of Ni:Zn=0.8:0.2; use NaOH to prepare an alkali solution with a concentration of 4 mol / L; use concentrated ammonia water to dilute and prepare a complexing agent with a concentration of 1 mol / L; prepare a startup base solution with a pH of 11 and an ammonia concentration of 1 g / L; Keep the pH at 11.0 and the ammonia concentration at 1 g / L, pump in the mixed salt solution and alkali solution at the same time, and remove the seeds for 15 minutes; reduce the alkali solution flow rate to slowly reduce the pH to 10.6, and then keep the pH at 10.6 to stop feeding after the particle size of the lithium supplement precursor grows to about 3.5 μm; The reaction atmosphere was nitrogen, the reaction temperature was 55°C, and the stirring rate of the reactor was 500 rpm. The materials in the reactor were aged for 3 hours, and then solid-liquid separation, washing, drying, sieving, and demagnetization were performed to obtain Ni 0.8 Zn 0.2 (OH) 2 Lithium supplement additive precursor; (2) Ni 0.8 Zn 0.2 (OH) 2 The lithium supplement additive precursor and lithium hydroxide were mixed evenly according to the (Ni+Zn) / Li molar ratio of 1:1.95, sintered at 400°C for 4h in a nitrogen sintering atmosphere, then sintered at 700°C for 14h, and cooled to room temperature to obtain Li 2 Ni 0.8 Zn 0.2 O 2 Lithium supplements.

[0035] Example 2 The specific preparation steps are as follows: (1) Use of NiSO 4 6H 2 O and ZnSO 4 6H 2 O Prepare a 2 mol / L mixed salt solution of Ni and Zn according to a predetermined molar ratio of Ni:Zn=0.85:0.15, use NaOH to prepare an alkali solution with a concentration of 4 mol / L, and use concentrated ammonia water to dilute and prepare a complexing agent with a concentration of 1 mol / L; prepare a startup base solution with a pH of 11.5 and an ammonia concentration of 1.5 g / L; Keep the pH and ammonia concentration constant, pump in the mixed salt solution and alkali solution at the same time, and remove the seeds for 15 minutes; reduce the alkali solution flow rate to slowly reduce the pH to 10.7, and then keep the pH constant, stop feeding after the particle size of the lithium supplement precursor grows to about 5.0μm; The reaction atmosphere was nitrogen, the reaction temperature was 50°C, and the stirring rate of the reactor was 550 rpm. The materials in the reactor were aged for 3 hours, and then solid-liquid separation, washing, drying, sieving, and demagnetization were performed to obtain Ni 0.8 Zn 0.2 (OH) 2 Lithium supplement additive precursor; (2) Ni 0.85 Zn 0.15 (OH) 2 The lithium supplement additive precursor and lithium hydroxide were mixed evenly according to the (Ni+Zn) / Li molar ratio of 1:2.0, first sintered at 350°C for 6h in a nitrogen sintering atmosphere, then sintered at 750°C for 12h, and cooled to room temperature to obtain Li 2 Ni 0.85 Zn 0.15 O 2 Lithium supplements.

[0036] Example 3 The specific preparation steps are as follows: (1) Use of NiSO 4 6H 2 O and ZnSO 4 6H 2 O According to the predetermined molar ratio of Ni:Zn=0.9:0.1, a 2mol / L mixed salt solution of Ni and Zn is prepared, NaOH is used to prepare an alkali solution with a concentration of 4mol / L, and concentrated ammonia water is used to dilute and prepare a complexing agent with a concentration of 1mol / L; a start-up base solution with a pH of 11.7 and an ammonia concentration of 1.7g / L is prepared; Keep the pH and ammonia concentration constant, pump in the mixed salt solution and alkali solution at the same time, and remove the seeds for 10 minutes; reduce the alkali solution flow rate to slowly reduce the pH to 10.7, then keep the pH constant, stop feeding after the particle size of the lithium supplement precursor grows to about 6.5μm; The reaction atmosphere was nitrogen, the reaction temperature was 50°C, and the stirring rate of the reactor was 550 rpm. The materials in the reactor were aged for 3 hours, and then solid-liquid separation, washing, drying, sieving, and demagnetization were performed to obtain Ni 0.9 Zn 0.1 (OH) 2 Lithium supplement additive precursor; (2) Ni 0.9 Zn 0.1 (OH) 2The lithium supplement additive precursor and lithium hydroxide were mixed evenly according to the (Ni+Zn) / Li molar ratio of 1:2.0, first sintered at 450°C for 3h in a nitrogen sintering atmosphere, then sintered at 650°C for 16h, and cooled to room temperature to obtain Li 2 Ni 0.9 Zn 0.1 O 2 Lithium supplements.

[0037] Example 4 The specific preparation steps are as follows: (1) Use of NiSO 4 6H 2 O and ZnSO 4 6H 2 O Prepare a 2 mol / L mixed salt solution of Ni and Zn according to the predetermined molar ratio of Ni:Zn=0.95:0.05, use NaOH to prepare an alkali solution with a concentration of 4 mol / L, and use concentrated ammonia water to dilute and prepare a complexing agent with a concentration of 1 mol / L; prepare a start-up base solution with a pH of 12 and an ammonia concentration of 2 g / L; Keep the pH and ammonia concentration constant, pump in the mixed salt solution and alkali solution at the same time, and remove the seeds for 10 minutes; reduce the alkali solution flow rate to slowly reduce the pH to 10.8, then keep the pH constant, stop feeding after the particle size of the lithium supplement precursor grows to about 5.0μm; The reaction atmosphere was nitrogen, the reaction temperature was 55°C, and the stirring rate of the reactor was 500 rpm. The materials in the reactor were aged for 3 hours, and then solid-liquid separation, washing, drying, sieving, and demagnetization were performed to obtain Ni 0.95 Zn 0.05 (OH) 2 Lithium supplement additive precursor; (2) Ni 0.95 Zn 0.05 (OH) 2 The lithium supplement additive precursor and lithium hydroxide were mixed evenly according to the (Ni+Zn) / Li molar ratio of 1:1.9, first sintered at 450°C for 3h in a nitrogen sintering atmosphere, then sintered at 650°C for 18h, and cooled to room temperature to obtain Li 2 Ni 0.95 Zn 0.05 O 2 Lithium supplements.

[0038] Comparative Example 1 The specific preparation steps are as follows: Lithium hydroxide, nickel oxide and zinc oxide were mixed evenly according to the molar ratio of Li:Ni:Zn=1.95:0.85:0.15, sintered at 400°C for 4h in a nitrogen sintering atmosphere, then sintered at 700°C for 14h, and cooled to room temperature to obtain Li 2Ni 2 O 2 Lithium supplements.

[0039] Comparative Example 2 The specific preparation steps are as follows: Lithium hydroxide, nickel oxide and zinc oxide were mixed evenly according to the molar ratio of Li:Ni:Zn=2.0:0.85:0.15, sintered at 350°C for 6h in a nitrogen sintering atmosphere, then sintered at 750°C for 12h, and cooled to room temperature to obtain Li 2 Ni 0.85 Zn 0.15 O 2 Lithium supplements.

[0040] Comparative Example 3 The specific preparation steps are as follows: Lithium hydroxide, nickel oxide and zinc oxide were mixed evenly according to the molar ratio of Li:Ni:Zn=2.0:0.9:0.1, sintered at 450°C for 3h in a nitrogen sintering atmosphere, then sintered at 650°C for 16h, and cooled to room temperature to obtain Li 2 Ni 0.9 Zn 0.1 O 2 Lithium supplements.

[0041] Comparative Example 4 The specific preparation steps are as follows: According to the molar ratio of Li:Ni:Zn=2.1:0.95:0.05, lithium hydroxide, nickel oxide and zinc oxide were mixed evenly, sintered at 450°C for 3h in a nitrogen sintering atmosphere, then sintered at 650°C for 18h, and cooled to room temperature to obtain Li 2 Ni 0.95 Zn 0.05 O 2 Lithium supplements.

[0042] Comparative Example 5 The specific preparation steps are as follows: Lithium hydroxide and nickel oxide were mixed evenly according to the molar ratio of Li:Ni=1.95:0.85, sintered at 400°C for 4h in a nitrogen sintering atmosphere, then sintered at 700°C for 14h, and cooled to room temperature to obtain Li 2 Ni 2 O 2 Lithium supplements.

[0043] Test Trial 1. Button battery test The electrochemical properties of the materials prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were tested.

[0044] Test method: The materials prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were mixed with the conductive agent acetylene black and the binder PVDF in a mass ratio of 9:0.5:0.5 in 10 ml of N-methylpyrrolidone, and stirred thoroughly to form a positive electrode slurry (the lithium supplement additive was used as the positive electrode active material in the material buckle test), and then coated on the surface of the aluminum foil by a coating machine, and cut into a suitable size after drying. The lithium sheet was used as the negative electrode, the lithium hexafluorophosphate solution was used as the electrolyte, and the button battery was assembled in an argon-protected glove box using a 2032 button battery shell. Then, the room temperature electrochemical performance test was carried out at 25°C at 2.75-4.3V, and the test results are shown in Table 1.

[0045] Table 1 Electrical performance data of various embodiments and comparative examples

[0046] As can be seen from the above table, by comparing Example 1 with Comparative Example 5, the Li 2 Ni x Zn (1-x) O 2 Compared with single metal Li 2 NiO 2 The lithium supplement has better structural stability. The introduction of zinc doping can inhibit lithium dissolution, reduce residual alkali, and increase the irreversible capacity.

[0047] By comparing Examples 1 to 4 with Comparative Examples 1 to 4, compared with the positive electrode lithium supplement obtained by sintering the traditional oxide, the residual alkali content in the lithium supplement prepared by the present invention is lower, the first effect and irreversible specific capacity are higher, and the charge and discharge specific capacity is basically the same as the comparative example. This shows that the preparation of the lithium supplement additive precursor by coprecipitation can achieve uniform mixing of elements and improve the uniformity of the element distribution of the material; and then by mixing the lithium source for sintering, the generation of impurities in the sintering process is avoided, so the presence of free lithium can be reduced, thereby achieving the effect of reducing residual alkali.

[0048] 2. Material application performance test The lithium supplement materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were mixed with the ternary positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 , acetylene black as a conductive agent, and PVDF as a binder were mixed in a mass ratio of 3:87:5:5 with NMP as a solvent to obtain a positive electrode slurry; then coated on the surface of aluminum foil by a coating machine, dried and cut into a suitable size, and assembled into a button battery in an argon-protected glove box using a lithium sheet as a negative electrode and a lithium hexafluorophosphate solution as an electrolyte using a 2032 button battery shell. Then, the room temperature electrochemical performance test was carried out at 25°C at 2.75-4.3V, and the test results are shown in Table 2.

[0049] Table 2 Electrical performance data of various embodiments and comparative examples

[0050] From the data shown in Table 2, the lithium replenishing material and the positive electrode material are mixed in proportion and made into a battery cell after slurry adjustment. During the first charging process, the lithium replenishing material releases excess lithium, which can replenish the lithium consumed by the formation of the SEI film on the surface of the negative electrode, thereby completing the lithium replenishment and improving the first-cycle discharge capacity of the battery.

[0051] The positive electrode lithium supplement material prepared by Examples 1 to 4 and Comparative Examples 1 to 5 and LiNi0.8Co 0.1 Mn 0.1 O 2 The ternary positive electrode material, conductive agent acetylene black and binder PVDF were mixed in proportion and assembled for a charge-and-discharge test. The first-cycle discharge capacity of the charge-and-discharge test was maintained at a high level.

[0052] By comparing Example 1 with Comparative Example 5, the Li 2 N ix Zn (1-x) O 2 Bimetallic lithium supplements are better than single metal Li prepared by traditional oxide sintering. 2 NiO 2 Lithium supplement has a higher initial effect, because the introduction of zinc doping can inhibit lithium dissolution and reduce residual alkali. Lower residual alkali can improve the stability of positive electrode slurry, reduce the occurrence of battery side reactions, and increase the irreversible capacity of the battery.

[0053] By comparing Examples 1 to 4 with Comparative Examples 1 to 4, compared with the positive electrode lithium replenisher obtained by traditional oxide sintering, the bimetallic lithium replenisher prepared by the present invention is used in buckle battery, and the first cycle coulomb efficiency, the second cycle coulomb efficiency and the 1C cycle 50 cycle capacity retention rate of the battery are better than those prepared by the traditional oxide sintering method. This is because the lithium replenishing additive precursor is prepared by coprecipitation, and then the bimetallic positive electrode lithium replenishing material obtained by mixing the lithium source and sintering has lower residual alkali and better structural uniformity. Higher residual alkali will increase gas production and side reactions, which will increase irreversible capacity loss and deteriorate cycle performance. Lower residual alkali makes the structure uniform, which can reduce metal dissolution and improve cycle performance.

[0054] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A positive electrode lithium supplement additive, whose molecular formula is Li2Ni x Zn (1-x) O2, where 0.8<x<1。 2. The method for preparing the positive electrode lithium supplement additive according to claim 1, comprising the following steps: S1, mixing a soluble metal salt mixed solution, an alkali solution and a complexing agent, and performing a coprecipitation reaction to obtain a precursor metal hydroxide Ni x Zn (1-x) (OH)2; S2, the obtained precursor metal hydroxide Ni x Zn (1-x) (OH)2 is mixed with a lithium source and sintered to obtain the positive electrode lithium supplement additive Li2Ni x Zn (1-x) O2.

3. The preparation method according to claim 2, characterized in that: In step S1, the soluble metal salt is a nickel salt and a zinc salt; The total concentration of metal ions in the soluble metal salt mixed solution is 1-2 mol / L.

4. The preparation method according to claim 2 or 3, characterized in that: In step S1, the alkali is sodium hydroxide and / or potassium hydroxide; The concentration of the alkali solution is 2-4 mol / L.

5. The preparation method according to any one of claims 2 to 4, characterized in that: In step S1, the complexing agent is ammonia water; the concentration of the ammonia water is 1-2 mol / L.

6. The preparation method according to any one of claims 2 to 5, characterized in that: In step S1, the coprecipitation reaction is carried out according to the following operation: Under protective atmosphere, a reaction bottom solution with a pH value of 11-12 and an ammonia concentration of 2-4 g / L was pumped into the reactor, and then a soluble metal salt mixed solution, an alkali solution and a complexing agent were pumped into the reactor at the same time. The reaction was started under the conditions of pH = 11-12, an ammonia concentration of 1.0-2.0 g / L, a temperature of 50-60 ° C, and a stirring intensity of 400-600 rpm. During the reaction, the pH range was controlled between 10.6 and 12, the ammonia concentration was kept unchanged, and the precursor particles grew. When the particle size D 50 When the particle size reaches 3-10 μm, the feeding is stopped, the particles are aged and separated to obtain a lithium supplement additive precursor.

7. The preparation method according to any one of claims 2 to 6, characterized in that: In step S2, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, and lithium oxide; The gas used for sintering is selected from one or more of nitrogen, argon, carbon monoxide and hydrogen; The sintering conditions are: pre-sintering at 350-450°C for 3-5h, and then sintering at 600-700°C for 12-18h.

8. A method for preparing a lithium-ion battery, comprising preparing a positive electrode slurry; The positive electrode slurry is prepared by the following steps: adding the positive electrode lithium supplement additive according to claim 1, the ternary positive electrode material, the conductive agent, and the binder into a solvent to form a positive electrode slurry.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the positive electrode lithium supplement additive to the ternary positive electrode material, the conductive agent, and the binder is x: (90-x): 5: 5, wherein 1≤x≤5.

10. The lithium ion battery obtained by the preparation method according to claim 8 or 9.

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