A positive electrode lithium supplementing material, a preparation method and application thereof

Abstract

The application provides a positive electrode lithium supplementing material and a preparation method and application thereof. The positive electrode lithium supplementing material comprises a substrate, a secondary coating layer coated on the surface of the substrate, and a carbon coating layer on the outermost layer. The substrate comprises a lithium iron oxide containing a doping element. The doping element comprises any one or a combination of at least two of cerium, ruthenium, antimony, zirconium, iridium or niobium. The coating element in the secondary coating layer comprises any one or a combination of at least two of silicon, tantalum, magnesium or strontium. The application simultaneously realizes the doping and coating of the material by using specific doping elements and coating elements, and the outermost surface is a carbon coating layer, so that the residual alkali content of the material is reduced and the conductivity of the material is improved. When the material is used in a battery, the first charge capacity of the battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a positive electrode lithium replenishment material, its preparation method, and its application. Background Technology

[0002] Significant progress has been made in lithium-ion battery research, with improvements in specific capacity, cycle stability, and rate performance. However, many challenges remain. Irreversible capacity loss, in particular, limits the application of many high-energy materials, and most of this loss originates from the lithium ions consumed during the formation of the solid electrolyte membrane during the initial charge.

[0003] During the first charge of a lithium-ion battery, the organic solvents in the electrolyte (such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC)) readily decompose on the surface of the negative electrode after drawing lithium ions from the positive electrode, forming a passivation film called the solid electrolyte interphase (SEI) film. The SEI film insulates against electron passage while allowing lithium ions to pass through; it is an electronic insulator but an excellent ionic conductor, effectively inhibiting further electrolyte decomposition and preventing the formation of a thicker SEI film after the first cycle. The SEI film mainly consists of organic components such as RCOOLi, ROLi, and ROCO2Li, as well as inorganic components such as Li2CO3, Li2O, LiOH, and LiF. The formation of these lithium-containing components is irreversible, thus permanently consuming a portion of the lithium from the positive electrode. + This reduces the coulombic efficiency (ICE) of the first cycle and results in lower energy and capacity density of lithium-ion batteries.

[0004] Therefore, researchers have developed lithium replenishment technology, which adds a new lithium source to the electrode material to compensate for the loss of active lithium caused by the formation of the SEI film during the first cycle. Positive electrode lithium replenishment involves adding lithium replenishing materials as additives during the positive electrode slurry homogenization process. After the cell is manufactured, during the first charge and discharge, the positive electrode lithium replenishing material, due to its high specific capacity and low initial efficiency, releases a large number of lithium ions during normal charging to replenish the lithium ions consumed in the formation of the SEI film on the negative electrode. During discharge, due to its low initial efficiency, it does not accept a large number of lithium ions, thus increasing the battery capacity. Existing positive electrode lithium replenishment additives have high residual alkali values. These residual alkalis can react with the positive electrode binder, polyvinylidene fluoride (PVDF), easily causing chemical gelation during slurry stirring, increasing slurry viscosity, and affecting electrode processing. Furthermore, these residual alkalis may react with the electrolyte at high temperatures, generating carbon dioxide or other solid substances, leading to increased battery gas production or increased battery impedance, ultimately causing a decline in battery performance.

[0005] CN107863567A describes the use of Li2O powder doped with conductive metals to create a positive electrode lithium replenishment material, which can achieve lithium replenishment and thus improve battery capacity. However, in actual use, this positive electrode lithium replenishment material is prone to problems. Due to the reaction between Li2O (which reacts with water to produce the strong alkali LiOH) and trace amounts of water in N-methylpyrrolidone (NMP), PVDF decomposition and deactivation can easily occur, leading to agglomeration in the positive electrode slurry and making coating impossible. Furthermore, even when coated in a very harsh anhydrous environment, the insulator Li2O will not decompose completely during the first charge lithium replenishment process, and gas will still be generated during battery use, causing battery swelling and rupture, resulting in safety issues.

[0006] Therefore, how to reduce the residual alkali in the positive electrode lithium replenishment material and improve the conductivity of the material is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a positive electrode lithium replenishment material, its preparation method, and its application. This invention achieves both doping and coating of the material simultaneously by employing specific doping and coating elements, with the outermost surface being a carbon coating layer. This reduces the residual alkali content and improves the material's conductivity, thereby enhancing the battery's initial charge capacity when used in a battery.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a positive electrode lithium replenishment material, the positive electrode lithium replenishment material comprising a substrate, a sub-coating layer covering the surface of the substrate, and an outermost carbon coating layer, wherein the substrate comprises lithium iron oxide containing doped elements; the doped elements comprise any one or a combination of at least two of cerium, ruthenium, antimony, zirconium, iridium, or niobium; and the coating elements in the sub-coating layer comprise any one or a combination of at least two of silicon, tantalum, magnesium, or strontium.

[0010] This invention employs specific doping and coating elements, which work synergistically with the coating elements in the coating layer. The types of elements cannot be changed. In addition, the outermost carbon coating layer reduces the residual alkali content of the material and improves its conductivity. When used in batteries, this invention increases the initial charging capacity of the battery.

[0011] Preferably, the compaction density F, D10 and D90 of the positive electrode lithium replenishment material satisfy the following: 1.0≤F / (D10*D90)≤1.5, where the compaction density F is the compaction density under a pressure of 2t, such as 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0012] In this invention, a relationship is established between the powder compaction density F, D10, and D90 of the positive electrode lithium replenishment material. By adjusting these parameters, the viscosity of the slurry can be adjusted during homogenization, which is beneficial for subsequent processing. If the relationship is less than 1, it indicates that the particle size is small and the powder compaction is low, which is not conducive to viscosity adjustment during homogenization. The large viscosity rebound will lead to failure to coat the material. If the relationship is greater than 1.5, it indicates that the particle size is large and the powder compaction is relatively high, which will result in a low battery capacity that cannot meet the usage requirements.

[0013] In a second aspect, the present invention provides a method for preparing a positive electrode lithium replenishment material as described in the first aspect, the preparation method comprising the following steps:

[0014] (1) Mix lithium source, iron source and dopant, and sinter to obtain matrix material;

[0015] (2) The matrix material and the coating agent are mixed once and sintered once. The product after the first sintering is mixed with the carbon source a second time and sintered a second time to obtain the positive electrode lithium replenishment material.

[0016] The dopant includes any one or a combination of at least two of cerium source, ruthenium source, antimony source, zirconium source, iridium source or niobium source; the coating element in the coating agent includes any one or a combination of at least two of silicon source, tantalum source, magnesium source or strontium source.

[0017] The preparation method provided by this invention is simple and feasible. The dopant is directly added during the preparation of the matrix material to achieve bulk doping of the dopant element. Then, the coating agent is applied, and finally, the carbon layer is applied to obtain a positive electrode lithium replenishment material with low residual alkali and good conductivity.

[0018] In this invention, no special limitations are placed on the raw materials of lithium, iron, and carbon sources, nor on the raw materials of cerium, ruthenium, antimony, zirconium, iridium, and niobium sources in the dopants, or silicon, tantalum, and magnesium sources in the coating agents. Any material that can be used for sintering and reaction is applicable to this invention, for example:

[0019] Conventional lithium sources in this field include lithium hydroxide monohydrate, anhydrous lithium hydroxide, lithium chloride, lithium bromide, and lithium carbonate.

[0020] Common iron sources in this field include ferric oxide, ferric chloride, ferric nitrate, ferric sulfate, and ferric bromide.

[0021] Common zirconium sources in this field include zirconium oxide, zirconium sulfide, zirconium bicarbonate, zirconium silicate, zirconium boride, zirconium tungstate, zirconium dichromate, zirconium hydroxide, zirconium nitrate, zirconium phosphate, or zirconium chloride.

[0022] Common cerium sources in this field include cerium oxide, cerium carbonate, cerium sulfate, and cerium phosphate.

[0023] Common ruthenium sources in this field include ruthenium acetate, ammonium ruthenium chloride, ammonium ruthenium chloride, ruthenium trichloride, ruthenium oxide, ruthenium iodide, potassium ruthenium chloride, etc.

[0024] Common niobium sources in this field include niobium pentoxide, lithium niobate, niobium ethanol, niobium pentafluoride, and niobium pentachloride.

[0025] Conventional antimony sources in this field include antimony trioxide, antimony halides (F / Cl / Br), and triphenyl antimony.

[0026] Common iridium sources in the art, such as iridium trioxide, iridium dioxide, iridium hydroxide, iridium sulfide, iridium chloride, and hexachlorodiaminoiridium ((NH4)2IrCl6), can all be used in this invention.

[0027] Conventional silicon sources in this field include silicon dioxide, silicic acid, silicon fluoride, or silicon chloride.

[0028] Conventional tantalum sources in this field include tantalum pentoxide, tantalum pentachloride, tantalum pentanitride, tantalic acid, potassium fluorotantalate, or tantalum sulfide.

[0029] Common magnesium sources in the art include magnesium oxalate, magnesium acetate, magnesium oxide, magnesium carbonate, or magnesium hydroxide.

[0030] Common strontium sources in the art include strontium oxalate, strontium acetate, strontium oxide, strontium carbonate, strontium nitrate, or strontium titanate.

[0031] Conventional carbon sources in the art include polyethylene glycol, polypropylene, phenolic resins, epoxy resins, polyimide, polycarbonate, or glucose.

[0032] Preferably, in step (1), the mass ratio of the dopant element in the dopant, the iron in the iron source, and the lithium in the lithium source is (0.0005~0.01):1:(5~6), for example, 0.0005:15, 0.0005:1:5.5, 0.0005:1:6, 0.001:1:5, 0.005:1:5, 0.01:1:5, 0.01:1:5.5, or 0.01:1:6, etc.

[0033] Preferably, the mixing in step (1) includes liquid phase mixing.

[0034] In this invention, liquid-phase mixing can better achieve uniform mixing of raw materials, resulting in materials with uniform composition.

[0035] Preferably, the liquid phase is dynamically dried after mixing.

[0036] In this invention, dynamic drying is more conducive to material drying, avoids the caking phenomenon that occurs with static drying, and thus reduces the need for post-processing.

[0037] Preferably, the temperature for dynamic drying is 100-150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C.

[0038] Preferably, the pressure of the dynamic drying is -0.04 to -0.2 MPa, such as -0.04 MPa, -0.05 MPa, -0.1 MPa, -0.13 MPa, -0.15 MPa, -0.18 MPa or -0.2 MPa.

[0039] Preferably, the dynamic drying time is 1 to 10 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0040] Preferably, the sintering temperature in step (1) is 600 to 900°C, for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C.

[0041] Preferably, the sintering time in step (1) is 10 to 20 hours, such as 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, or 20 hours.

[0042] Preferably, the amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the positive electrode lithium replenishment material satisfy 2≤Ex-Li / (N+M)≤50, for example, 2, 3, 5, 8, 10, 12, 13, 15, 18, 20, 23, 24, 25, 28, 30, 33, 35, 36, 38, 40, 43, 45, 48, or 50.

[0043] In this invention, the residual alkali content of the cathode lithium replenishment material is controlled by adjusting the amount of dopant and coating agent added. When the residual alkali content is not within the range of 2 to 50, or when it is not within the range of 2 to 50, the purpose of reducing residual alkali cannot be achieved. At the same time, adjusting the relationship formula cannot accurately reflect the relationship between the residual alkali content and the amount of dopant and coating agent added.

[0044] Preferably, the mass ratio of the coating agent to the matrix material is (0.0005 to 0.01):1, for example, 0.0005:1, 0.0008:1, 0.001:1, 0.005:1, 0.008:1 or 0.01:1, etc.

[0045] Preferably, the rotation speed of the first mixing in step (2) is 100 to 300 rpm, such as 100 rpm, 150 rpm, 200 rpm, 250 rpm or 300 rpm.

[0046] Preferably, the mixing time in step (2) is 1 to 5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0047] Preferably, the sintering time in step (2) is 2 to 10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0048] Preferably, the temperature of the first sintering in step (2) is 500 to 700°C, for example, 500°C, 550°C, 600°C, 650°C or 700°C.

[0049] Preferably, in step (2), the mass ratio of the product after one sintering to the carbon source is 1:(2~10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, etc.

[0050] Preferably, the temperature of the secondary sintering in step (2) is 200 to 300°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C.

[0051] As a preferred technical solution, the preparation method includes the following steps:

[0052] (1) The lithium source, iron source and dopant are mixed in liquid phase with the mass ratio of dopant element in the dopant, iron in the iron source and lithium in the lithium source being (0.0005~0.01):1:(5~6), dynamically dried at 100~150℃ and -0.04~-0.2Mpa for 1~10h, and then sintered at 600~900℃ for 10~20h to obtain the matrix material;

[0053] (2) The matrix material and the coating agent are mixed once at 100-300 rpm for 1-5 h at a mass ratio of 1:(0.0005-0.01), and sintered once at 500-700℃. The product after the first sintering is mixed with the carbon source at a mass ratio of 1:(1-10), and sintered again at 200-300℃ to obtain the positive electrode lithium replenishment material.

[0054] The dopant includes any one or a combination of at least two of cerium, ruthenium, antimony, zirconium, iridium, or niobium sources; the coating element in the coating agent includes any one or a combination of at least two of silicon, tantalum, magnesium, or strontium sources; the amount of dopant added (N), the amount of coating agent added (M), and the total alkali content (Ex-Li) of the positive electrode lithium replenishment material satisfy 2 ≤ Ex-Li / (N+M) ≤ 50.

[0055] Thirdly, the present invention also provides a lithium-ion battery, the lithium-ion battery comprising the positive electrode lithium replenishment material as described in the first aspect.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] This invention employs specific doping and coating elements, which work synergistically with the coating elements in the coating layer. The types of these elements cannot be changed. Combined with the outermost carbon coating layer, this reduces the residual alkali content and improves the material's conductivity. When used in batteries, this increases the initial charging capacity. Furthermore, the preparation method is simple and suitable for large-scale production. When the positive electrode lithium replenishment material provided by this invention is added to the battery's positive electrode, and the powder compaction density F, D10, and D90 of the positive electrode lithium replenishment material satisfy the following condition: 1.0 ≤ F / (D10*D90) ≤ 1.5, and the amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the positive electrode lithium replenishment material satisfy the condition: 2 ≤ Ex-Li / (N+M) ≤ 50, the charging capacity at 0.1C can be increased by more than 9.06% compared to a control group (without the positive electrode lithium replenishment material of this invention in the positive electrode). Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] Example 1

[0060] This embodiment provides a positive electrode lithium replenishment material, which includes a substrate, a secondary coating layer covering the surface of the substrate, and an outermost carbon coating layer. The substrate includes lithium iron oxide containing cerium dopant (the undoped chemical formula is Li5FeO4); the coating element in the secondary coating layer is tantalum.

[0061] The preparation method of the positive electrode lithium replenishment material is as follows:

[0062] (2) Cerium oxide, ferric chloride and lithium hydroxide were weighed and added to 1.5L of organic solvent ethanol in a mass ratio of 0.002:1.0:5.5. The mixture was stirred for 2 hours, filtered and washed, and then dynamically dried in a double cone dryer (temperature: 130℃, negative pressure: -0.04MPa, drying time: 5h). The mixture was then sintered at a sintering temperature of 700℃ for 15 hours under an argon atmosphere to obtain the matrix material.

[0063] (2) Weigh tantalum pentoxide and matrix material at a mass ratio of 0.0035:1.0 and put them into a planetary ball mill for mixing (mixing conditions: speed 200 rpm, mixing time 3 h). Place the mixture in a high temperature atmosphere furnace and sinter at 600°C for 6 h under argon atmosphere protection to obtain a product sintered once.

[0064] (3) The product of the first sintering and polyethylene glycol (the mass ratio of the product of the first sintering to polyethylene glycol is 1:3) are put into a high-speed mixer and mixed evenly. The mixture is then calcined at 250°C under an argon atmosphere to obtain the positive electrode lithium replenishment material.

[0065] Examples 2-5

[0066] In Examples 2-5, the amounts of dopant and coating agent were adjusted so that the material's F / (D10*D90) (powder compaction density F, D10, and D90) and Ex-Li / (N+M) (the amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the cathode lithium replenishment material) were different.

[0067] The remaining preparation methods and parameters are consistent with those in Example 1.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is that this comparative example does not involve doping or coating Li5FeO4.

[0070] The remaining preparation methods and parameters are consistent with those in Example 1.

[0071] The F / (D10*D90) and Ex-Li / (N+M) and the total alkali content of the materials in Examples 1-5 and Comparative Example 1 are shown in Table 1.

[0072] Table 1

[0073] Example 1 1.1 12 25500 Example 2 1.2 24 18400 Example 3 1.3 36 13720 Example 4 1.5 50 20500 Example 5 2 60 40080 Comparative Example 1 0.5 - 41300

[0074] Coin cells were prepared using the positive electrode lithium replenishment materials provided in Examples 1-5 and Comparative Example 1. The positive electrode lithium replenishment material, lithium iron phosphate positive electrode material, SP, PVDF adhesive, and NMP were weighed and homogenized, coated, and baked. The dried electrode sheets were then rolled, cut, and assembled into 2032 coin cells. The ratio of lithium iron phosphate positive electrode material to SP to PVDF powder was 90:5:5 (mass ratio), and the positive electrode lithium replenishment material accounted for 2% of the lithium iron phosphate positive electrode material. The electrochemical performance results are those after application to the positive electrode material (no positive electrode lithium replenishment material was added in the control group).

[0075] The test conditions were: a 0.1C first-cycle charge-discharge test was performed at 3–4.3V, and the results are shown in Table 2.

[0076] Table 2

[0077]

[0078] Combining the data from Tables 1 and 2, we can see that:

[0079] The data from Examples 1-5 show that the cathode lithium-supplementing material with a lithium content of 1.0 ≤ F / (D10*D90) ≤ 1.5 and 2 ≤ Ex-Li / (N+M) ≤ 50 exhibits better lithium-supplementing performance. However, exceeding these ranges leads to excessively large or small particle sizes, resulting in over- or under-compacted powder, which negatively impacts homogenization, slurry viscosity, and lithium-supplementing effect. Carbon coating significantly improves the air stability and conductivity of the lithium-supplementing material.

[0080] As can be seen from the data results of Examples 1-4 and Comparative Example 1, the positive electrode lithium replenishment material provided by the present invention has lower residual alkali and higher first-week charging capacity compared with pure lithium replenishment material without doping and coating.

[0081] In summary, this invention employs specific doping and coating elements, which work synergistically with each other in the coating layer. The types of these elements cannot be changed. Combined with the outermost carbon coating layer, this reduces the residual alkali content and improves the material's conductivity. When used in batteries, this increases the initial charging capacity. Furthermore, the preparation method is simple and suitable for large-scale production. When the positive electrode lithium replenishment material provided by this invention is added to the battery's positive electrode, and the powder compaction density F, D10, and D90 of the positive electrode lithium replenishment material satisfy the following condition: 1.0 ≤ F / (D10*D90) ≤ 1.5, and the amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the positive electrode lithium replenishment material satisfy the condition: 2 ≤ Ex-Li / (N+M) ≤ 50, the charging capacity at 0.1C can be increased by more than 9.06% compared to the control group (without the positive electrode lithium replenishment material of this invention in the positive electrode).

[0082] The applicant declares that the specific implementation of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A cathode lithium replenishment material, characterized in that, The positive electrode lithium replenishment material includes a substrate, a secondary coating layer covering the surface of the substrate, and an outermost carbon coating layer. The substrate includes lithium iron oxide containing doped elements. The doped elements include any one or a combination of at least two of cerium, ruthenium, antimony, iridium, or niobium. The coating elements in the secondary coating layer include any one or a combination of at least two of silicon, tantalum, magnesium, or strontium. The compaction densities F, D10, and D90 of the positive electrode lithium replenishment material satisfy the following condition: 1.0 ≤ F / (D10*D90) ≤ 1.5, where the compaction density F is the compaction density under a pressure of 2t. The positive electrode lithium replenishment material is prepared by the following method, including: (1) The lithium source, iron source and dopant are mixed and sintered to obtain the matrix material; (2) The matrix material and the coating agent are mixed once and sintered once. The product after the first sintering is mixed with the carbon source a second time and sintered a second time to obtain the positive electrode lithium replenishment material. The dopant includes any one or a combination of at least two of cerium, ruthenium, antimony, iridium, or niobium sources; the coating element in the coating agent includes any one or a combination of at least two of silicon, tantalum, magnesium, or strontium sources. The amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the cathode lithium replenishment material satisfy the relationship 2≤Ex-Li / (N+M)≤50; In step (1), the mass ratio of the dopant element in the dopant, the iron in the iron source, and the lithium in the lithium source is (0.0005~0.01):1:(5~6); In step (2), the mass ratio of the coating agent to the matrix material is (0.0005~0.01):

1.

2. A method for preparing the positive electrode lithium replenishment material as described in claim 1, characterized in that, The preparation method includes the following steps: (1) The lithium source, iron source and dopant are mixed and sintered to obtain the matrix material; (2) The matrix material and the coating agent are mixed once and sintered once. The product after the first sintering is mixed with the carbon source a second time and sintered a second time to obtain the positive electrode lithium replenishment material. The dopant includes any one or a combination of at least two of cerium, ruthenium, antimony, iridium, or niobium sources; the coating element in the coating agent includes any one or a combination of at least two of silicon, tantalum, magnesium, or strontium sources. The amount of dopant N, the amount of coating agent M, and the total alkali content Ex-Li of the cathode lithium replenishment material satisfy the relationship 2≤Ex-Li / (N+M)≤50; In step (1), the mass ratio of the dopant element in the dopant, the iron in the iron source, and the lithium in the lithium source is (0.0005~0.01):1:(5~6); In step (2), the mass ratio of the coating agent to the matrix material is (0.0005~0.01):

1.

3. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The mixing in step (1) includes liquid phase mixing.

4. The method for preparing the positive electrode lithium replenishment material according to claim 3, characterized in that, The liquid phases are mixed and then dynamically dried.

5. The method for preparing the positive electrode lithium replenishment material according to claim 4, characterized in that, The temperature for dynamic drying is 100~150℃.

6. The method for preparing the positive electrode lithium replenishment material according to claim 4, characterized in that, The pressure for dynamic drying is -0.04 to -0.2 MPa.

7. The method for preparing the positive electrode lithium replenishment material according to claim 5, characterized in that, The dynamic drying time is 1 to 10 hours.

8. The method for preparing the positive electrode lithium replenishment material according to claim 2 or the method thereof, characterized in that, The sintering temperature in step (1) is 600~900℃.

9. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The sintering time in step (1) is 10~20h.

10. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The rotation speed for the first mixing step (2) is 100~300 rpm.

11. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The mixing time in step (2) is 1 to 5 hours.

12. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The sintering time in step (2) is 2 to 10 hours.

13. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The temperature for the first sintering in step (2) is 500~700℃.

14. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, In step (2), the mass ratio of the product after one sintering to the carbon source is 1:(2~10).

15. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The temperature of the secondary sintering in step (2) is 200~300℃.

16. The method for preparing the positive electrode lithium replenishment material according to claim 2, characterized in that, The preparation method includes the following steps: (1) The lithium source, iron source and dopant are mixed in liquid phase with the mass ratio of dopant element in the dopant, iron in the iron source and lithium in the lithium source being (0.0005~0.01):1:(5~6), dynamically dried at 100~150℃ and -0.04~-0.2Mpa for 1~10h, and then sintered at 600~900℃ for 10~20h to obtain the matrix material; (2) The matrix material and the coating agent are mixed once at 100-300 rpm for 1-5 h at a mass ratio of 1:(0.0005~0.01), and sintered once at 500-700℃. The product after the first sintering is mixed with the carbon source at a mass ratio of 1:(2~10), and sintered again at 200-300℃ to obtain the positive electrode lithium replenishment material. The dopant includes any one or a combination of at least two of cerium, ruthenium, antimony, iridium, or niobium sources; the coating element in the coating agent includes any one or a combination of at least two of silicon, tantalum, magnesium, or strontium sources; the amount of dopant added (N), the amount of coating agent added (M), and the total alkali content (Ex-Li) of the positive electrode lithium replenishment material satisfy 2 ≤ Ex-Li / (N+M) ≤ 50.

17. A lithium-ion battery, characterized in that, The lithium-ion battery includes the positive electrode lithium replenishment material as described in claim 1.

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