Lithium ion positive electrode lithium supplementing material and preparation method and application thereof

Abstract

The invention discloses a lithium ion positive electrode lithium supplementing material and a preparation method and application thereof, and relates to the technical field of lithium batteries. By introducing Li2Mo3S13 into the lithium ion positive electrode lithium supplementing material, the utilization rate of lithium ions is improved, and meanwhile, the amount of residual alkali can be reduced by matching with a main body material of the lithium ion positive electrode lithium supplementing material; li2Mo3S13 has relatively good oxidation resistance, so that the stability of the lithium supplementing agent is improved, the lithium supplementing agent is not easy to react with water, and gel is not easy to generate. In addition, the utilization rate of lithium ions is increased, so that the gram volume of the lithium supplementing agent is also increased; and the catalytic action of the [Mo3S13] molecular cluster also enables the EIS of the assembled battery to be reduced, and the power performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and more particularly, to a lithium-ion cathode lithium supplement material, a preparation method thereof, and an application thereof. Background Art

[0002] During the first charge and discharge process of a lithium-ion battery, a solid electrolyte interface film is formed on the surface of the negative electrode, causing irreversible loss of active lithium, which in turn leads to a decrease in the capacity of the electrode material and a decrease in energy density, severely limiting the widespread application of lithium-ion batteries. By adding a lithium supplement material to the positive electrode material, the loss of active lithium during the first charging process of the lithium-ion battery can be compensated, effectively improving the energy density of the lithium-ion battery.

[0003] In the pre-lithiation technology, materials based on the anion oxidation mechanism, such as Li2S, Li3N, Li2O, Li5FeO4, Li2NiO2, Li6CoO4, Li2CO3, etc., have been widely studied. However, the synthesis of these materials is extremely sensitive to moisture. After reacting with water, it is easy to gel the positive electrode slurry of lithium ions. Even when the water content is very low, it will cause an increase in the resistance of the electrode sheet. In addition, these lithium supplement agents all contain a certain amount of residual alkali, which greatly reduces the utilization rate of lithium ions. All of the above reasons limit the further popularization and application of lithium supplement materials in the industrialization of lithium-ion batteries.

[0004] Therefore, there is an urgent need to develop a lithium supplement agent that can increase the utilization rate of lithium ions, reduce residual alkali, and improve the stability of the lithium supplement agent at the same time.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a lithium-ion cathode lithium supplement material, a preparation method thereof, and an application thereof, aiming to reduce residual alkali while increasing the utilization rate of lithium ions and improving the stability of the lithium supplement agent.

[0007] The present invention is implemented as follows:

[0008] In a first aspect, the present invention provides a lithium-ion cathode lithium supplement material, which includes a main material and Li2Mo3S 13 .

[0009] In an alternative embodiment, in the lithium-ion cathode lithium supplement material, the mass fraction of Li2Mo3S 13 is 0.5%-2%;

[0010] and / or, the main material of the lithium-ion cathode lithium supplement material is selected from at least one of lithium ferrite, lithium nickelate, and ternary cathode materials.

[0011] Second aspect, the present invention provides a method for preparing the lithium-ion cathode lithium supplementing material of the foregoing embodiments, including: providing (NH4)2Mo3S 13 molecular cluster;

[0012] Adding (NH4)2Mo3S 13 molecular cluster during the sintering stage of the host material preparation process to generate the lithium conductor Li2Mo3S 13 .

[0013] In an optional embodiment, the preparation process of the (NH4)2Mo3S 13 molecular cluster includes: mixing an ammonium molybdate aqueous solution and an ammonium polysulfide solution, reacting at 80°C - 95°C for 1h - 3h, allowing to stand and separating the solid material, and then washing and drying.

[0014] In an optional embodiment, the concentration of the ammonium molybdate aqueous solution is 20g / L - 50g / L;

[0015] and / or, the drying temperature is 120°C - 140°C.

[0016] In an optional embodiment, the host material of the lithium-ion cathode lithium supplementing material is lithium ferrite, and the preparation process includes:

[0017] Mixing lithium ferrite and (NH4)2Mo3S 13 molecular cluster and pulverizing, and then holding at 500°C - 700°C for 10h - 15h;

[0018] Preferably, sintering is carried out under a methane protective gas.

[0019] In an optional embodiment, the host material of the lithium-ion cathode lithium supplementing material is lithium nickelate, and the preparation process includes:

[0020] Mixing nickel oxide, a lithium source and (NH4)2Mo3S 13 molecular cluster, first holding at 250°C - 350°C for 1h - 3h, and then holding at 500°C - 700°C for 10h - 15h;

[0021] Preferably, sintering is carried out under a methane protective gas.

[0022] In an optional embodiment, the lithium source is selected from at least one of lithium oxide, lithium nitride and lithium sulfide.

[0023] Third aspect, the present invention provides a positive electrode sheet, including the lithium-ion cathode lithium supplementing material of any one of the foregoing embodiments or the lithium-ion cathode lithium supplementing material prepared by the preparation method of any one of the foregoing embodiments.

[0024] Fourthly, the present invention provides a lithium battery, including the positive electrode sheet of the foregoing embodiment.

[0025] The present invention has the following beneficial effects: by introducing Li2Mo3S into the lithium-ion positive electrode lithium supplement material, the utilization rate of lithium ions is improved, and at the same time, the main material of the lithium-ion positive electrode lithium supplement material can reduce the residual alkali amount; Li2Mo3S 13 , itself has good oxidation resistance, improves the stability of the lithium supplement agent, makes it not easy to react with water and not easy to gel. In addition, due to the improvement of the lithium ion utilization rate, the specific capacity of the lithium supplement agent is also increased; [Mo3S 13 The catalytic effect of the molecular cluster also reduces the EIS of the assembled battery and improves the power performance. 13 BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0027] Figure 1 For the experimental values and XRD crystal simulation values of the (NH4)2Mo3S 13 molecular cluster;

[0028] Figure 2 For the scanning electron microscope images of the cross-sections of the lithium iron phosphate cores of the electrode sheets made of fresh materials in Example 1 and Comparative Example 1 and the electrode sheets placed in 30% air for 24 hours;

[0029] Figure 3 For the scanning electron microscope images of the cross-sections of the lithium iron phosphate cores of the electrode sheets made of fresh materials in Example 2 and Comparative Example 2 and the electrode sheets placed in 30% air for 24 hours. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0031] The embodiments of the present invention provide a lithium-ion positive electrode lithium supplement material, which contains Li2Mo3S 13 .

[0032] It should be noted that the lithium-ion cathode lithium supplement material provided by the embodiment of the present invention contains the lithium conductor Li2Mo3S 13 , which can be generated during the sintering process, improve the lithium-ion utilization rate, and reduce the residual alkali content. Li2Mo3S 13 itself has good oxidation resistance, improves the stability of the lithium supplement agent, makes it not easy to react with water, and not easy to gel. Due to the improvement of the lithium-ion utilization rate, the specific capacity of the lithium supplement agent is also improved; [Mo3S 13 The catalytic effect of the molecular cluster also reduces the EIS of the assembled battery, improving the power performance.

[0033] In some embodiments, in the lithium-ion cathode lithium supplement material, the mass fraction of Li2Mo3S 13 is 0.5%-2%, such as 0.5%, 1.0%, 1.5%, 2.0%, etc. The mass fraction of Li2Mo3S 13 is preferably within the above range, and within this range, it is beneficial to further improve the electrochemical performance of the cathode material.

[0034] In some embodiments, the main material of the lithium-ion cathode lithium supplement material is selected from at least one of lithium ferrite, lithium nickelate, and ternary cathode materials, and the type of the main material can be any one or several of the above. Combining with the subsequent preparation method, it can be seen that (NH4)2Mo3S 13 molecular clusters are introduced in the sintering stage to consume the residual alkali and improve the utilization rate of lithium ions. Therefore, cathode materials with residual alkali content available in the sintering stage are all suitable for the preparation method provided by the embodiment of the present invention, and a lithium-ion cathode lithium supplement material containing Li2Mo3S 13 is prepared.

[0035] The embodiment of the present invention also provides a preparation method of a lithium-ion cathode lithium supplement material, and the steps are as follows:

[0036] S1. Provide (NH4)2Mo3S 13 molecular clusters

[0037] (NH4)2Mo3S 13 The preparation process of the molecular cluster includes: mixing an ammonium molybdate aqueous solution and an ammonium polysulfide solution, reacting at 80°C - 95°C for 1h - 3h, standing to separate the solid material, and then washing and drying to obtain a red-brown solid product (NH4)2Mo3S 13 .

[0038] Specifically, the reaction temperature can be 80°C, 83°C, 85°C, 88°C, 90°C, 93°C, 95°C, etc., and the reaction time can be 1.0 h, 1.5 h, 2.0 h, 2.5 h, 3.0 h, etc. The washing method is not limited, and solvents such as ethanol, water, and carbon disulfide can be used for washing and suction filtration. The ammonium polysulfide solution is a commercially available raw material, such as it can be purchased from Xiya Chemical Technology Co., Ltd., CAS No.: 9080-17-5, containing 8% NH₃, 22% S, and 30% (NH₄)₂S₃.

[0039] In some embodiments, the concentration of the ammonium molybdate aqueous solution is 20 g / L - 50 g / L, such as it can be 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, etc. Drying can be carried out by vacuum drying, and the drying temperature is 120°C - 140°C, such as it can be 120°C, 125°C, 130°C, 135°C, 140°C, etc.

[0040] S2, sintering

[0041] Add (NH₄)₂Mo₃S 13 molecular clusters during the sintering stage of the main material preparation process, and use the residual alkali to generate the lithium conductor Li₂Mo₃S 13 . The specific sintering process varies according to the different main materials of the lithium-ion cathode lithium supplementing material, but the sintering temperature should not be too high (generally not higher than 900°C), otherwise it will affect the crystal form of Li₂Mo₃S 13 and cause the inability to generate Li₂Mo₃S 13 .

[0042] In some embodiments, the main material of the lithium-ion cathode lithium supplementing material is lithium ferrite, and the preparation process includes: mixing and pulverizing lithium ferrite and (NH₄)₂Mo₃S 13 molecular clusters, then holding at 500°C - 700°C for 10 h - 15 h, and then self-cooling to room temperature. After sintering, (NH₄)₂Mo₃S 13 is converted to Li₂Mo₃S 13 . The sintering atmosphere is not limited, such as it can be a methane protective gas.

[0043] Specifically, lithium ferrite can be a commercially available material, or it can be prepared using lithium hydroxide and iron oxide. Sintering lithium hydroxide and iron oxide under an inert gas, the sintering temperature is 700°C - 900°C, and the sintering time can be 10 h - 20 h. The sintering temperature can be 500°C, 550°C, 600°C, 650°C, 700°C, etc., and the holding time can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, etc. The mixing and pulverizing method is not limited, such as it can adopt the grinding method to achieve the purpose of uniform mixing.

[0044] In another embodiment, the main material of the lithium-ion cathode lithium supplementing material is lithium nickelate, and the preparation process includes: mixing nickel oxide, a lithium source and (NH4)2Mo3S 13 molecular clusters, first heat-insulating at 250°C - 350°C for 1h - 3h, and then heat-insulating at 500°C - 700°C for 10h - 15h. Through a two-step sintering process, a lithium nickelate cathode material (Li2NiO2) with excellent electrochemical performance is prepared, and at the same time, (NH4)2Mo3S 13 is converted into Li2Mo3S 13 , and the equation is as follows:

[0045] (NH4)2Mo3S 13 +NiO+Li2O→Li2Mo3S 13 +Li2NiO2.

[0046] Specifically, the sintering temperature in the first stage can be 250°C, 280°C, 300°C, 330°C, 350°C, etc., and the heat-insulating time can be 1h, 2h, 3h, etc.; the sintering temperature in the second stage can be 500°C, 550°C, 600°C, 650°C, 700°C, etc., and the heat-insulating time can be 10h, 11h, 12h, 13h, 14h, 15h, etc. The sintering atmosphere is not limited, such as it can be a methane protective gas.

[0047] Furthermore, the lithium source is selected from at least one of lithium oxide, lithium nitride and lithium sulfide, and the lithium source can be any one or several of the above.

[0048] The embodiment of the present invention also provides a positive electrode sheet, which includes the lithium-ion cathode lithium supplementing material provided by the embodiment of the present invention. By introducing the lithium conductor Li2Mo3S 13 , it is beneficial to improve the capacity and power performance.

[0049] The embodiment of the present invention also provides a lithium battery, which includes the positive electrode sheet provided by the embodiment of the present invention, and may also include a negative electrode sheet, an electrolyte, a separator, etc. Since the improvement of the positive electrode material is beneficial to improving the electrochemical performance of the lithium battery.

[0050] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0051] Example 1

[0052] The present embodiment provides a preparation method of a lithium-ion cathode lithium supplementing material, and the steps are as follows:

[0053] (1) Dissolve 18 g of ammonium molybdate in 500 mL of deionized water in a glove box, add 600 mL of ammonium polysulfide solution (containing approximately 8% NH₃, 22% S, 30% (NH₄)₂S₃), stir and heat at 90 °C for 2 hours, and then let it stand. Wash by suction filtration with ethanol to obtain a red-brown solid product (NH₄)₂Mo₃S 13 , and vacuum dry it at 130 °C for 6 h.

[0054] (2) Mix 42 g of lithium source LiOH and 160 g of transition metal source Fe₂O₃ (molar ratio 1.75:1) evenly to obtain a mixture. Place the mixture under an inert atmosphere (nitrogen, the same below), sinter at 800 °C for 15 h and crush to obtain the core Li₅FeO₄.

[0055] (3) Grind 1 g of the red-brown solid product (NH₄)₂Mo₃S 13 and 99 g of Li₅FeO₄ into powder and mix evenly. Put the powder after secondary mixing into a crucible, place it in a muffle furnace, and under a methane protection atmosphere, heat it to 600 °C at a heating rate of 5 °C / min, keep it warm for 12 hours, and then cool it naturally to room temperature. After sintering, (NH₄)₂Mo₃S 13 is converted to Li₂Mo₃S 13 .

[0056] (4) Take out the sintered powder, crush it with a ball mill, and pass it through a 200-mesh sieve to obtain a powder with a uniform particle size distribution.

[0057] Note: In this example, the mass ratio of Li₂Mo₃S 13 in the lithium-ion cathode lithium supplementing material product is 1%.

[0058] Example 2

[0059] This example provides a preparation method of a lithium-ion cathode lithium supplementing material, and the steps are as follows:

[0060] (1) The same as step (1) of Example 1.

[0061] (2) Mix nickel sulfate and sodium hydroxide in a molar ratio of 1:0.01 and add them to deionized water to prepare an aqueous solution with a solid content of 20%. At the same time, add them to a reaction kettle for hydrothermal precipitation reaction, then filter, wash, dry at 150 °C, and sinter at 750 °C for 6 h to obtain NiO material.

[0062] (3) The NiO, lithium oxide prepared in step (2) and the (NH₄)₂Mo₃S prepared in step (1) 13 , according to the element ingredient molar ratio of 1:1:0.01 (NiO, lithium oxide and (NH₄)₂Mo₃S 13Weigh them according to the molar ratio of 1:1:0.001, and then put them into a high-energy ball mill. Grind at a rotation speed of 400 rpm for 50 minutes to obtain a mixture.

[0063] (4) Load the mixture obtained in step (3) into a crucible, and heat it to 300 °C at a heating rate of 2 °C / min in a sintering furnace under a methane protection atmosphere, hold for 2 hours, continue to heat at a heating rate of 2 °C / min, heat to 600 °C, hold for 12 hours, then cool to room temperature at a rate of 2 °C / min, and then perform air pulverization to obtain the lithium-rich lithium nickelate material Li2NiO2. After sintering, (NH4)2Mo3S 13 is converted to Li2Mo3S 13 .

[0064] Example 3

[0065] The difference from Example 1 is only that: the mass of the red-brown solid product (NH4)2Mo3S in step (3) 13 is 2 g, and the mass of Li5FeO4 is 98 g. In this example, the mass proportion of Li2Mo3S 13 in the lithium-ion cathode lithium supplementing material product is 2%.

[0066] Example 4

[0067] The difference from Example 1 is only that: the mass of the red-brown solid product (NH4)2Mo3S in step (3) 13 is 5 g, and the mass of Li5FeO4 is 95 g. In this example, the mass proportion of Li2Mo3S 13 in the lithium-ion cathode lithium supplementing material product is 5%.

[0068] Example 5

[0069] The difference from Example 1 is only that: the mass of the red-brown solid product (NH4)2Mo3S in step (3) 13 is 0.5 g, and the mass of Li5FeO4 is 99.5 g. In this example, the mass proportion of Li2Mo3S 13 in the lithium-ion cathode lithium supplementing material product is 99.5%.

[0070] Example 6

[0071] The difference from Example 1 is only that: heat to 750 °C at a heating rate of 5 °C / min (changing the sintering temperature).

[0072] Comparative Example 1

[0073] The difference from Example 1 is only that: do not add (NH4)2Mo3S 13 .

[0074] (1) Mix 42 g of lithium source LiOH and 160 g of transition metal source Fe2O3 (molar ratio 1.75:1) evenly to obtain a mixture. Place the mixture under an inert atmosphere, sinter it at 800 °C for 15 h, and crush it to obtain the core Li5FeO4.

[0075] (2) Grind and mix Li5FeO4 evenly, put it into a crucible, place it in a muffle furnace, under a methane protection atmosphere, heat it to 600 °C at a heating rate of 5 °C / min, keep it warm for 12 hours, and cool it naturally to room temperature.

[0076] (3) Take out the sintered powder, crush it with a ball mill, and pass it through a 200-mesh sieve to obtain a powder with a uniform particle size distribution.

[0077] Comparative Example 2

[0078] The difference from Example 2 is only that: (NH4)2Mo3S is not added 13 .

[0079] (1) Mix nickel sulfate and sodium hydroxide in a molar ratio of 1:0.01 and add them to deionized water to prepare an aqueous solution with a solid content of 20%. At the same time, add it to a reaction kettle for hydrothermal precipitation reaction, then filter, wash, dry at 150 °C, and sinter at 750 °C for 6 h to obtain NiO material.

[0080] (2) Weigh the NiO prepared in step (1) and lithium oxide according to the molar ratio of elements (nickel to lithium) of 1:1, and then put them into a high-energy ball mill and grind for 50 min at a rotation speed of 400 rpm to obtain a mixture.

[0081] (3) Load the mixture into a crucible, heat it to 300 °C at a heating rate of 2 °C / min in a sintering furnace under a methane protection atmosphere, keep it warm for 2 h, continue to heat it to 600 °C at a heating rate of 2 °C / min, keep it warm for 12 h, then cool it to room temperature at a rate of 2 °C / min, and then perform air flow crushing to obtain the lithium-rich lithium nickelate material Li2NiO2.

[0082] Test Example 1

[0083] Test the XRD pattern of (NH4)2Mo3S prepared in Example 1 13 as shown in Figure 1 . It can be seen that the XRD of the (NH4)2Mo3S 13 powder is consistent with the simulated XRD of the (NH4)2Mo3S 13 crystal structure.

[0084] Test Example 2

[0085] Test the residual alkali content of the cathode materials prepared in the examples and comparative examples and their performance after treatment under high humidity. The results are shown in Table 1.

[0086] Battery Assembly: A lithium-ion battery is prepared using a positive electrode plate, a separator, a negative electrode plate, and an electrolyte of a lithium-ion battery as raw materials by the same preparation method. The positive electrode plate, the separator, the negative electrode plate, and the electrolyte are composed as follows:

[0087] Positive Electrode Plate: The synthesized material, PVDF, and carbon black are mixed in a mass ratio of 90:5:5, using N-methylpyrrolidone as a dispersion medium, stirred, and prepared into a positive electrode slurry, which is coated on a positive electrode current collector and dried and roll-pressed to obtain a positive electrode plate.

[0088] Separator: Polypropylene film (PP separator).

[0089] Negative Electrode Plate: Graphite, PVDF, and carbon black are mixed in a mass ratio of 96:2:2, using N-methylpyrrolidone as a dispersion medium, stirred, and prepared into a negative electrode slurry, which is coated on a negative electrode current collector and dried and roll-pressed to obtain a negative electrode plate.

[0090] Electrolyte: 1M LiPF6 electrolyte, and the volume ratio of the solvents EC:EMC:DMC is 1:1:1.

[0091] The performance of the prepared battery is tested.

[0092] Table 1 Residual Alkali Content and Performance of the Positive Electrode Materials Prepared in Examples and Comparative Examples

[0093]

[0094] Table 1 shows the residual alkali content of the fresh materials in the examples and comparative examples, as well as the moisture content and the corresponding specific capacity after being placed in the air with 30% humidity for 24h. Compared with Comparative Example 1, Example 1 has a lower residual alkali, a weaker water reaction ability, and a higher specific capacity. Compared with Comparative Example 2, Example 2 has a lower residual alkali, a weaker water reaction ability, and a higher specific capacity. This proves the universality of the method provided by the present invention.

[0095] Figure 2 Scanning electron microscope images of the cross-section of the lithium ferrite core of the electrode plates made of the fresh materials of Example 1 and Comparative Example 1 and the electrode plates made after being placed in the air with 30% humidity for 24h. It can be seen that: the fine lines of the fresh cores of Example 1 and Comparative Example 1 are quite similar and there is no pulverization. After being placed in the air with 30% humidity for 24h, there are many cracks in the cores. Compared with Comparative Example 1, Example 1 has very few nano-scale cracks.

[0096] Figure 3Scanning electron microscope images of the cross-section of the lithium iron phosphate core of the electrode sheets made from fresh materials in Example 2 and Comparative Example 2 and the electrode sheets made after being placed in 30% air for 24 hours. It can be seen that, compared with the fresh cores in Example 2 and Comparative Example 2, there are fewer fine lines and no pulverization. After being placed in 30% air for 24 hours, there are a few cracks in the core of Example 2, while a large number of cracks occur in Comparative Example 2 and pulverization occurs.

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lithium-ion cathode lithium supplement material, characterized in that, The lithium-ion cathode lithium supplement material includes a main material and Li2Mo3S 13 .

2. The lithium-ion cathode lithium supplementing material according to claim 1, wherein In the lithium-ion cathode lithium supplement material, the mass fraction of Li2Mo3S 13 is 0.5%-2%; And / or, the host material of the lithium-ion cathode lithium supplementing material is selected from at least one of lithium ferrite, lithium nickelate and ternary cathode materials.

3. A method for preparing the lithium-ion cathode lithium supplementing material according to claim 1 or 2, characterized in that, Comprising: Provide (NH4)2Mo3S 13 Molecular cluster; (NH4)2Mo3S is added during the sintering stage of the main material preparation process 13 molecular clusters to generate the lithium conductor Li2Mo3S 13 .

4. The preparation method according to claim 3, wherein The described (NH4)2Mo3S 13 The preparation process of the molecular cluster includes: mixing an ammonium molybdate aqueous solution and an ammonium polysulfide solution, reacting at 80°C - 95°C for 1h - 3h, standing still to separate the solid material, and then washing and drying.

5. The preparation method according to claim 4, characterized in that, The concentration of the ammonium molybdate aqueous solution is 20 g / L - 50 g / L; And / or, the drying temperature is 120 °C - 140 °C.

6. The preparation method according to any one of claims 3-5, characterized in that, The host material of the lithium-ion cathode lithium supplementing material is lithium ferrite, and the preparation process comprises: Mix lithium ferrite and (NH4)2Mo3S 13 Molecular clusters are mixed and crushed, and then heat-insulated for 10h-15h under the condition of 500℃-700℃; Preferably, sintering is carried out under a methane protective gas.

7. The preparation method according to any one of claims 3-5, characterized in that, The host material of the lithium-ion cathode lithium supplementing material is lithium nickelate, and the preparation process comprises: Mix nickel oxide, a lithium source, and (NH4)2Mo3S 13 with a molecular cluster, keep it at 250 °C - 350 °C for 1 h - 3 h first, and then keep it at 500 °C - 700 °C for 10 h - 15 h; Preferably, sintering is carried out under a methane protective gas.

8. The preparation method according to claim 7, wherein The lithium source is selected from at least one of lithium oxide, lithium nitride and lithium sulfide.

9. A positive electrode sheet, characterized in that, Comprising the lithium-ion cathode lithium supplementing material described in any one of claims 1-2 or the lithium-ion cathode lithium supplementing material prepared by the preparation method described in any one of claims 3-8.

10. A lithium battery, characterized in that, Comprising the positive electrode sheet described in claim 9.

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