Lithium niobate-coated composite electrode material and preparation method and application thereof
By using surfactants to assist in the coating of lithium niobate on the surface of lithium nickel manganese oxide, a uniform lithium niobate coating is formed and combined with carbon coverage, which solves the structural instability and battery capacity decay problems of LNMO, improves battery performance and reduces production costs.
Patent Information
- Application Number
- CN202511216828.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-11-21
AI Technical Summary
Existing lithium nickel manganese oxide (LNMO) materials suffer from structural instability caused by Mn3+, manganese dissolution, and battery capacity decay in lithium-ion batteries. Furthermore, non-in-situ coating methods are costly and difficult to control the coating thickness.
A surfactant-assisted non-in-situ coating of lithium nickel manganese oxide with lithium niobate was used. By forming a uniform lithium niobate coating on the surface of lithium nickel manganese oxide and then performing high-temperature treatment to achieve carbon coverage, the electronic conductivity and ionic conductivity were improved.
It improves the cycle stability and rate performance of lithium nickel manganese oxide materials, reduces process and energy costs, and is suitable for LNMO materials synthesized by various methods.
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Figure CN120998975A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of battery materials, and particularly relates to a lithium niobate-coated composite electrode material and a preparation method and application thereof. BACKGROUND
[0002] The increasing depletion of traditional fossil energy and the intermittent nature of renewable energy (such as wind energy and solar energy) make efficient energy storage technology a key to the large-scale application of clean energy. Lithium ion batteries have become one of the mainstream technologies in the energy storage field due to their high energy density, long cycle life and excellent electrochemical performance.
[0003] As an indispensable part of lithium ion batteries, the positive electrode material largely determines the overall performance of the battery. However, the current mainstream commercial positive electrode materials each have different limitations and are difficult to meet the urgent demand for high energy density, low cost and high safety batteries in emerging fields such as electric vehicles. Lithium nickel manganese oxide material LiNi 0.5 Mn 1.5 O4 (LNMO) is one of the most likely high-voltage positive electrode materials for lithium ion batteries to achieve commercial application at present. It has a voltage platform as high as 4.7V (vs. Li / Li + ), making its theoretical energy density reach 650Wh·kg -1 . At the same time, the material itself does not contain cobalt elements, which can significantly reduce the dependence on cobalt. In addition, its synthesis process has strong compatibility with the existing ternary positive electrode material production line, and has the potential for scale-based cost reduction. It is expected to realize high-performance lithium ion batteries with low cost and high energy density and power density.
[0004] Although LNMO has the above advantages, its commercialization process is still restricted by multiple factors, with the key bottleneck being the decline in structural stability and manganese dissolution caused by the presence of Mn 3+ in the material. Although theoretically the manganese element in LNMO should all be in the four-valence state and only play a role in stabilizing the structure without participating in the redox reaction, in actual synthesis and charging and discharging processes, Mn 3+ is inevitably generated due to oxygen vacancies or side reactions. The presence of Mn 3+ can indeed improve the intrinsic conductivity of the material and thus improve the rate performance of the battery, but when Mn 3+ comes into contact with HF generated due to trace water in the electrolyte, disproportionation reaction occurs, and the generated Mn 2+ dissolves into the electrolyte, destroying the crystal structure and generating adverse SEI byproducts, thereby causing the capacity of the battery to decay. At the same time, Mn 3+ and Mn 4+The Jahn-Teller distortion occurring when the valence state changes can also periodically trigger the distortion-relaxation process, causing particle microcracks and active material peeling, which can also cause the capacity of the battery to decay. In addition, although LNMO has three-dimensional lithium ion diffusion channels, its own ion conductivity is not high, which limits its application in high-power scenarios, which is also a major defect that cannot be ignored. In view of the above problems existing in LNMO, the commonly recognized modification ideas of researchers at present are two, one is doping modification, and the other is coating modification.
[0005] Doping modification refers to introducing doping elements into the LNMO lattice to achieve the effect of inhibiting lattice distortion, reducing structural collapse, and stabilizing the crystal structure, but it is difficult to accurately control the concentration of doping and the uniform distribution of doping elements in the actual synthesis process, and it is difficult to ensure the consistency of performance.
[0006] Coating modification is to use other materials to coat on the surface of LNMO through physical or chemical combination to alleviate the dissolution of Mn ions, stabilize the interface between LNMO and electrolyte, reduce the side reaction between LNMO and electrolyte, and improve the performance of the battery. From the perspective of preparation process, coating modification can be divided into in-situ coating and non-in-situ coating. In-situ coating can realize the combination of coating layer and matrix through synchronous growth, for example, the existing technology Y. Han et al. successfully converted the spinel phase on the surface of LNMO into a layered phase and a rock salt phase by a hydrothermal method, which is equivalent to in-situ coating a layered phase and a rock salt phase on the surface of LNMO. The rock salt phase can inhibit the dissolution of Mn and provide inert protection, and the layered phase provides electrochemical activity and supports charge transfer, achieving a balance between stabilizing the material structure and improving charge transfer, and obtaining excellent cycle performance and excellent rate performance. However, the problem of in-situ coating is that the type of coating layer is limited by the reactivity of the precursor, and cannot be flexibly selected, and it is difficult to control the thickness of the coating layer in the actual synthesis process. In addition, non-in-situ coating is to attach the pre-synthesized coating material to the surface of the particle after the synthesis of the matrix material is completed, and the advantage is that it does not need to consider the limitation of the matrix, and the type of coating layer can be flexibly selected, but the coating effect is often not as good as that of in-situ coating. If you want to finely control the thickness of the coating layer, you need to use ALD / CVD equipment, which is expensive and not conducive to large-scale production. SUMMARY
[0007] The purpose of the present application is to provide a preparation method of lithium niobate coated composite electrode material to solve the problems raised in the background art.
[0008] To achieve the above purpose, the embodiments of the present application provide the following technical solutions:
[0009] A preparation method of lithium niobate coated composite electrode material, comprising the following steps:
[0010] dispersing the lithium nickel manganese oxide material into a solvent, then adding lithium niobate and a surfactant to mix to obtain a mixed solution; a mass ratio of the lithium niobate, the surfactant and the lithium nickel manganese oxide material is (0.5-5):(0.5-5):100;
[0011] heating and stirring the mixed solution, and removing the solvent to obtain a semi-finished product;
[0012] calcining the semi-finished product to obtain a composite electrode material.
[0013] Preferably, the lithium nickel manganese oxide material is LiNi 0.5 Mn 1.5 O4.
[0014] Preferably, the solvent is anhydrous ethanol.
[0015] Preferably, the surfactant is one or more of cocamidopropyl betaine, lauramidopropyl betaine, cocamide diethanolamine, polyoxyethylene laurylamine, polyvinylpyrrolidone, methyl glucoside sesqui-stearate, decaglyceryl decaoleate.
[0016] Preferably, the surfactant is polyvinylpyrrolidone.
[0017] Preferably, the temperature of the heating and stirring is 80-150°C.
[0018] Preferably, the temperature of the calcining is 600-900°C.
[0019] Another purpose of the embodiment of the present application is to provide a lithium niobate-coated composite electrode material prepared by the above preparation method.
[0020] Another purpose of the embodiment of the present application is to provide an application of the above lithium niobate-coated composite electrode material in the preparation of a lithium ion battery.
[0021] Another purpose of the embodiment of the present application is to provide a lithium ion battery comprising a positive electrode and a negative electrode, wherein the positive electrode comprises the above lithium niobate-coated composite electrode material.
[0022] The preparation method of the lithium niobate-coated composite electrode material provided by the present application uses a surfactant to assist in situ coating of lithium niobate on lithium nickel manganese oxide, and by introducing the surfactant and lithium niobate during the coating process, the smoothness and uniformity of the coating are ensured, and the electronic conductivity and ionic conductivity of the coating layer are also considered, thereby improving the cycle stability of the lithium nickel manganese oxide material and significantly improving the rate performance of the lithium nickel manganese oxide material. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The figure is a comparison of the cycle performance of the embodiment 1 and the comparative example 1 of the present application, and is tested at room temperature 0.5C rate, and the voltage range is 3.5-4.9V.
[0024] Figure 2 The figure is a comparison of the charge-discharge rate performance of the embodiment 1 and the comparative example 1 of the present application, and the test rates are 0.1C, 0.2C, 0.5C, 1C, 2C, 5C in turn.
[0025] Figure 3 The figure is a comparison of the discharge rate performance of the embodiment 1 and the comparative example 1 of the present application, and the charge rate is constant at 0.5C, and the discharge rates are 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 20C in turn.
[0026] Figure 4 The figure is an XRD diffraction pattern of the embodiment 1 and the comparative example 1 of the present application.
[0027] Figure 5 The figure is an SEM image of the embodiment 1 of the present application.
[0028] Figure 6 The figure is Figure 5 The figure is a corresponding Nb element surface distribution map. DETAILED DESCRIPTION
[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0030] In an embodiment of the present application, a preparation method of a lithium niobate coated composite electrode material is provided, comprising the following steps:
[0031] S1, dispersing the lithium nickel-manganese oxide material into a solvent, then adding lithium niobate and a surfactant, and stirring and mixing at a speed of 200-800 rpm for 0.5-3 h to obtain a mixed solution; the mass ratio of lithium niobate, surfactant and lithium nickel-manganese oxide material is (0.5-5):(0.5-5):100, preferably (0.8-1.5):(0.8-1.5):100, and more preferably 1:1:100.
[0032] S2, heating and stirring the mixed solution to remove the solvent to obtain a semi-finished product.
[0033] S3, calcining the semi-finished product to obtain a composite electrode material.
[0034] In a preferred embodiment of the present application, the lithium nickel manganese oxide material is LiNi 0.5 Mn 1.5 O4(LNMO). It should be noted that the LNMO can be directly used as a commercially available product, or can be prepared by a solid phase method, a coprecipitation method, a hydrothermal / solvothermal method or a sol-gel method, but is not limited thereto; the lithium niobate (LiNbO3) can be directly used as a commercially available product, or can be prepared by a solid phase method, a coprecipitation method, a hydrothermal / solvothermal method or a sol-gel method, but is not limited thereto.
[0035] In a preferred embodiment of the present application, the solvent is anhydrous ethanol, but is not limited thereto, and other organic or inorganic solvents capable of dissolving or dispersing the lithium nickel manganese oxide material can also be used.
[0036] In a preferred embodiment of the present application, the surfactant is one or more of cocamidopropyl betaine, lauramidopropyl betaine, cocamide diethanolamine, polyoxyethylene laurylamine, polyvinylpyrrolidone, methyl glucoside sesqui-stearate and decaglyceryl decaoleate, but is not limited thereto. Preferably, the surfactant is polyvinylpyrrolidone; the amide group in the polyvinylpyrrolidone can be combined with the hydroxyl group on the surface of the lithium nickel manganese oxide and the lithium niobate through hydrogen bonding or dipole interaction, thereby playing a bridging role to connect the lithium nickel manganese oxide and the lithium niobate together, and at the same time, the steric hindrance effect of the polyvinylpyrrolidone further ensures the uniformity of the dispersion of the lithium niobate on the surface of the lithium nickel manganese oxide; in addition, the excellent solubility and excellent chemical inertness of the polyvinylpyrrolidone also ensure the smooth progress of the entire synthesis process.
[0037] In a preferred embodiment of the present application, the temperature for heating and stirring is 80-150°C, and an oil bath heating can be used, and the stirring speed is 200-800 rpm.
[0038] In a preferred embodiment of the present application, the temperature for calcination is 600-900°C, the time is 0.5-3h, the heating rate is 3-8°C / min, and the atmosphere used during calcination is any one of air, argon, nitrogen and oxygen.
[0039] In another embodiment of the present application, a lithium ion battery is also provided, which includes a positive electrode and a negative electrode, and the positive electrode includes the lithium niobate-coated composite electrode material described above; of course, the lithium ion battery can also include an electrolyte and a diaphragm and other components, and the structure of the lithium ion battery can refer to the prior art, which will not be described here.
[0040] In the embodiment of the present application, a method for non-in situ coating of lithium nickel manganese oxide using surfactant-assisted lithium niobate is provided. Compared with the traditional non-in situ coating method, the advantages of the method are as follows: on the one hand, the introduction of the surfactant improves the dispersion uniformity of the coating material lithium niobate on the surface of LNMO, ensuring the uniformity and smoothness of the coating; on the other hand, the surfactant will be carbonized during high-temperature treatment, which is equivalent to realizing carbon coating at the same time, so that the coating layer has both electronic conductivity and ionic conductivity, thereby improving the cycle life of LNMO while enhancing its rate performance. In addition, it is worth noting that the preparation method provided in the embodiment of the present application only involves simple mechanical stirring and short-time high-temperature treatment, which greatly saves the process and energy costs, has strong universality, can be applied to LNMO prepared by various synthesis methods, has different morphologies, and has the potential for large-scale application due to its simple process flow and easy operation.
[0041] The following examples are some specific implementation cases of the present application in actual application, but are not limited thereto.
[0042] Example 1: The embodiment provides a preparation method of a lithium niobate-coated composite electrode material, comprising the following steps:
[0043] S1, 1g of LNMO is dispersed in 50mL of anhydrous ethanol, and stirring is performed for 0.5h to complete the dispersion, then 10mg of LiNbO3 and 10mg of polyvinylpyrrolidone (PVP) are added, and stirring and mixing are performed at a speed of 500rpm for 0.5h to obtain a mixed solution.
[0044] LNMO is synthesized by a sol-gel method, and the specific synthesis method is as follows: the amounts of lithium acetate, nickel acetate and manganese acetate corresponding to the contents of the components in LNMO are calculated, wherein the amount of lithium acetate should be relatively more by 5%-10% (more by 8% in this embodiment). After weighing, the lithium acetate, nickel acetate and manganese acetate are dissolved in anhydrous ethanol to obtain solution A, and then the corresponding amount of citric acid (the molar ratio of citric acid to total metal ions is 1:1) is also dissolved in anhydrous ethanol to obtain solution B. Then, solutions A and B are simultaneously added to anhydrous ethanol, and stirring is performed under heating at 80℃. After aging for half an hour, the gel is collected and dried at 100℃ for 12h. After drying, the sample is sintered in a muffle furnace at 650℃ for 5h, and then ball-milled for 3h and calcined at 800℃ for 10h to obtain LNMO.
[0045] LiNbO3 is also synthesized by sol-gel method, which is similar to the synthesis method of LNMO described above, except that the nickel acetate and manganese acetate in the precursor salt are replaced by ammonium niobate oxalate hydrate, and the sintering temperature of the muffle furnace is 600°C; the specific steps are as follows: according to the content of each component in LiNbO3, the amount of lithium acetate and ammonium niobate oxalate hydrate is calculated, wherein the amount of lithium acetate should be relatively more by 5%-10% (in this embodiment, more by 8%). After weighing, dissolve it in anhydrous ethanol, mark it as solution C, then weigh the corresponding amount of citric acid (the molar ratio of citric acid to total metal ions is 1:1) and also dissolve it in anhydrous ethanol, mark it as solution D. Then add solution C and D into anhydrous ethanol at the same time, heat and stir at 80°C, age for half an hour, then collect the gel and dry at 100°C for 12h. After drying, the sample is sintered in a muffle furnace at 600°C for 5h, ball milled for 3h, then calcined at 800°C for 10h, and LiNbO3 is obtained.
[0046] S2, transfer the above mixed solution to an oil bath pot and heat to 80°C, stir until the ethanol is evaporated, then transfer to an oven and dry at 80°C for 12h, then grind to obtain a semi-finished product.
[0047] S3, place the above semi-finished product in a muffle furnace, heat to 850°C at a heating rate of 5°C / min in an air atmosphere, and calcine for 2h to obtain a composite electrode material.
[0048] Example 2: This example provides a preparation method of lithium niobate coated composite electrode material, which is basically the same as example 1, except that the LNMO synthesized by sol-gel method is replaced by LNMO synthesized by existing technology of molten salt method.
[0049] Example 3: This example provides a preparation method of lithium niobate coated composite electrode material, which is basically the same as example 1, except that the LNMO synthesized by sol-gel method is replaced by LNMO synthesized by existing technology of co-precipitation method.
[0050] Example 4: This example provides a preparation method of lithium niobate coated composite electrode material, which comprises the following steps:
[0051] S1, disperse 1g of LNMO in 50mL of anhydrous ethanol, stir for 0.5h to complete dispersion, then add 8mg of LiNbO3 and 15mg of cocamide propyl betaine, and stir and mix at a speed of 200rpm for 3h to obtain a mixed solution. The synthesis method of LNMO and LiNbO3 is the same as example 1.
[0052] S2, transfer the above mixed solution to an oil bath pot and heat to 80°C, stir until the ethanol is evaporated, then transfer to an oven and dry at 80°C for 12h, then grind to obtain a semi-finished product.
[0053] S3, place the semi-finished product in a muffle furnace, and calcine at 600°C under an air atmosphere at a temperature increasing rate of 3°C / min for 3h to obtain a composite electrode material.
[0054] Example 5: The embodiment provides a preparation method of a lithium niobate coated composite electrode material, comprising the following steps:
[0055] S1, disperse 1g of LNMO in 50mL of anhydrous ethanol, complete dispersion after stirring for 0.5h, then add 15mg of LiNbO3, 4mg of lauryl amidopropyl betaine and 4mg of cocamide diethanolamine, and stir and mix at a speed of 800rpm for 0.5h to obtain a mixed solution. The synthesis method of LNMO and LiNbO3 is the same as that in Example 1.
[0056] S2, transfer the mixed solution into an oil bath pot and heat to 150°C, stir until the ethanol is evaporated, then transfer into an oven and dry at 80°C for 12h, then grind to obtain a semi-finished product.
[0057] S3, place the semi-finished product in a muffle furnace, and calcine at 900°C under an air atmosphere at a temperature increasing rate of 8°C / min for 0.5h to obtain a composite electrode material.
[0058] Example 6: The embodiment provides a preparation method of a lithium niobate coated composite electrode material, comprising the following steps:
[0059] S1, disperse 1g of LNMO in 50mL of anhydrous ethanol, complete dispersion after stirring for 0.5h, then add 15mg of LiNbO3, 4mg of lauryl amidopropyl betaine and 4mg of cocamide diethanolamine, and stir and mix at a speed of 800rpm for 0.5h to obtain a mixed solution. The synthesis method of LNMO and LiNbO3 is the same as that in Example 1.
[0060] S2, transfer the mixed solution into an oil bath pot and heat to 150°C, stir until the ethanol is evaporated, then transfer into an oven and dry at 80°C for 12h, then grind to obtain a semi-finished product.
[0061] S3, place the semi-finished product in a muffle furnace, and calcine at 900°C under an air atmosphere at a temperature increasing rate of 8°C / min for 0.5h to obtain a composite electrode material.
[0062] Example 7: The embodiment provides a preparation method of a lithium niobate coated composite electrode material, comprising the following steps:
[0063] S1, 1 g of LNMO was dispersed in 50 mL of anhydrous ethanol, and stirring was performed for 0.5 h to complete the dispersion, then 50 mg of LiNbO3, 20 mg of methyl glucoside sesqui-stearate and 30 mg of decaglycerol decaoleate were added, and stirring and mixing were performed at a rotation speed of 600 rpm for 1.5 h to obtain a mixed solution. The synthesis method of LNMO and LiNbO3 was the same as that in Example 1.
[0064] S2, the above mixed solution was transferred to an oil bath pot and heated to 120℃, and stirring was performed until the ethanol was evaporated, then it was transferred to an oven and dried at 80℃ for 12 h, and then grinding was performed to obtain a semi-finished product.
[0065] S3, the above semi-finished product was placed in a muffle furnace, and calcination treatment was performed at a temperature rising rate of 6℃ / min to 700℃ under an air atmosphere for 1.5 h to obtain a composite electrode material.
[0066] Comparative Example 1: This comparative example provides a lithium nickel manganese oxide material LNMO which is not coated, and the synthesis method is the same as that in Example 1.
[0067] Performance test: I. The lithium niobate coated composite electrode material prepared in Example 1 and the LNMO prepared in Comparative Example 1 were compared in terms of cycle performance and capacity retention rate under the condition of room temperature 0.5C rate and voltage range of 3.5-4.9V, and the results are shown in Figure 1 and Table 1.
[0068] Table 1
[0069] Test object Test range Test rate Initial capacity Capacity retention after 300 cycles Example 1 3.5-4.9V 0.5C 124.96 mAh / g 80.44% Comparative Example 1 3.5-4.9V 0.5C 114.02 mAh / g 87.70%
[0070] From Figure 1 and Table 1, it can be seen that the lithium niobate coated composite electrode material (LNMO+LiNbO3 in the figure) prepared in the example of the present application has a more excellent capacity retention rate compared with the unmodified LNMO, which indicates that a smooth and uniform coating layer is formed on the surface of LNMO with the help of the surfactant, the dissolution of Mn is inhibited, and the cycle stability of the material is improved.
[0071] II. The lithium niobate coated composite electrode material prepared in Example 1 and the LNMO prepared in Comparative Example 1 were compared in terms of charge-discharge rate performance, and the test rates were 0.1C, 0.2C, 0.5C, 1C, 2C, 5C in turn, and the results are shown in Figure 2 . The lithium niobate coated composite electrode material prepared in Example 1 and the LNMO prepared in Comparative Example 1 were compared in terms of discharge rate performance, and the charge rate was constant at 0.5C, and the discharge rates were 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 20C in turn, and the results are shown in Figure 3 . From Figure 2 and Figure 3It can be seen that the rate performance of the lithium niobate coated composite electrode material (LNMO+LiNbO3 in the figure) prepared by the embodiment of the present application is obviously improved compared with the unmodified LNMO, which proves that LiNbO3 as a coating layer enhances the lithium ion diffusion capacity of LNMO.
[0072] III. The lithium niobate coated composite electrode material (LNMO+LiNbO3 in the figure) prepared in Example 1 and the LNMO prepared in Comparative Example 1 were compared by XRD, and the results are shown in Figure 4 It can be seen from the figure that the preparation method provided by the embodiment of the present application does not change the crystal structure of LNMO.
[0073] IV. The lithium niobate coated composite electrode material prepared in Example 1 was characterized by SEM, and the results are shown in Figure 5 The corresponding Nb element distribution is shown in Figure 6 It can be seen from the figure that the preparation method provided by the embodiment of the present application can successfully coat LiNbO3 on the surface of LNMO.
[0074] In summary, by introducing a surfactant and LiNbO3 to coat lithium nickel manganese oxide in situ during the coating process, the embodiment of the present application not only ensures the smoothness and uniformity of the coating, but also takes into account the electronic conductivity and ionic conductivity of the coating layer, improves the rate performance of LNMO on the basis of improving the cycle stability of LNMO.
[0075] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification.
Claims
1. A method for preparing a lithium niobate-coated composite electrode material, characterized in that, Includes the following steps: Lithium nickel manganese oxide material is dispersed in a solvent, and then lithium niobate and a surfactant are added and mixed to obtain a mixed solution; the mass ratio of lithium niobate, surfactant and lithium nickel manganese oxide material is (0.5-5):(0.5-5):100; The mixed solution is heated and stirred to remove the solvent, yielding a semi-finished product; The semi-finished product is calcined to obtain the composite electrode material.
2. The method for preparing the lithium niobate-coated composite electrode material according to claim 1, characterized in that, The lithium nickel manganese oxide material is LiNi 0.5 Mn 1.5 O4.
3. The method for preparing the lithium niobate-coated composite electrode material according to claim 1, characterized in that, The solvent is anhydrous ethanol.
4. The method for preparing the lithium niobate-coated composite electrode material according to claim 1, characterized in that, The surfactant is one or more of the following: cocamidopropyl betaine, lauramide propyl betaine, cocamidodiethanolamine, polyoxyethylene lauramide, polyvinylpyrrolidone, methyl glucoside sesquistearate, and decaglycerol decaoleate.
5. The method for preparing the lithium niobate-coated composite electrode material according to claim 4, characterized in that, The surfactant is polyvinylpyrrolidone.
6. The method for preparing the lithium niobate-coated composite electrode material according to claim 1, characterized in that, The heating and stirring temperature is 80-150℃.
7. The method for preparing the lithium niobate-coated composite electrode material according to claim 1, characterized in that, The calcination temperature is 600-900℃.
8. A lithium niobate-coated composite electrode material prepared by any one of the preparation methods described in claims 1-7.
9. The application of the lithium niobate-coated composite electrode material as described in claim 8 in the preparation of lithium-ion batteries.
10. A lithium-ion battery, comprising a positive electrode and a negative electrode, characterized in that, The positive electrode comprises the lithium niobate-coated composite electrode material as described in claim 8.