Double anion type poly silicate nanometer material composite modified precursor material and preparation method, modified positive electrode material, lithium ion battery

Abstract

The application provides a precursor of a double anionic polybasic silicate nanomaterial composite modification, which comprises a precursor body and a double anionic polybasic silicate nanomaterial, wherein the double anionic polybasic silicate nanomaterial is compounded on the surface of the precursor body; the molecular formula of the double anionic polybasic silicate is KN x Si4O 10 F2, wherein N is one or more of Li, Ni and Mg, and the value range of x is 2-3; the chemical formula of the precursor body is Ni m Mn n Co 1‑m‑n (OH)2, wherein the value range of m and n is 0.5<=m<=0.8 and 0.2<=n<=0.5. The mechanical strength and corrosion resistance of the precursor material are obviously improved. The application further provides a preparation method of the precursor, a corresponding positive electrode material and a positive electrode material prepared by using the modified precursor. The positive electrode material prepared by using the modified precursor not only has improved mechanical strength and corrosion resistance, but also has improved conductivity and ion transmission performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion battery manufacturing, and particularly relates to a double-anion type multi-element silicate nanomaterial composite modified lithium battery precursor material, a preparation method thereof, a modified positive electrode material and a lithium ion battery. BACKGROUND

[0002] The rapid development of lithium ion batteries further promotes the development and research of battery materials. The ternary material is the most widely used electrode material among all positive electrode materials, has high electrical conductivity and high rate capacity. However, in the continuous electrochemical reaction process, the structure of the material is prone to cracking, which causes the electrolyte to continuously corrode into the internal structure of the main body, and finally causes irreversible capacity decay of the battery.

[0003] In view of these problems, the most common modification method is coating and doping. For coating modification, the choice of coating material is crucial. The poly-anion type material such as silicate material can effectively improve the structural stability and corrosion resistance of the ternary material due to its high structural strength and good chemical stability. However, this type of material also has some inherent defects, such as poor electrical conductivity and low ion diffusion rate. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the background art. The present application provides a double-anion type multi-element silicate nanomaterial composite modified lithium battery precursor material, a preparation method thereof, a modified positive electrode material and a lithium ion battery.

[0005] In view of the above technical problems, the following solutions are proposed:

[0006] The first object of the present application is to provide a double-anion type multi-element silicate nanomaterial composite modified precursor, which comprises a precursor body and a double-anion type multi-element silicate nanomaterial, wherein the double-anion type multi-element silicate nanomaterial is compounded on the surface of the precursor body; the molecular formula of the double-anion type multi-element silicate is KN x Si4O 10 F2, wherein N is one or more of Li, Ni and Mg, and the value range of x is 2-3; the chemical formula of the precursor body is Ni m Mn n Co 1-m-n (OH)2, wherein the value range of m and n is 0.5≤m≤0.8 and 0.2≤n≤0.5.

[0007] The second object of the present application is to provide a preparation method of the double-anion type multi-element silicate nanomaterial composite modified precursor, which comprises:

[0008] (1) uniformly mixing a potassium source, a silicon source, a fluorine source and a doping metal source by solid phase mechanical mixing, and then sintering at high temperature to obtain a dual-anion multi-silicate nanomaterial; the doping metal is selected from one or more of Li, Ni and Mg;

[0009] (2) preparing a mixed metal salt solution A of nickel salt, cobalt salt and manganese salt, a precipitant solution and a complexing agent solution; under a protective atmosphere, the mixed metal salt solution A, the precipitant solution and the complexing agent solution are passed into a reactor in parallel to perform a co-precipitation reaction, thereby obtaining a Ni m Mn n Co 1-m-n (OH)2 precursor slurry;

[0010] (3) adding the dual-anion multi-silicate nanomaterial to the precursor slurry, continuing to stir for a certain period of time, and then washing and drying the obtained solid after solid-liquid separation, thereby obtaining the product.

[0011] Preferably, in step (1), the silicon source is one or both of silicon dioxide and silicic acid;

[0012] The potassium source is one or more of potassium oxide, potassium carbonate, potassium nitrate and potassium acetate;

[0013] The doping metal source is one or more of lithium oxide, nickel oxide, magnesium oxide, lithium carbonate, magnesium carbonate, lithium nitrate, magnesium nitrate, lithium acetate and magnesium acetate;

[0014] The fluorine source is one or both of NH4HF2 and NH4F.

[0015] Preferably, in step (1), the molar ratio of potassium in the potassium source to the silicon source, the fluorine source and the doping metal source is 1:4:2:(2-3).

[0016] Preferably, in step (1), the sintering temperature is 700-1000°C, and the sintering time is 8-20h.

[0017] Preferably, in step (3), the molar ratio of the precursor to the dual-anion multi-silicate is 1:(0.03-0.08).

[0018] Preferably, in step (2), the manganese salt, the nickel salt and the cobalt salt are one or more of nitrate, acetate and sulfate; and the total metal concentration of the mixed metal salt solution is 1-3 mol / L.

[0019] The precipitant solution is a sodium hydroxide solution; and the concentration of the precipitant solution is 4-6 mol / L.

[0020] The complexing agent is an ammonia water solution; the concentration of the ammonia water solution is 15-25 wt%.

[0021] Preferably, in step (2), the pH value of the reaction system in the co-precipitation process is controlled to be 10-12.

[0022] The co-precipitation reaction time is 30-60 h.

[0023] A third object of the present application is to provide a modified positive electrode material, which is obtained by mixing the precursor as described above with a lithium source and then performing two-stage sintering.

[0024] Preferably, the molar ratio of the precursor to the lithium source is 1: (1.03-1.05).

[0025] Preferably, the two-stage sintering includes low-temperature pre-sintering and high-temperature sintering; the temperature of the low-temperature pre-sintering is 300-500℃, the time of the low-temperature pre-sintering is 1-8 h; the temperature of the high-temperature sintering is 800-1100℃, and the time of the high-temperature sintering is 10-30 h.

[0026] A fourth object of the present application is to provide a lithium ion battery comprising the modified positive electrode material as described above.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] (1) The present application uses nano double anion type multi-silicate KN x Si4O 10 F2 to modify the precursor body Ni m Mn n Co 1-m-n (OH)2, which not only effectively improves the mechanical strength and corrosion resistance of the precursor, but also improves the electrical conductivity and ion transport performance of the material.

[0029] (2) The present application synthesizes nano double anion type multi-silicate by one-step solid phase method, and further composites the prepared double anion type multi-silicate on the surface of lithium battery precursor material by in-situ compounding method. The coating of double anion type multi-silicate can effectively improve the mechanical strength and corrosion resistance of the precursor material. And because the double anion type multi-silicate structure contains potassium metal ions inside, it can effectively improve the electrical conductivity of the material, and the double anion type multi-silicate has a larger interlayer spacing than the positive electrode material itself, which is beneficial to the rapid transport of lithium ions.

[0030] (3) In the present application, the lithiumization sintering process of the precursor is divided into two-stage sintering, wherein the low-temperature pre-calcination of the first stage is to promote the effective contact of the main body material and the coating layer, so that the coating layer can be more stably compounded on the surface of the main body material, and the low-temperature pre-calcination makes the structure of the precursor more ordered, thereby effectively improving the structural stability of the positive electrode material.

[0031] (4) The preparation process of the present application is simple, the process is short, the raw materials are easy to obtain, no toxic and harmful substances are generated in the preparation process, and the large-scale production is easy to realize. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The SEM of the KLiNi2Si4O12 material prepared in step (1) of Example 1 of the present application. 10 The SEM of the KLiNi2Si4O12 material prepared in step (1) of Example 1 of the present application.

[0034] Figure 2 The SEM of the KLiNi2Si4O12 material prepared in step (1) of Example 1 of the present application. 10 The XRD of the KLiNi2Si4O12 material prepared in step (1) of Example 1 of the present application.

[0035] Figure 3 The SEM of the product in Example 1 of the present application. DETAILED DESCRIPTION

[0036] In order to facilitate understanding of the present application, the following will combine the drawings of the specification and the preferred embodiments to make a more comprehensive and detailed description of the present application, but the protection scope of the present application is not limited to the following specific embodiments.

[0037] Example 1

[0038] (1) 16 mmol of SiO2, 8 mmol of NiO, 2 mmol of Li2O, 2 mmol of K2O and 8 mmol of NH4F were ball-milled uniformly, and then sintered at 800 ℃ for 10 h in a muffle furnace to obtain the material. The SEM test result is shown in Figure 1 From the figure, it can be seen that the material is a nanoparticle with uniform size distribution, about 80-100 nm, and the particles are not agglomerated. The XRD of the material is shown in Figure 2 From the figure, it can be seen that the synthesized product is a KLiNi2Si4O12 material. 10 F2 material.

[0039] (2) 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O were dissolved in deionized water to prepare a mixed metal salt solution with a metal ion concentration of 2 mol / L, and then the mixed metal salt solution, 4 mol / L NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added into a continuously stirred tank reactor under the protection of a nitrogen atmosphere, the pH of the system solution was controlled to be in the range of 10-11, and the reaction was carried out for 54 h to prepare a NiMnCo(OH)2 precursor slurry. -1 -1 0.6 0.2 0.2 (OH)2 precursor slurry.

[0040] (3) 4 mmol KLiNi2Si4O 10 F2 material in step (1) was added to the above-mentioned 0.1 mol precursor slurry, and after the reaction was continued for 1 h, the product was dried at 120℃ for 12 h, then 0.104 mol of LiOH was mechanically mixed with the above-synthesized ternary precursor, and the mixture was placed in a muffle furnace for high-temperature sintering, pre-sintered at 350℃ for 2 h, and then sintered at 930℃ for 10 h to obtain KLiNi2Si4O 10 F2@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0041] (1) The SEM image of the product is shown in Figure 3 , and it can be seen from Figure 3 that the product is in the form of micron-sized blocks, the material size is uniform, and the distribution is relatively dense.

[0042] Comparative Example 1

[0043] (1) 16 mmol SiO2 and 4 mmol K2O were uniformly ball-milled, and then sintered at 800℃ for 10 h in a muffle furnace to obtain K2Si4O9 material.

[0044] (2) 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O were dissolved in deionized water to prepare a mixed metal salt solution with a metal ion concentration of 2 mol / L, and then the mixed metal salt solution, 4 mol / L NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added into a continuously stirred tank reactor under the protection of a nitrogen atmosphere, the pH of the system solution was controlled to be in the range of 10-11, and the reaction was carried out for 54 h to prepare a NiMnCo(OH)2 precursor slurry. -1 -1 ​​​​​NaOH precipitant solution and 20 wt% NH3H2O complexing agent solution were added into the continuous stirred tank reactor, and the pH of the system solution was controlled to be in the range of 10-11. After 54 h of sufficient reaction, Ni 0.6 Mn 0.2 Co 0.2 (OH)2 precursor slurry was prepared.

[0045] (3) 4 mmol of K2Si4O9 material in step (1) was added to the 0.1 mol of precursor slurry prepared above, and after 1 h of continuous stirring reaction, it was dried at 120°C for 12 h. Then, 0.104 mol of LiOH was mechanically mixed with the above-synthesized ternary precursor, and placed in a muffle furnace for high-temperature sintering. After pre-sintering at 350°C for 2 h, further high-temperature sintering at 930°C for 10 h was carried out to obtain K2Si4O9@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0046] Comparative Example 2

[0047] (1) 16 mmol of SiO2, 8 mmol of NiO, 2 mmol of Li2O and 2 mmol of K2O were uniformly ball-milled, and then high-temperature sintered at 800°C for 10 h in a muffle furnace to obtain KLiNi2Si4O 11 material.

[0048] (2) 0.06 mol of NiSO4·7H2O, 0.02 mol of CoSO4·6H2O and 0.02 mol of MnSO4·H2O were dissolved in deionized water to prepare a mixed metal salt solution with a metal ion concentration of 2 mol L -1 -1. Then, under the protection of a nitrogen atmosphere, the mixed metal salt solution, 4 mol L -1 NaOH precipitant solution and 20 wt% NH3H2O complexing agent solution were added into the continuous stirred tank reactor, and the pH of the system solution was controlled to be in the range of 10-11. After 54 h of sufficient reaction, Ni 0.6 Mn 0.2 Co 0.2 (OH)2 precursor slurry was prepared.

[0049] (3) 4 mmol of K2Si4O9 material in step (1) was added to the 0.1 mol of precursor slurry prepared above, and after 1 h of continuous stirring reaction, it was dried at 120°C for 12 h. Then, 0.104 mol of LiOH was mechanically mixed with the above-synthesized ternary precursor, and placed in a muffle furnace for high-temperature sintering. After pre-sintering at 350°C for 2 h, further high-temperature sintering at 930°C for 10 h was carried out to obtain K2Si4O9@LiNi 11The material was added to the above 0.1 mol precursor slurry, and the reaction was continued with stirring for 1 h. After drying at 120 °C for 12 h, 0.104 mol of LiOH was mechanically mixed with the synthesized ternary precursor and then sintered in a muffle furnace. The mixture was first pre-calcined at 350 °C for 2 h, and then sintered at 930 °C for 10 h to obtain KLiNi2Si4O. 11 @LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0050] Comparative Example 3

[0051] (1) 16 mmol SiO2, 8 mmol NiO, 2 mmol Li2O, 2 mmol K2O and 8 mmol NH4F were ball-milled until homogeneous, and then sintered in a muffle furnace at 800 °C for 10 h to obtain KLiNi2Si4O. 10 F2 material.

[0052] (2) Dissolve 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O in deionized water to prepare a solution with a metal ion concentration of 2 mol L. -1 A mixed metal salt solution was prepared, and then, under a nitrogen atmosphere, 4 mol L... -1 NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added concurrently to a continuous stirred tank reactor. The pH of the system solution was maintained within the range of 10-11. The reaction was carried out for 54 hours to obtain Ni. 0.6 Mn 0.2 Co 0.2 (OH)2 precursor slurry.

[0053] (3) Take the 4 mmol KLiNi2Si4O from step (1) 10 F2 material was added to the above 0.1 mol precursor slurry, and the mixture was stirred and reacted for 1 h. After drying at 120 °C for 12 h, 0.104 mol LiOH was mechanically mixed with the synthesized ternary precursor and then placed in a muffle furnace for high-temperature sintering. Further high-temperature sintering at 930 °C for 10 h yielded KLiNi2Si4O. 10 F2@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0054] Example 2

[0055] (1) 16 mmol SiO2, 10 mmol NiO, 2 mmol K2O and 8 mmol NH4F were ball-milled until homogeneous, and then sintered in a muffle furnace at 800 °C for 10 h to obtain KNi. 2.5 Si4O 10 F2 material.

[0056] (2) Dissolve 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O in deionized water to prepare a solution with a metal ion concentration of 2 mol L. -1 A mixed metal salt solution was prepared, and then, under a nitrogen atmosphere, 4 mol L... -1 NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added concurrently to a continuous stirred tank reactor. The pH of the system solution was maintained within the range of 10-11. After reacting for 54 hours, Ni was obtained. 0.6 Mn 0.2 Co 0.2 (OH)2 precursor slurry.

[0057] (3) Take the 4 mmol KNi from step (1) 2.5 Si4O 10 F2 material was added to the above 0.1 mol precursor slurry, and the reaction was continued with stirring for 1 h. After drying at 120 °C for 12 h, 0.104 mol LiOH was mechanically mixed with the synthesized ternary precursor and then sintered in a muffle furnace. The mixture was first pre-calcined at 350 °C for 2 h, and then sintered at 930 °C for 10 h to obtain KNi. 2.5 Si4O 10 F2@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0058] Example 3

[0059] (1) 16 mmol SiO2, 4 mmol NiO, 2 mmol Li2O, 4 mmol MgO, 2 mmol K2O and 8 mmol NH4F were ball-milled until homogeneous, and then sintered in a muffle furnace at 800 °C for 10 h to obtain KLiMgNiSi4O. 10 F2 material.

[0060] (2) Dissolve 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O in deionized water to prepare a solution with a metal ion concentration of 2 mol L. -1 A mixed metal salt solution was prepared, and then, under a nitrogen atmosphere, 4 mol L... -1 NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added concurrently to a continuous stirred tank reactor. The pH of the system solution was maintained within the range of 10-11. After reacting for 54 hours, Ni was obtained. 0.6 Mn 0.2 Co 0.2 (OH)2 precursor slurry.

[0061] (3) Take the 4 mmol KLiMgNiSi4O from step (1) 10 F2 material was added to 0.1 mol of the above precursor slurry, and the mixture was stirred and reacted for 1 hour. After drying at 120°C for 12 hours, 0.104 mol of LiOH was mechanically mixed with the synthesized ternary precursor and then sintered in a muffle furnace. The mixture was pre-calcined at 350°C for 2 hours and then sintered at 930°C for 10 hours to obtain KLiMgNiSi4O. 10 F2@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0062] Example 4

[0063] (2) 16 mmol SiO2, 8 mmol MgO, 2 mmol Li2O, 2 mmol K2O and 8 mmol NH4F were ball-milled until homogeneous, and then sintered in a muffle furnace at 800 °C for 10 h to obtain KLiMg2Si4O. 10 F2 material.

[0064] (3) Dissolve 0.06 mol NiSO4·7H2O, 0.02 mol CoSO4·6H2O and 0.02 mol MnSO4·H2O in deionized water to prepare a solution with a metal ion concentration of 2 mol L. -1 A mixed metal salt solution was prepared, and then, under a nitrogen atmosphere, 4 mol L... -1 NaOH precipitant solution and 20 wt% NH3·H2O complexing agent solution were added concurrently to a continuous stirred tank reactor. The pH of the system solution was maintained within the range of 10-11. The reaction was carried out for 54 hours to obtain Ni. 0.6 Mn 0.2 Co0.2 (OH)2 precursor slurry.

[0065] (4) 4 mmol of KLiMg2Si4O 10 F2 material was added to the above 0.1 mol precursor slurry, and after 1 h of stirring reaction, it was dried at 120°C for 12 h. Then, 0.104 mol of LiOH was mechanically mixed with the above-synthesized ternary precursor, and high-temperature sintering was performed in a muffle furnace. After pre-sintering at 350°C for 2 h, further high-temperature sintering was performed at 930°C for 10 h to obtain KLiMg2Si4O 10 F2@LiNi 0.6 Mn 0.2 Co 0.2 O2.

[0066] The battery assembly was completed by the following method:

[0067] The ternary lithium battery materials obtained in Examples 1-4 and Comparative Examples 1-3 were used as positive electrode materials, and were mixed with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) at a mass ratio of 8:1:1, using N-methyl pyrrolidone (NMP) as a solvent, and stirring in a small beaker at a speed of 800 r / min for 2 h to obtain a slurry. The slurry was coated on a current collector aluminum foil using an automatic coating machine, and was placed on a tempered glass and transferred to a vacuum drying oven at 85°C for drying for 4 h. After punching to prepare a 12 mm diameter electrode sheet, it was dried in a vacuum drying oven at 105°C for 4 h. The water content and oxygen content were both less than 0.1 ppm, and the argon gas atmosphere was filled. The electrode sheet was placed in a glove box for 4 h to reduce the adsorbed water in the transfer process. Then, a CR2032 type button cell was assembled in the glove box. The battery used a pure metal lithium sheet with a diameter of 16 mm and a thickness of 0.5 mm as a negative electrode, and a porous polyethylene film with a model number of Celgard2300 and a diameter of 18 mm as a separator.

[0068] After the battery assembly was completed and aged for 12 h, the charge and discharge test at different potentials was performed. The discharge specific capacity results of the calcined sample after 100 cycles at a current density of 1 C and a voltage of 3-4.3 V are shown in Table 1.

[0069] Table 1

[0070]

[0071] The above only describes the preferred embodiments of the present application. It should be noted that those of ordinary skill in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A precursor for the composite modification of a bi-anionic polymeric silicate nanomaterial, characterized in that it comprises a mixture of a bi-anionic polymeric silicate nanomaterial and a precursor of a metal oxide, said mixture being in the form of a powder. The precursor body and the dianionic polysilicate nanomaterial are compounded on the surface of the precursor body. The double anionic polybasic silicate has a molecular formula of KN x Si4O 10 F2, wherein N is one or more of Li, Ni, and Mg, and x is in a range of 2 to 3; the precursor body has a chemical formula of Ni m Mn n Co 1-m-n (OH)2, wherein m and n are in a range of 0.5≤m≤0.8 and 0.2≤n≤0.

5.

2. A method for preparing a precursor of a dianionic polymeric silicate nanomaterial composite modification according to claim 1, characterized in that, The method comprises the following steps: (1) uniformly mixing a potassium source, a silicon source, a fluorine source and a doping metal source by solid-phase mechanical mixing, and then sintering at high temperature to obtain a dianionic polysilicate nanomaterial; the doping metal is selected from one or more of Li, Ni and Mg; (2) preparing a mixed metal salt solution A of nickel salt, cobalt salt and manganese salt, a precipitant solution and a complexing agent solution; under a protective atmosphere, the mixed metal salt solution A, the precipitant solution and the complexing agent solution are passed into a reactor in parallel to carry out a co-precipitation reaction to obtain a Ni m Mn n Co 1-m-n (OH)2 precursor slurry; (3) adding the dianionic polysilicate nanomaterial to the precursor slurry, continuing to stir for a certain period of time, and then washing and drying the obtained solid after solid-liquid separation.

3. The method of claim 2, wherein the precursor is prepared by the steps of: (a) mixing a source of silicon, a source of alkali metal, and a source of a divalent metal to form a mixture; (b) heating the mixture to form a molten mixture; (c) cooling the molten mixture to form a solid mixture; and (d) milling the solid mixture to form the precursor. In step (1), the silicon source is one or both of silicon dioxide and silicic acid; the potassium source is one or more of potassium oxide, potassium carbonate, potassium nitrate and potassium acetate; the doping metal source is one or more of lithium oxide, nickel oxide, magnesium oxide, lithium carbonate, magnesium carbonate, lithium nitrate, magnesium nitrate, lithium nitrate, lithium acetate and lithium hydroxide, nickel acetate and magnesium acetate; the fluorine source is one or both of NH4HF2 and NH4F.

4. The method for preparing the precursor for the composite modification of bi-anionic multi-component silicate nanomaterials as described in claim 2, characterized in that, In step (1), the molar ratio of potassium in the potassium source to the silicon source, the fluorine source and the doping metal source is 1:4:2: (2-3); in step (3), the molar ratio of the precursor to the dianionic polysilicate is 1: (0.03-0.08).

5. The method for preparing the precursor for the composite modification of bi-anionic multi-component silicate nanomaterials as described in claim 2, characterized in that, In step (1), the sintering temperature is 700-1000°C, and the sintering time is 8-20h.

6. The method for preparing the precursor for the composite modification of bi-anionic multi-component silicate nanomaterials as described in claim 2, characterized in that, In step (2), the manganese salt, the nickel salt and the cobalt salt are one or more of nitrate, acetate and sulfate; the total metal concentration of the mixed metal salt solution is 1-3mol / L; the precipitant solution is a sodium hydroxide solution; the concentration of the precipitant solution is 4-6mol / L; the complexing agent solution is an ammonia solution; the concentration of the ammonia solution is 15-25wt%.

7. The method for preparing the precursor for the composite modification of bi-anionic multi-component silicate nanomaterials as described in claim 2, characterized in that, In step (2), the pH value of the reaction system is controlled to be 10-12 during the co-precipitation process; the co-precipitation reaction time is 30-60h.

8. A modified cathode material, characterized in that, The obtained precursor is mixed with a lithium source and then subjected to two-stage sintering.

9. The modified cathode material of claim 8, wherein, The molar ratio of the precursor to the lithium source is 1: (1.03-1.05); the two-stage sintering comprises low-temperature pre-sintering and high-temperature sintering; the low-temperature pre-sintering temperature is 300-500°C, and the low-temperature pre-sintering time is 1-8h; the high-temperature sintering temperature is 800-1100°C, and the high-temperature sintering time is 10-30h.

10. A lithium-ion battery, characterized by, The modified positive electrode material comprises the modified positive electrode material according to claim 8 or 9.

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