CN114864911A - Modified high-nickel ternary cathode material and preparation method and application thereof - Google Patents
Modified high-nickel ternary cathode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the technical field of preparation of lithium ion battery anode materials, in particular to a modified high-nickel ternary anode material and a preparation method and application thereof. The modified high-nickel ternary positive electrode material is LiNi doped with vanadium x Co (1‑x)/2 Mn (1‑x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) as a matrix, and coating nickel hydroxide gel outside the matrix, and then carrying out high-temperature treatment to obtain the modified high-nickel ternary cathode material. The invention is suitable for high-nickel ternary positive electrode materialLiNi material x Co (1‑x)/2 Mn (1‑x)/ 2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) and modifying with vanadium-containing doped LiNi x Co (1‑x)/2 Mn (1‑x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) as a matrix, then carrying out gel coating by adopting nickel hydroxide, and finally carrying out calcination treatment to obtain the modified high-nickel ternary cathode material so as to overcome the technical defects of poor thermal stability and poor cycle stability of the high-nickel ternary cathode material in the prior art.
Description
Technical Field
The invention belongs to the technical field of preparation of lithium ion battery anode materials, and particularly relates to a modified high-nickel ternary anode material as well as a preparation method and application thereof.
Background
Energy is the key to economic development and social progress, and the establishment of a society supported by sustainable energy is a subject of worldwide attention. With the improvement of the electric endurance mileage requirement of the market, the lithium ion battery is required to have higher energy density, and the anode material is a key factor influencing the energy density of the lithium ion battery. The high-nickel ternary cathode material has the advantages of high specific capacity, good rate capability, relatively low cost and the like, and is considered to be one of the most promising cathode materials of the power lithium ion battery.
The ternary material in the market mainly refers to an oxide consisting of lithium element and transition main group elements of nickel, cobalt and manganese element, and has the advantages of high specific capacity, high cycling stability and high safety performance; because the nickel, the cobalt and the lithium manganese all have alpha-NaFeO 2 The structure is that nickel, cobalt and manganese belong to adjacent elements in the same period, so that eutectic can be well formed, and good synergistic effect among different elements is reflected. The material has larger nickel ion radius, so the increase of the nickel content can increase the values of cell parameters a and c of the material, but can reduce the value of c/a and increase the cell volume, which is beneficial to increasing the lithium ion deintercalation capacity, thereby improving the discharge specific capacity, but because of Ni, the specific capacity of the material is improved 2+ Is difficult to be oxidized into Ni 3+ Thus in the synthesis of LiNiO 2 Part of Ni will be in the anode material 3+ Position is covered with Ni 2+ Due to Li + Radius larger than Ni in lithium layer 2+ Radius and Ni in delithiation 2+ Can be oxidized into Ni with smaller radius 3+ Therefore, a layered collapse structure of the material is caused during lithium deintercalation, a crystal structure is destroyed during charge and discharge, cycle performance is rapidly deteriorated, and excessive nickel also deteriorates thermal stability of the material.
In order to solve the problems of side reaction on the surface of a material, lattice structure degradation, electrolyte decomposition and the like in the charging and discharging processes of a ternary material, a great deal of research is carried out on the modification of the ternary material in the prior art, the main method comprises doping and surface coating, and the purpose of doping is to reduce the content of impuritiesLow cation mixed discharge, improved crystal structure stability and improved Li content + The diffusion coefficient, the transfer impedance are reduced, the reversible capacity and the cycle stability are improved, doping is divided into cation doping, anion doping and multiple ion co-doping, and the cation is doped with Na, Mg, Al, Ti, Nb, Ga and other elements; the anion doping is mainly F doping and PO 3+ Doping, multiple ion codoping mainly has multiple cation codoping and cation and anion codoping.
The ternary material currently commercialized is mainly LiNi 1/3 Co 1/3 Mn 1/3 O 2 However, since the content of the active element Ni is low, the discharge capacity is low, and therefore, a method for modifying the high-nickel lithium ion battery anode material is needed to overcome the technical defects of the high-nickel lithium ion battery anode material.
Disclosure of Invention
Aiming at the technical defects, the invention provides a modified high-nickel ternary cathode material and a preparation method and application thereof, and the invention is used for the high-nickel ternary cathode material LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) and modifying with vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) as a matrix, then carrying out gel coating by adopting nickel hydroxide, and finally carrying out calcination treatment to obtain the modified high-nickel ternary cathode material so as to overcome the technical defects of poor thermal stability and poor cycle stability of the high-nickel ternary cathode material in the prior art.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a modified high-nickel ternary positive electrode material is prepared by doping LiNi with vanadium x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) as a matrix, and coating nickel hydroxide gel outside the matrix, and then carrying out high-temperature treatment to obtain the modified high-nickel ternary cathode material.
The invention also discloses a preparation method of the modified high-nickel ternary cathode material, which comprises the following steps:
(1) preparation of vanadium-containing doped LiNi by sol-gel method x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) a substrate; the materials prepared by the conventional sol-gel method are mixed to reach the molecular level, have good uniformity and are beneficial to controlling the growth speed of particles; after the matrix is doped with vanadium ions, the vanadium ions partially replace the positions of the transition metal ions, more stably occupy the position of the transition metal layer 3a, and have the effect of reducing the mixed arrangement of lithium and nickel cations, so that the crystal structure of the material is stabilized, the structural collapse phenomenon of material lattices in a lithium removal state is inhibited, and the cycle performance is enhanced to a certain extent;
(2) dissolving a nickel source in deionized water to prepare a salt solution, and mixing the accelerant and the vanadium-containing doped LiNi obtained in the step (1) x Co (1-x)/2 Mn (1-x)/2 O 2 Adding the matrix into a salt solution, wherein the molar ratio of the promoter to the nickel ions is 12-24: 1; then crystallizing at the temperature of 150 ℃ and 240 ℃ for 4-12h to obtain a precursor; coating a layer of nickel hydroxide gel on the surface of the vanadium-doped matrix under the hydrothermal crystallization condition of the salt solution and the accelerator;
(3) evaporating the solvent of the precursor obtained in the step (2) to dryness, and then calcining to obtain a modified high-nickel ternary cathode material, wherein the calcining realizes the decomposition of nickel hydroxide to obtain nickel oxide uniformly coated vanadium doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 The coating of the matrix and the nickel oxide can stabilize vanadium-doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 LiNi with internal structure of matrix and capability of preventing vanadium doping x Co (1-x)/2 Mn (1-x)/2 O 2 The surface of the matrix reacts with the electrolyte, so that the safety performance of the material is improved, and the specific capacity and the cycle performance of the material are improved.
Preferably, the nickel source of step (2) is selected from nickel chloride, nickel nitrate or nickel sulfate, and the promoter is selected from triethanolamine or urea.
Preferably, the calcination treatment conditions in step (3) are as follows: raising the temperature to 350-400 ℃ at the speed of 2-10 ℃/min, preserving the heat for 5-8h, and then naturally cooling to room temperature, wherein the condition not only realizes the decomposition of nickel hydroxide gel and the uniform coating, but also avoids the side reaction of the vanadium-doped matrix.
Preferably, the vanadium-containing doped LiNi in the step (1) is x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) the matrix is prepared according to the following steps:
s1, dissolving nickel salt, cobalt salt, manganese salt and a vanadium source in deionized water, stirring for 4-8 hours, dropwise adding citric acid into the deionized water to obtain a mixed solution, stirring the mixed solution at 80-100 ℃ for 12-14 hours for sexual gelation, and drying in an oven until water is completely evaporated to obtain a pretreatment substance;
s2, uniformly mixing the pretreatment substance obtained in the step S1 with a lithium source, sintering for 3h at 500 ℃ of 400- x Co (1-x)/2 Mn (1-x)/2 O 2 A substrate;
wherein the molar ratio of the nickel salt to the cobalt salt to the manganese salt is (6-9): (2-0.5): (2-0.5), wherein the molar ratio of the total amount of the nickel salt, the cobalt salt and the manganese salt to the lithium source and the vanadium source is 1: 1.025-1.05: 0.025-0.05, which is a prior art sol-gel process.
Preferably, the vanadium source of step S1 is selected from ammonium vanadate, and the nickel salt, cobalt salt, and manganese salt are respectively selected from nitrate, sulfate, and acetate thereof.
Preferably, the lithium source of step S2 is selected from lithium nitrate, lithium carbonate or lithium hydroxide.
The invention also protects the lithium ion battery anode piece prepared by the modified high-nickel ternary anode material.
Preferably, the lithium ion battery positive pole piece is prepared according to the following steps:
mixing the modified high-nickel ternary positive electrode material, the binder and the conductive agent, then grinding the mixture in a solvent to form slurry, uniformly coating the slurry on a current collector, and drying the solvent to obtain a positive electrode plate of the lithium ion battery;
the conductive agent is selected from one of Super P conductive carbon black, conductive acetylene black and ordered mesoporous carbon CMK-3;
the binder is selected from one of polyvinylidene fluoride, carboxymethyl cellulose, polyacrylic acid, polytetrafluoroethylene and polyvinyl alcohol;
the mass ratio of the modified high-nickel ternary cathode material to the binder to the conductive agent is 95: 2: 3.
the invention also protects the application of the lithium ion battery anode piece in the preparation of the lithium ion battery, and the lithium ion battery is prepared according to the following steps:
a microporous polyolefin diaphragm and a commercialized LiPF6 electrolyte are adopted, a metal lithium sheet is taken as a negative electrode sheet, and a positive electrode sheet, a diaphragm and a negative electrode sheet of a lithium ion battery are sequentially superposed to assemble the lithium ion battery;
lithium metal is taken as a negative pole piece, and the positive pole piece, the inorganic or polymer solid electrolyte membrane and the negative pole piece of the lithium ion battery are sequentially superposed and then heated and pressurized to assemble the solid lithium battery.
Compared with the prior art, the invention has the beneficial effects that:
1. the prior art shows that the doping of the V element is mainly V 5+ The form of the Li-doped lithium ion battery effectively reduces the phenomena of electron transfer impedance and cation mixed discharging after doping, and leads the Li to be under different multiplying powers + Is easier to de-embed, but due to V 5+ The electrochemical is inactive, and the specific discharge capacity of the doped material for the first time is reduced; the nickel oxide can not only generate reversible electrochemical reaction with Li, but also has high specific capacity and good cycle performance, and still maintains high capacity after repeated cycles, the reaction mechanism of NiO is the redox reaction of NiO and lithium, lithium ions are extracted from a negative electrode during discharging, and are inserted into a positive electrode through electrolyte, at the moment, the positive electrode is in a lithium-rich state, and the lithium reduces NiO to form Ni and Li 2 O, then Ni is oxidized again to generate NiO in the charging process, the oxidation-reduction reaction is a reversible process, and therefore, the nickel oxide is coated on the outer side of the vanadium-doped matrix to effectively solve the problem of V 5+ The first discharge specific capacity of the material is reduced after electrochemical inactive doping.
2. The invention utilizes the coordination of a nickel source and an accelerant to generate a complex, the accelerant is alkaline in aqueous solution, and OH can be generated by electrolysis - With increasing hydrothermal reaction temperatureHigh, reduced coordination, nickel ions and OH - Nickel hydroxide hydrogel generated by the action is evenly coated on the vanadium-doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 The NiO nano-particles are uniformly coated on the vanadium-doped LiNi on the surface of the matrix after calcination x Co (1-x)/2 Mn (1-x)/2 O 2 And the obtained NiO nano-particles have uniform granularity on the outer side of the matrix.
Drawings
FIG. 1 is an SEM image of a modified high-nickel ternary cathode material prepared in example 1 of the present invention;
FIG. 2 is an SEM image of a modified high-nickel ternary cathode material prepared in example 1 of the present invention, and FIG. 2 is a perspective view of FIG. 1;
FIG. 3 is an XRD pattern of a modified high nickel ternary positive electrode material prepared in example 1 of the present invention;
FIG. 4 is an XPS plot of a modified high nickel ternary positive electrode material made in accordance with example 1 of the present invention;
fig. 5 is a performance diagram of a button cell made from the modified high-nickel ternary positive electrode material obtained in example 1 of the present invention and cycled at 0.5C for 1000 cycles.
Detailed Description
The following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention. The experimental methods described in the examples of the present invention are all conventional methods unless otherwise specified.
The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and starting materials are all commercially available unless otherwise specified.
Example 1
A preparation method of a modified high-nickel ternary cathode material comprises the following steps:
(1) vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 (0.6. ltoreq. x. ltoreq.0.9) groupPreparation of the body:
s1, mixing Ni (NO) 3 ) 2 、Co(NO 3 ) 2 、Mn(NO 3 ) 2 Dissolving ammonium vanadate in deionized water, stirring for 6 hours, dropwise adding citric acid into the deionized water to obtain a mixed solution, stirring the mixed solution for 14 hours at 90 ℃ for sexual gelation, and drying in an oven until water is completely evaporated to obtain a pretreatment substance;
wherein, Ni (NO) 3 ) 2 、Co(NO 3 ) 2 、Mn(NO 3 ) 2 In a molar ratio of 6: 2: 2;
s2, uniformly mixing the pre-processed product obtained in the step S1 with lithium nitrate, sintering at 450 ℃ for 3h, preserving heat at 750 ℃ for 12h, and naturally cooling to obtain vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 A substrate;
wherein Ni (NO) 3 ) 2 、Co(NO 3 ) 2 、Mn(NO 3 ) 2 The molar ratio of the total mass to the lithium nitrate and ammonium vanadate was 1: 1.025: 0.025;
(2) dissolving nickel chloride in deionized water to prepare a salt solution, and mixing triethanolamine with the vanadium-containing doped LiNi obtained in the step (1) x Co (1-x)/2 Mn (1-x)/2 O 2 Adding the matrix into a salt solution, wherein the molar ratio of triethanolamine to nickel ions is 12: 1, crystallizing at 240 ℃ for 4h to obtain a precursor;
(3) and (3) drying the precursor in the step (2) to dryness, calcining, heating to 350 ℃ at the speed of 5 ℃/min, and preserving heat for 8 hours to obtain the modified high-nickel ternary cathode material.
Example 2
A preparation method of a modified high-nickel ternary cathode material comprises the following steps:
(1) vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) preparation of a matrix:
s1, mixing NiSO 4 、CoSO 4 、MnSO 4 And ammonium vanadate are dissolved in deionized water and stirred for 4 hours, then citric acid is dropwise added into the mixture to obtain a mixed solution, and the mixed solution is mixedStirring the solution at 80 ℃ for 13h for sexual gelation, and drying in an oven until water is completely evaporated to obtain a pretreatment substance;
wherein, NiSO 4 、CoSO 4 、MnSO 4 In a molar ratio of 8: 1: 1;
s2, uniformly mixing the pre-processed product obtained in the step S1 with lithium carbonate, sintering at 400 ℃ for 3h, preserving heat at 800 ℃ for 10h, and naturally cooling to obtain vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 A substrate;
wherein, NiSO 4 、CoSO 4 、MnSO 4 The molar ratio of the total mass to the lithium carbonate and ammonium vanadate is 1: 1.04: 0.04;
(2) dissolving nickel chloride in deionized water to prepare a salt solution, and mixing triethanolamine with the vanadium-containing doped LiNi obtained in the step (1) x Co (1-x)/2 Mn (1-x)/2 O 2 Adding the matrix into a salt solution, wherein the molar ratio of triethanolamine to nickel ions is 18: 1, crystallizing at 200 ℃ for 8 hours to obtain a precursor;
(3) and (3) drying the precursor in the step (2) to dryness, calcining, heating to 400 ℃ at the speed of 10 ℃/min, and preserving heat for 6 hours to obtain the modified high-nickel ternary cathode material.
Example 3
A preparation method of a modified high-nickel ternary cathode material comprises the following steps:
(1) vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) preparation of a matrix:
s1, mixing Ni (CH) 3 COO) 2 、Co(CH 3 COO) 2 、Mn(CH 3 COO) 2 Dissolving ammonium vanadate in deionized water, stirring for 8 hours, dropwise adding citric acid into the deionized water to obtain a mixed solution, stirring the mixed solution at 100 ℃ for 12 hours, and drying the mixed solution in an oven until water is completely evaporated to obtain a pretreatment substance;
wherein, Ni (CH) 3 COO) 2 、Co(CH 3 COO) 2 、Mn(CH 3 COO) 2 In a molar ratio of 9: 0.5: 0.5;
s2, uniformly mixing the pre-processed product obtained in the step S1 with lithium nitrate, sintering at 500 ℃ for 3h, preserving heat at 700 ℃ for 14h, and naturally cooling to obtain vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 A base;
wherein, Ni (CH) 3 COO) 2 、Co(CH 3 COO) 2 、Mn(CH 3 COO) 2 The molar ratio of the total mass to the lithium nitrate and ammonium vanadate was 1: 1.05: 0.05;
(2) dissolving nickel nitrate in deionized water to prepare a salt solution, and mixing triethanolamine with the vanadium-containing doped LiNi obtained in the step (1) x Co (1-x)/2 Mn (1-x)/2 O 2 Adding the matrix into a salt solution, wherein the molar ratio of triethanolamine to nickel ions is 24: 1, crystallizing at 150 ℃ for 12 hours to obtain a precursor;
(3) and (3) drying the precursor in the step (2) to dryness, calcining, heating to 400 ℃ at the speed of 2 ℃/min, and preserving heat for 5 hours to obtain the modified high-nickel ternary cathode material.
The properties and effects of the modified high-nickel ternary positive electrode materials prepared in the embodiments 1 to 3 of the invention are similar, and the following studies are carried out by taking the embodiment 1 as an example, and the specific study methods and results are as follows:
preparing a positive pole piece of the lithium ion battery:
mixing the modified high-nickel ternary positive electrode material prepared in the embodiment 1, a binder polyvinylidene fluoride and a conductive agent acetylene black, then grinding the mixture in N-methyl pyrrolidone until slurry is formed, uniformly coating the slurry on a current collector copper foil, and drying a solvent to obtain a lithium ion battery positive electrode piece;
the modified high-nickel ternary cathode material, the binder and the conductive agent are mixed according to a mass ratio of 95: 2: 3;
preparation of lithium ion solid state battery:
lithium metal is used as a negative pole piece, and the positive pole piece, the polymer solid electrolyte membrane and the negative pole piece of the lithium ion battery are sequentially superposed and then heated and pressurized to assemble the solid lithium battery.
The modified high-nickel ternary cathode material and the lithium ion solid-state battery are researched, and the results are shown in fig. 1-5:
FIGS. 1 and 2 are SEM images of the modified high-nickel ternary cathode material prepared in example 1, and FIG. 2 is a perspective view of FIG. 1, and it can be seen from FIGS. 1 and 2 that after coating and sintering, the prepared electrode material sample mainly consists of spherical materials with diameters of 1-10 μm, and nickel oxide is uniformly coated and dispersed in vanadium-containing doped LiNi x Co (1-x)/2 Mn (1-x)/2 O 2 The surface of the substrate.
The results of FIG. 3 show that the modified high-nickel ternary cathode material and PDF card LiNiO prepared by the invention 2 (PDF #85-1966) and no impure phase was formed, indicating that stable NiO was achieved 2 And (4) coating.
The results of FIG. 4 show that the characteristic peaks of vanadium and nickel can be seen in the XPS full spectrum of the modified high-nickel ternary cathode material prepared by the invention, which indicates that stable vanadium doping and NiO are realized 2 And (4) coating.
Fig. 5 is a graph of reversible capacity of a button cell prepared from the modified high-nickel ternary cathode material of example 1 of the present invention after 1000 cycles at 0.5C, and the results of fig. 5 show that the capacity retention rate is 90% or more after 500 cycles and 80% or more after 1000 cycles, which indicates that a lithium ion battery prepared from the modified high-nickel ternary cathode material has excellent cycle stability after modification.
The button cell is prepared from the modified high-nickel ternary positive electrode materials prepared in the embodiments 1 to 3, and the capacity retention rates of the button cell are respectively compared and researched at 25 ℃ and 45 ℃ for 1000 times of charging and discharging at 0.5C, and the research results are shown in Table 1:
TABLE 1 comparison table of the retention rate of the circulating capacity at different temperatures
The data in table 1 show that after charging and discharging at 25 ℃ and 45 ℃, respectively, the capacity retention rate at 45 ℃ is lower than 25 ℃, but in contrast, the difference between the capacity retention rate and the capacity retention rate is not large, and the capacity retention rate at 45 ℃ can reach 80.1% at most, which indicates that the modified high-nickel ternary cathode material prepared after modification has excellent thermal stability.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. The modified high-nickel ternary cathode material is characterized in that the modified high-nickel ternary cathode material is LiNi doped with vanadium x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) as a matrix, and coating nickel hydroxide gel outside the matrix, and then carrying out high-temperature treatment to obtain the modified high-nickel ternary cathode material.
2. The preparation method of the modified high-nickel ternary cathode material according to claim 1, characterized by comprising the following steps:
(1) preparation of vanadium-containing doped LiNi by sol-gel method x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) a substrate;
(2) dissolving a nickel source in deionized water to prepare a salt solution, and mixing the accelerant and the vanadium-containing doped LiNi obtained in the step (1) x Co (1-x)/2 Mn (1-x)/2 O 2 Adding the matrix into a salt solution, and then crystallizing at the temperature of 150 ℃ and 240 ℃ for 4-12h to obtain a precursor;
(3) and (3) calcining the precursor obtained in the step (2) to obtain the modified high-nickel ternary cathode material.
3. The preparation method of the modified high-nickel ternary cathode material as claimed in claim 2, wherein the nickel source in step (2) is selected from nickel chloride, nickel nitrate or nickel sulfate, and the promoter is selected from triethanolamine or urea.
4. The preparation method of the modified high-nickel ternary cathode material as claimed in claim 2, wherein the calcination treatment conditions in the step (3) are as follows: raising the temperature to 350-400 ℃ at the speed of 2-10 ℃/min, preserving the temperature for 5-8h, and naturally cooling to the room temperature.
5. The method for preparing the modified high-nickel ternary cathode material as claimed in claim 2, wherein the vanadium-doped LiNi in the step (1) is x Co (1-x)/2 Mn (1-x)/2 O 2 (x is more than or equal to 0.6 and less than or equal to 0.9) the matrix is prepared according to the following steps:
s1, dissolving nickel salt, cobalt salt, manganese salt and a vanadium source in deionized water, stirring for 4-8 hours, dropwise adding citric acid into the deionized water to obtain a mixed solution, stirring the mixed solution at 80-100 ℃ for 12-14 hours for sexual gelation, and drying in an oven until water is completely evaporated to obtain a pretreatment substance;
s2, uniformly mixing the pretreatment substance obtained in the step S1 with a lithium source, sintering for 3h at 500 ℃ of 400- x Co (1-x)/2 Mn (1-x)/2 O 2 A substrate;
wherein the molar ratio of the nickel salt to the cobalt salt to the manganese salt is (6-9): (2-0.5): (2-0.5), wherein the molar ratio of the total amount of the nickel salt, the cobalt salt and the manganese salt to the lithium source and the vanadium source is 1: 1.025-1.05: 0.025-0.05.
6. The method as claimed in claim 5, wherein the vanadium source in step S1 is selected from ammonium vanadate, and the nickel salt, cobalt salt, and manganese salt are respectively selected from nitrate, sulfate, and acetate.
7. The method as claimed in claim 5, wherein the lithium source in step S2 is selected from lithium nitrate, lithium carbonate or lithium hydroxide.
8. A lithium ion battery positive pole piece prepared by using the modified high-nickel ternary positive pole material of claim 1.
9. The application of claim 8, wherein the lithium ion battery positive pole piece is prepared according to the following steps:
mixing the modified high-nickel ternary positive electrode material, the binder and the conductive agent, then grinding the mixture in a solvent to form slurry, uniformly coating the slurry on a current collector, and drying the solvent to obtain a positive electrode plate of the lithium ion battery;
the conductive agent is selected from one of Super P conductive carbon black, conductive acetylene black and ordered mesoporous carbon CMK-3;
the binder is selected from one of polyvinylidene fluoride, carboxymethyl cellulose, polyacrylic acid, polytetrafluoroethylene and polyvinyl alcohol;
the mass ratio of the modified high-nickel ternary cathode material to the binder to the conductive agent is 95: 2: 3.
10. the application of the lithium ion battery positive pole piece of claim 9 in the preparation of a lithium ion battery, wherein the lithium ion battery is prepared according to the following steps:
using microporous polyolefin separator, commercial LiPF 6 The electrolyte is prepared by stacking a positive pole piece, a diaphragm and a negative pole piece of the lithium ion battery in sequence by taking a metal lithium piece as a negative pole piece, and assembling the positive pole piece, the diaphragm and the negative pole piece into the lithium ion battery;
lithium metal is taken as a negative pole piece, and the positive pole piece, the inorganic or polymer solid electrolyte membrane and the negative pole piece of the lithium ion battery are sequentially superposed and then heated and pressurized to assemble the solid lithium battery.
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