A ternary cathode material for lithium-ion batteries and its preparation method

Abstract

The present invention discloses a lithium ion battery ternary positive electrode material, wherein the material is a LiNi x Co y Mn 1‑x‑y A new phase is introduced into the O2 ternary positive electrode material, wherein 0<x<1, 0<y<1; the new phase is a metal oxide, and the new phase is x Co y Mn 1‑x‑y The coherent growth of the lamellar phase in the O2 ternary cathode material. The coherent growth of the two phases in the present invention is achieved by regulating the ternary cathode material components and process parameters during the material synthesis process, thereby inducing a new phase that coexists with the lamellar phase within the bulk phase of the ternary cathode material particles. The coherent growth of the lamellar phase and the new phase within the bulk phase of the ternary cathode particles acts as a "pinning" force within the crystal, preventing crystal structure collapse caused by anisotropic volume changes during charge and discharge, thereby alleviating mechanical failure of the ternary cathode material during cycling.

Description

Technical Field

[0001] The invention relates to the field of lithium ion battery material preparation, and discloses a lithium ion battery ternary positive electrode material and a preparation method thereof. Background Art

[0002] Since the 21st century, new energy electric vehicles have gradually entered people's daily lives. Lithium-ion batteries have successfully occupied the electric vehicle application market due to their advantages in energy density and life. In order to increase the service life and cruising range of electric vehicles, high-capacity ternary positive electrode materials are being widely used and studied. However, the application of ternary positive electrode materials in high-energy-density lithium-ion batteries also faces a series of problems. Among them, the anisotropic volume changes accompanied by the release and insertion of lithium ions in the ternary positive electrode material during the charging and discharging process will cause intracrystalline cracks and even particle breakage in the positive electrode material, ultimately causing serious degradation of electrochemical performance. Surface coating and element doping process routes are often used to alleviate the mechanical failure problem of ternary positive electrode materials. CN113363478A discloses a commercial lithium-containing compound Li4Ti5O 12 Coated ternary positive electrode material. CN109742336A discloses a W-doped ternary positive electrode material. Modifying the ternary positive electrode material through surface coating and element doping processes can suppress mechanical failure problems and improve electrochemical stability, but the surface coating layer and doping elements cannot solve the repeated anisotropic volume changes within the particles during long cycles. In view of this, it is indeed necessary to provide a simple method to introduce a coherently grown electrochemically inert crystalline phase into the bulk phase of the ternary positive electrode material to stabilize the structure and extend the battery life. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention provides a lithium-ion battery ternary cathode material and a preparation method thereof, wherein the method is based on the two-phase coherent growth of a stable ternary cathode material.

[0004] The technical solution adopted in the present invention is as follows:

[0005] A lithium-ion battery ternary cathode material is a material that stabilizes the material structure by inducing the generation of a new phase of coherent growth within the bulk of the ternary cathode material. The components of the ternary cathode material are LiNi x Co y Mn 1-x-y O2, wherein 0<x<1, 0<y<1; the new phase of the coherent growth is a metal oxide, and further, the composition of the new phase is M x O yWhen the component is LiM2O4, M is one or more of Ni, La, Sr, Y, Zr, Ti, and Nb, and x and y must satisfy valence equilibrium; when the component is LiM2O4, M is one or more of Ni, Co, and Mn; when the component is LiMO3, M is one or more of Sr, Ti, Sn, Zr, Nb, Ta, W, and La; when the component is A4[LiM]O8, A is one or more of Ti, Sn, Zr, Nb, Ta, W, and La; and M is one or more of Mn, Co, Ni, Ti, Sn, Sr, Zr, Ta, and W. The crystal structure of the coherently grown new phase is one of a spinel structure, a perovskite structure, or a rock salt structure.

[0006] The co-growth of two phases in the present invention is achieved by regulating the ternary cathode material components and process parameters during the material synthesis process, inducing a new phase that co-exists with the lamellar phase within the bulk phase of the ternary cathode material. The lamellar phase and the new phase co-grow within the bulk phase of the ternary cathode particles. The new phase acts as a "pinning" force within the crystal, preventing crystal structure collapse caused by anisotropic volume changes during charge and discharge, thereby alleviating mechanical failure of the ternary cathode material during cycling.

[0007] "Coherence" means that the atoms at the interface are simultaneously located at the nodes of the two-phase lattices, that is, the lattices of the two phases are connected to each other, and the atoms at the interface are shared by both. This patent introduces a small amount of new phase into the main layered ternary material. This new phase grows coherently with the main layered structure, acting as a "pinning" within the material, greatly limiting the stress changes in the ternary material during the lithium insertion and deintercalation process. This solves the problem of ternary material particle fragmentation for the first time through the "coherent growth" method.

[0008] Specifically, the method for preparing the two-phase coherently grown ternary cathode material of the present invention comprises:

[0009] The first step is the precursor preparation, where a ternary co-precipitation reactor is used. A transition metal salt solution of a certain concentration is prepared according to the ratio of Ni, Co, and Mn elements, and a new phase metal salt solution of a certain concentration is also prepared. The above two solutions are mixed in a specific ratio. A certain concentration of sodium hydroxide and ammonia solution is used to adjust the pH value of the reaction system. Using a ternary co-precipitation reactor, deionized water is added to the bottom of the reactor as the base liquid, and the salt solution is added to the reactor body through a peristaltic pump. At the same time, alkali solution and ammonia solution are added to maintain a stable pH value, and the temperature of the reactor body is controlled by a constant temperature water area. Nitrogen is used as a protective gas throughout the reaction process, and the stirring speed is controlled at the same time. After the salt solution is completely added to the reactor body, stirring is continued and an aging step is performed after the reaction is completed. The reaction product is repeatedly washed with deionized water and ethanol and then dried under vacuum conditions to obtain a precursor powder; the precursor powder is post-treated to achieve two-phase coherent growth to obtain a lithium-ion battery ternary positive electrode material. The key to post-treatment is to control the calcination process. Specifically, the following post-treatment processes can be used:

[0010] The first method is to mix the precursor powder with an appropriate amount of lithium salt, and then perform a heat treatment process 1 in a pure oxygen atmosphere to obtain a ternary positive electrode material in which a new phase of coherent growth is a rock salt structure.

[0011] The second method is to not add the new phase metal salt solution during the precursor powder preparation process, but only add the transition metal salt solution to the ternary co-precipitation reactor, mix the precursor powder with an appropriate amount of lithium salt, control the molar ratio of lithium to transition metal to be less than 1, and undergo heat treatment process 2 in a pure oxygen atmosphere to obtain a ternary cathode material with a coherent growth new phase of spinel structure;

[0012] The third method is to subject the precursor powder to heat treatment process 3 to obtain an oxide precursor material, mix it with an appropriate amount of lithium salt, and then subject it to heat treatment process 4 in a pure oxygen atmosphere to obtain a ternary cathode material with a coherent growth phase and a perovskite structure.

[0013] Among them, the heat treatment process 1 is a three-stage high-temperature heat treatment, wherein the first stage is a heat treatment at a temperature of 300-600°C for 3-6 hours, the second stage is a heat treatment at a temperature of 700-850°C for 6-10 hours, and the third stage is a heat treatment at a temperature of 900-950°C for 4-6 hours, and then cooled with the furnace.

[0014] The heat treatment process 2 is a two-stage high-temperature heat treatment, wherein the first stage is a heat treatment at a temperature of 300-600°C for 3-6 hours, and the second stage is a heat treatment at a temperature of 700-950°C for 8-20 hours, followed by cooling with the furnace.

[0015] The heat treatment process 3 is as follows: heat treatment temperature of 400-650° C., heat treatment time of 3-8 hours, and then cooling with the furnace.

[0016] The heat treatment process 4 is a two-stage high-temperature heat treatment, wherein the first stage is a heat treatment at 300-600°C for 3-6 hours, and the second stage is a heat treatment at 700-950°C for 8-20 hours, and finally the cooling rate is set to 1-3°C / min.

[0017] As a preferred technical solution, the mass percentage of the new phase coherently grown in the present invention is w, of which 0.1% <w<5%。

[0018] The alkali solution described in the present invention can be sodium hydroxide solution.

[0019] The lithium salt is usually one of lithium carbonate, lithium hydroxide, lithium chloride and lithium sulfate.

[0020] Compared with the previous technology, the present invention has the following beneficial effects:

[0021] A simple method was used to obtain a structurally stable ternary cathode material, in which the layered phase and the new phase coherently grow. During charge and discharge, lithium ions are released and inserted into the layered phase, accompanied by repeated anisotropic volume changes. The coherently grown new phase pins the layered phase, thus supporting it and preventing structural collapse. Due to the pinning effect of the new phase, this modified ternary cathode material can maintain a stable crystal structure under high voltage and long cycling conditions without mechanical particle failure, thereby achieving excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 .X-ray diffraction pattern of La2O3 coherently grown ternary cathode material;

[0023] Figure 2 Scanning electron microscope image of La2O3 coherently grown ternary cathode material;

[0024] Figure 3 Transmission electron micrograph of a coherently grown La2O3 ternary cathode material. The disordered phase is the La2O3 phase, and the layered phase is a layered phase.

[0025] Figure 4 Cycling performance of the original NCM811 sample and the modified NCM811-La2O3 sample at a current density of 40 mAh / g;

[0026] Figure 5 .X-ray transmission micrographs of the original NCM811 sample and the modified sample NCM811-La2O3 after 50 cycles at a current density of 40 mAh / g.

[0027] Figure 6.X-ray diffraction pattern of LiMn2O4 coherently grown ternary cathode material;

[0028] Figure 7 Cycling performance of the original NCM811 sample and the modified NCM811-LiMn2O4 sample at a current density of 40 mAh / g;

[0029] Figure 8 X-ray diffraction pattern of La4[LiMn]O8 coherently grown ternary cathode material;

[0030] Figure 9 Transmission electron microscopy image of La4[LiMn]O8 coherently grown ternary cathode material;

[0031] Figure 10 Cycling performance of the original NCM811 sample and the modified NCM811-La4[LiMn]O8 sample at a current density of 40 mAh / g;

[0032] Figure 11 .X-ray diffraction pattern of SrTiO3 coherently grown ternary cathode material;

[0033] Figure 12 Cycling performance of the original NCM811 sample and the modified NCM811-SrTiO3 sample at a current density of 40 mAh / g; DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1: La2O3 coherent growth stable ternary cathode material, prepared by the following steps:

[0036] (1) Prepare solution a of three sulfates of Ni, Co, and Mn at a molar ratio of 8:1:1, and prepare solution b of sulfate of La. The concentrations of solutions a and b are both 2 mol / L, and solutions a and b are mixed at a volume ratio of 25:1. In addition, prepare 2 mol / L sodium hydroxide solution and 1 mol / L ammonia solution. First, use a metering pump to pump the mixed solution into the reactor at a flow rate of 15 L / h, and at the same time add sodium hydroxide and ammonia solution into the reactor, and control the pH value of the reaction system to be 11. Maintain a nitrogen atmosphere during the reaction, and keep the reactor temperature at 60 ° C and the stirring speed at 550 rpm / min. After the reaction liquid is completely consumed, continue stirring for 2 h, and finally age with the reactor for 24 h. The precursor product obtained by repeatedly washing the reaction product with deionized water is then transferred to an 80 ° C vacuum oven for thorough drying. The resulting precursor is a hydroxide of a metal element;

[0037] (2) Weigh 10 g of precursor powder and 4.77 g of lithium hydroxide monohydrate, mix them manually in a mortar for 20 min, and then transfer them to an alumina crucible;

[0038] (3) Under pure oxygen atmosphere, the gas flow rate is controlled at 10 ml / min, the heating rate is 3 °C / min, and the calcination is carried out at 500 °C for 4 hours, then the temperature is increased to 750 °C, and the calcination is continued for 12 hours, and finally the calcination is carried out at 920 °C for 4 hours, and then the furnace is cooled.

[0039] (4) The calcined powder was ground and dispersed, and then passed through a 300-mesh sieve and named NCM811-La2O3;

[0040] In order to study the effect of the rock salt phase coherent growth modification method on the crystal structure of the ternary cathode material, the modified cathode material was characterized by X-ray diffraction (XRD), such as Figure 1 As shown, a small amount of La2O3 phase can be obtained by introducing the metal element La into the precursor preparation process. Figure 2 This is the scanning electron microscope (SEM) of the modified ternary cathode material, showing the micron-scale secondary spherical particle morphology. Figure 3 This is the transmission electron microscopy (TEM) result of the modified positive electrode material, in which the coherently grown La2O3 phase and layered phase can be clearly observed. Figure 4 The cyclic performance test of the ternary cathode material before and after modification is shown in Figure 2. The original material LiNi was used without modification using the same method. 0.8 Co 0.1 Mn 0.1 The first discharge specific capacity of O2 (NCM811) is 185mAh / g, while the first discharge specific capacity of NCM811-La2O3 prepared in this example is 180mAh / g. After 50 cycles, the remaining capacity of NCM811 is 134mAh / g, and the capacity retention rate is 72.4%. In contrast, NCM811-La2O3 can still obtain 161mAh / g after 50 cycles, and the capacity retention rate is 89.6%. The results of electrochemical tests show that the introduction of the new phase La2O3 grown coherently can significantly improve the electrochemical performance of the ternary positive electrode material. Figure 5 The X-ray transmission photographs of the original material and the modified material after 50 cycles are shown. It can be clearly seen that the original sample particles are severely broken, while the modified sample particles maintain a complete mechanical structure with only a few cracks.

[0041] Example 2: A spinel structure coherently grown stable ternary cathode material is prepared by the following steps:

[0042] (1) Prepare a solution of three sulfates of Ni, Co, and Mn in a molar ratio of 8:1:1, with a solution concentration of 2 mol / L. In addition, prepare a 2 mol / L sodium hydroxide solution and a 1 mol / L ammonia solution. First, use a metering pump to pump the transition metal solution into the reactor at a flow rate of 15 L / h, and at the same time add sodium hydroxide and ammonia solution to the reactor to control the pH value to 11. Maintain a nitrogen atmosphere during the reaction, and keep the reactor temperature at 60 ° C and the stirring speed at 550 rpm / min. After the reaction liquid is completely consumed, continue stirring for 2 hours, and finally age with the reactor for 24 hours. The precursor powder obtained after repeatedly washing the reaction product with deionized water is then transferred to an 80 ° C vacuum oven for thorough drying.

[0043] (2) Weigh 10 g of precursor powder and mix it with 4.45 g (lithium content is less than 1) lithium hydroxide monohydrate, grind it manually for 15 min, and then transfer it to an alumina crucible;

[0044] (3) In a pure oxygen atmosphere, the gas flow rate was controlled at 10 ml / min, the heating rate was 3 °C / min, and the calcination was carried out at 500 °C for 4 h, then the temperature was raised to 750 °C, and the calcination was continued for 12 h, and finally the furnace was cooled;

[0045] In order to study the effect of spinel phase coherent growth modification method on the crystal structure of ternary cathode materials, XRD test was carried out on the modified cathode materials, such as Figure 6 As shown, in this example, no additional new phase components were added in step (1). Instead, by controlling the molar ratio of Li and transition metal to be less than 1, a small amount of spinel phase LiMn2O4 appeared in the sample obtained by high temperature calcination. Figure 7 This is a cyclic test of the ternary positive electrode material before and after modification. The original material NCM811 has a first discharge specific capacity of 185mAh / g, while the first discharge specific capacity of NCM811-LiMn2O4 prepared in this example is 182.5mAh / g. After 50 cycles, the remaining capacity of NCM811 is 134mAh / g, and the capacity retention rate is 72.4%. In contrast, NCM811-LiMn2O4 can still obtain 169.2mAh / g after 50 cycles, and the capacity retention rate is 92.7%. The results of electrochemical tests show that the introduction of coherently grown spinel phase LiMn2O4 can significantly improve the stability of the ternary positive electrode material.

[0046] Example 3: La4[LiMn]O8 coherent growth stable ternary cathode material, the preparation method is as follows

[0047] (1) Prepare solution a of three sulfates of Ni, Co, and Mn in a molar ratio of 8:1:1, and prepare solution b of La sulfate. The concentrations of solution a and b are both 2 mol / L, and the solutions a and b are mixed in a volume ratio of 20:1. In addition, prepare 2 mol / L sodium hydroxide solution and 1.5 mol / L ammonia solution. First, use a metering pump to pump the transition metal solution into the reactor at a flow rate of 10 L / h, and at the same time add sodium hydroxide and ammonia solution to the reactor, and control the pH value to 11.5. Maintain a nitrogen atmosphere during the reaction, and keep the reactor temperature at 60 ° C and the stirring speed at 550 rpm / min. After the reaction solution is completely consumed, continue stirring for 2 h, and finally age in the reactor for 24 h. The hydroxide precursor powder obtained by repeatedly washing the reaction product with deionized water is then transferred to an 80 ° C vacuum oven for thorough drying.

[0048] (2) calcining the hydroxide precursor powder at 500°C for 5 h to obtain oxide powder;

[0049] (3) Weigh 3 g of oxide powder and 1.65 g of lithium hydroxide monohydrate, mix them manually in a mortar for 20 min, and then transfer them to an alumina crucible.

[0050] (4) Under pure oxygen atmosphere, the gas flow rate is controlled at 10 ml / min, the heating rate is 3 °C / min, calcined at 450 °C for 5 hours, then treated at 920 °C for 12 hours, and finally cooled naturally to room temperature in the furnace.

[0051] In order to study the effect of La4[LiMn]O8 coherent growth modification method on the crystal structure of ternary cathode materials, XRD tests were performed on the modified cathode materials, such as Figure 8 As shown in Figure 1, a small amount of perovskite structure La4[LiMn]O8 was obtained by introducing La element and rationally controlling the co-precipitation and calcination process. Figure 9 As shown in A, the perovskite structure La4[LiMn]O8 phase and the layered phase are combined in a lattice symbiotic manner, and the two phases are compatible with each other; Figure 9 B is the corresponding fast Fourier transform spectrum, where the diffraction spots (014, 011, 003) of the layered structure and the diffraction spots (011) of the perovskite structure coexist. Figure 9 C is a local magnified image of the La4[LiMn]O8 atomic phase of the perovskite structure, in which small balls of different sizes are used to mark the atomic occupancy. Figure 10This is a test of the cyclic performance of the ternary positive electrode materials before and after modification. The original material NCM811, which was produced using the same method but without modification, had a first discharge capacity of 185 mAh / g, while the NCM811-La4[LiMn]O8 produced in this example had a first discharge capacity of 182 mAh / g. After 50 cycles, the remaining capacity of NCM811 was 134 mAh / g, with a capacity retention rate of 72.4%. In contrast, NCM811-La4[LiMn]O8 still achieved 169 mAh / g after 50 cycles, with a capacity retention rate of 92.8%. The results of electrochemical tests show that the introduction of the coherently grown perovskite structure La4[LiMn]O8 can significantly improve the stability of the ternary positive electrode material.

[0052] Example 4: Perovskite phase coherent growth stable ternary cathode material, the preparation method is as follows

[0053] (3) Prepare solution a of three sulfates of Ni, Co, and Mn in a molar ratio of 8:1:1, and prepare a mixed sulfate solution of Sr and Ti. The concentrations of solutions a and b are both 2 mol / L, and the solutions a and b are mixed in a volume ratio of 30:1. In addition, prepare a 2 mol / L sodium hydroxide solution and a 1 mol / L ammonia solution. First, use a metering pump to pump the transition metal solution into the reactor at a flow rate of 15 L / h, and at the same time add sodium hydroxide and ammonia solution to the reactor, and control the pH value to 11. Maintain a nitrogen atmosphere during the reaction, and keep the reactor temperature at 60 ° C and the stirring speed at 550 rpm / min. After the reaction solution is completely consumed, continue stirring for 2 h, and finally age in the reactor for 24 h. The hydroxide precursor powder obtained by repeatedly washing the reaction product with deionized water is then transferred to an 80 ° C vacuum oven for thorough drying.

[0054] (4) calcining the hydroxide precursor powder at 500°C for 5 h to obtain oxide powder;

[0055] (3) Weigh 3 g of oxide powder and 1.6 g of lithium hydroxide monohydrate, mix them manually in a mortar for 20 min, and then transfer them to an alumina crucible.

[0056] (4) Under pure oxygen atmosphere, the gas flow rate was controlled at 10 ml / min, the heating rate was 3 °C / min, calcined at 350 °C for 5 h, then treated at 890 °C for 15 h, and finally cooled to room temperature at a cooling rate of 1.5 °C / min.

[0057] In order to study the effect of the coherent growth modification method of the perovskite structure on the crystal structure of the ternary cathode material, XRD tests were performed on the modified cathode material, such as Figure 11 As shown, by introducing Sr and Ti elements, a small amount of perovskite structure SrTiO3 was obtained through high-temperature calcination. Figure 12 This is a test of the cyclic performance of the ternary positive electrode materials before and after modification. The original material NCM811, which was produced using the same method but without modification, had a first discharge capacity of 185 mAh / g, while the NCM811-SrTiO3 produced in this example had a first discharge capacity of 182 mAh / g. After 50 cycles, the remaining capacity of NCM811 was 134 mAh / g, with a capacity retention rate of 72.4%. In contrast, NCM811-SrTiO3 can still obtain 163 mAh / g after 50 cycles, with a capacity retention rate of 89.6%. The results of electrochemical tests show that the introduction of coherently grown perovskite structure SrTiO3 can improve the stability of the ternary positive electrode material.

[0058] The above methods can all prepare two-phase coherently grown ternary cathode materials, which can effectively stabilize the crystal structure of the ternary cathode materials and thus obtain improved electrochemical performance.

[0059] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a ternary positive electrode material for a lithium ion battery, characterized in that: The material is LiNi x Co y Mn 1-x-y A new phase is introduced into the O2 ternary positive electrode material, wherein 0<x<1, 0<y<1; the new phase is a metal oxide, and the new phase is x Co y Mn 1-x-y Coherent growth of layered phases in O2 ternary cathode materials; The preparation method comprises: preparing a transition metal salt solution according to the ratio of Ni, Co and Mn elements in the main phase of the ternary positive electrode material, preparing a new phase metal salt solution according to the ratio of metal elements in the new phase, and mixing the above two solutions to obtain a salt solution; using a ternary coprecipitation reactor, adding deionized water as a bottom liquid at the bottom of the reactor, adding the salt solution into the reactor body through a peristaltic pump, and adding alkali solution and ammonia water to maintain a stable pH value, controlling the temperature of the reactor body through a constant temperature water bath, using nitrogen as a protective gas during the entire reaction process, and controlling the stirring speed at the same time, and continuing to stir after all the salt solution is added to the reactor body, and aging after the reaction is completed, and then repeatedly washing the reaction product with deionized water and ethanol and drying it under vacuum conditions to obtain a precursor powder; performing post-treatment on the precursor powder to achieve two-phase coherent growth; the post-treatment process is as follows: mixing the obtained precursor powder with a lithium salt, and performing a heat treatment process 1 under a pure oxygen atmosphere to obtain a lithium-ion battery ternary positive electrode material, wherein the coherent growth The new phase grown is a rock salt structure; the heat treatment process 1 is a three-stage high-temperature heat treatment, wherein the first stage is a heat treatment at a temperature of 300-600°C for 3-6 hours, the second stage is a heat treatment at a temperature of 700-850°C for 6-10 hours, and the third stage is a heat treatment at a temperature of 900-950°C for 4-6 hours, followed by furnace cooling; or the post-treatment process is as follows: the precursor powder is subjected to a heat treatment process 3 to obtain an oxide precursor material, which is mixed with a lithium salt, and subjected to a heat treatment process 4 in a pure oxygen atmosphere to obtain a lithium-ion battery ternary positive electrode material, wherein the coherently grown new phase is a perovskite structure; the heat treatment process 3 is: a heat treatment temperature of 400-650°C, a heat treatment time of 3-8 hours, and then furnace cooling; the heat treatment process 4 is a two-stage high-temperature heat treatment, wherein the first stage is a heat treatment at a temperature of 300-600°C for 3-6 hours, the second stage is a heat treatment at a temperature of 700-950°C for 8-20 hours, and finally the cooling rate is set to 1-3°C / min.

2. The preparation method according to claim 1, characterized in that The new phase is M x O y , wherein M is one or more of Ni, La, Sr, Y, Zr, Ti, and Nb, and x and y must satisfy valence balance.

3. The preparation method according to claim 1, characterized in that The new phase is A4[LiM]O8, wherein A is one or more of Ti, Sn, Zr, Nb, Ta, W, and La; and M is one or more of Mn, Co, Ni, Ti, Sn, Sr, Zr, Ta, and W.

4. The preparation method according to claim 1, characterized in that The new phase and the LiNi x Co y Mn 1-x-y The mass percentage of O2 ternary positive electrode material is w, and meets 0.1% <w<5%。

Images