Ternary positive electrode material, preparation method thereof, positive electrode and battery

Abstract

The invention relates to the technical field of battery materials, and discloses a ternary positive electrode material, a preparation method thereof, a positive electrode and a battery. The preparation method provided by the invention comprises the following steps: mixing Co3O4 with a first lithium source, and sintering to obtain large single crystal LiCoO2; uniformly mixing the powder of the large single crystal LiCoO2, at least one of a nickel source, a manganese source and an aluminum source, a second lithium source and a cosolvent, and sintering; the cosolvent is selected from at least one of metal oxides or hydroxides of Zr, Ce and Y; the matching relation of the large single crystal LiCoO2 powder, the first metal source, the second metal source and the second lithium source meets the molar ratio of Ni: CO: (Mn + Al) = x: y: (1-x-y), x is greater than 100% and greater than or equal to 90%, y is greater than or equal to 10% and greater than 0, x + y is less than or equal to 1, Li: (Ni + CO + Mn + Al) = z, and z is greater than or equal to 1.0 and greater than or equal to 1.1. The preparation method can be used for preparing the large single crystal ternary positive electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a ternary positive electrode material and a preparation method thereof, a positive electrode and a battery. Background Art

[0002] With the rapid development of electric vehicles and large-scale energy storage markets, higher requirements are placed on the energy density, cycle life and safety of lithium-ion batteries. Ternary layered cathode materials (such as nickel cobalt manganese / lithium aluminate, referred to as NCM / NCA) have attracted much attention in the field of power batteries due to their high specific capacity and good low-temperature performance. At present, high nickel and high voltage are effective means to improve the energy density of ternary materials, but these strategies may reduce the cycle stability and thermal safety of the materials. Therefore, the development of single-crystal ternary cathode materials is considered to be an effective way to solve the stability problem of high-voltage polycrystalline ternary cathodes.

[0003] Although single crystals have excellent cycle stability and thermal stability, as the molar percentage of Ni is further increased to more than 90% (hereinafter referred to as "ultra-high nickel"), the cycle and thermal stability will deteriorate, which will become an important reason for limiting the large-scale application of ultra-high nickel ternary positive electrode materials. To solve the above problems, common modification methods are doping, coating and large single crystal sintering. Among them, doping and coating modifications are more common, but the effect is limited.

[0004] The sintering of large single crystals usually adopts a simple method of increasing the sintering temperature. The disadvantage is that high temperature will aggravate the mixing of lithium and nickel in ultra-high nickel materials. At the same time, due to the inherent characteristics of NCM (or NCA), when the crystal grows to a certain extent, the temperature sensitivity decreases, which will significantly slow down the growth and has limited effect on the increase of crystal size. It is difficult to achieve an average single crystal particle size of more than 4.0μm.

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

[0006] The object of the present invention is to provide a ternary positive electrode material and a preparation method thereof, a positive electrode and a battery, aiming to improve at least one of the problems mentioned in the background technology.

[0007] The present invention is achieved in that: In a first aspect, the present invention provides a method for preparing a ternary positive electrode material, comprising: Co3O4 is mixed with the first lithium source and sintered at 700-1000°C to obtain large single crystal LiCoO2; The powder of large single crystal LiCoO2, the first metal source, the second metal source, the second lithium source and the solvent are uniformly mixed and sintered at 600-900°C; The first metal source is a nickel source, and the second metal source is at least one of a manganese source and an aluminum source; The co-solvent is selected from at least one of metal oxides or hydroxides of Zr, Ce and Y; The ratio of the large single crystal LiCoO2 powder, the first metal source, the second metal source and the second lithium source satisfies the molar ratio Ni:CO:(Mn+Al)=x:y:(1-xy), 100%>x≥90%, 10%≥y>0, x+y≤1, Li:(Ni+CO+Mn+Al)=z, 1.0≥z≥1.1; The content of the metal elements introduced by the co-solvent in the final ternary positive electrode material is 1000~8000ppm.

[0008] In an optional embodiment, at least one of the following features (1) to (6) is included: (1) the first lithium source is selected from at least one of lithium hydroxide and lithium carbonate; (2) the second lithium source is selected from at least one of lithium hydroxide and lithium carbonate; (3) the nickel source is selected from at least one of nickel oxide and nickel hydroxide; (4) the manganese source is selected from at least one of manganese oxides and hydroxides; (5) The aluminum source is selected from at least one of aluminum oxides and hydroxides; (6) The large single crystal LiCoO2 powder, the first metal source, the second metal source, the second lithium source and the solvent are mixed and sintered for 10 to 15 hours.

[0009] In an optional embodiment, a large single crystal LiCoO2 powder, a first metal source, a second metal source, a second lithium source and a solvent are mixed and sintered to obtain a primary ternary positive electrode material, and after obtaining the primary ternary positive electrode material, the method further comprises: The primary ternary cathode material and the coating agent are mixed and sintered at 300-700° C. in an oxygen atmosphere to obtain a ternary cathode material with a coating layer; The coating agent is at least one of a metal oxide or a fast ion conductor. The effective element introduced by the coating agent has a content of 1000-80000 ppm in the final ternary positive electrode material, and the effective element is selected from at least one of Al, Zr, Ti, Mg, Co, P and B.

[0010] In an optional embodiment, the coating agent is selected from at least one of oxides or hydroxides of Al, Zr, Ti, Mg and Co; Alternatively, at least one salt selected from P and B.

[0011] In an optional embodiment, the time for mixing and sintering the primary ternary positive electrode material and the coating agent is 5 to 7 hours.

[0012] In an optional embodiment, after obtaining the primary ternary positive electrode material, before mixing with the coating agent and sintering, the primary ternary positive electrode material is further broken up to disperse the agglomerated particles.

[0013] In an optional embodiment, before mixing and sintering the large single crystal LiCoO2 powder, the first metal source, the second metal source, the second lithium source and the co-solvent, the method of obtaining the large single crystal LiCoO2 powder includes: The product obtained by sintering Co3O4 and the first lithium source is crushed to disperse the agglomerated particles.

[0014] In a second aspect, the present invention provides a ternary positive electrode material, which is prepared by the preparation method of any one of the aforementioned embodiments.

[0015] In a third aspect, the present invention provides a positive electrode, the active component of which includes the ternary positive electrode material as described in the aforementioned embodiment.

[0016] In a fourth aspect, the present invention provides a battery, comprising the positive electrode according to the aforementioned embodiment.

[0017] The present invention has the following beneficial effects: The preparation method provided by the present invention first prepares a large LiCoO2 single crystal, which has the same layered structure as the ternary positive electrode material, and then uses the large LiCoO2 single crystal as a raw material, and dopes Ni and Mn (or Al) elements on the basis of the large LiCoO2 single crystal, and then adds a solvent that supplements lithium elements and can promote the diffusion of Ni and Mn in the LiCoO2 layered structure for sintering to form a large single crystal ternary positive electrode material. The large single crystal has a lower specific surface area, which can significantly reduce the side reaction between the surface of the positive electrode material and the electrolyte, thereby improving the cycle stability and thermal stability. Compared with the traditional process, the process does not require the preparation of the corresponding precursor, greatly simplifies the production process, reduces the production cost, and is easy to mass produce. At the same time, the process can adjust the molar percentage of the main elements of Ni, Co, and Mn (or Al) by adjusting the Ni and Mn doping amounts, and prepare ternary positive electrode materials of various required proportions, which has great flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figures 1 to 4 The SEM images of the ternary positive electrode materials prepared in Examples 1 to 4 are respectively; Figures 5 to 7 The SEM images of the ternary positive electrode materials prepared in Comparative Examples 1 to 3 are respectively. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0021] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0022] An embodiment of the present invention provides a method for preparing a ternary positive electrode material, comprising: Co3O4 is mixed with the first lithium source and sintered at 700-1000°C to obtain large single crystal LiCoO2; The powder of large single crystal LiCoO2, the first metal source, the second metal source, the second lithium source and the solvent are uniformly mixed and sintered at 600-900°C; The first metal source is a nickel source, and the second metal source is at least one of a manganese source and an aluminum source; The co-solvent is selected from at least one of metal oxides or hydroxides of Zr, Ce and Y; The ratio of the large single crystal LiCoO2 powder, the first metal source, the second metal source and the second lithium source satisfies the molar ratio Ni:CO:(Mn+Al)=x:y:(1-xy), 100%>x≥90%, 10%≥y>0, x+y≤1, Li:(Ni+CO+Mn+Al)=z, 1.0≥z≥1.1; The content of the metal elements introduced by the co-solvent in the final ternary positive electrode material is 1000~8000ppm.

[0023] The preparation method provided by the present invention first prepares a large single crystal of LiCoO2, which has the same layered structure as the ternary positive electrode material, and then uses the large single crystal of LiCoO2 as a raw material, and dopes Ni and Mn (or Al) elements on the basis of the large single crystal of LiCoO2, and then adds a supplementary lithium element and a solvent that can promote the diffusion of Ni and Mn (or Al) in the layered structure of LiCoO2 for sintering to form a large single crystal ternary positive electrode material. The large single crystal has a lower specific surface area, which can significantly reduce the side reaction between the surface of the positive electrode material and the electrolyte, thereby improving the cycle stability and thermal stability. Compared with the traditional process, the process does not require the preparation of the corresponding precursor, greatly simplifies the production process, reduces the production cost, and is easy to mass produce. At the same time, the process can adjust the molar percentage of the main elements of Ni, Co, and Mn (or Al) by adjusting the amount of Ni and Mn (or Al) added, and prepare ternary positive electrode materials of various required proportions, which has great flexibility.

[0024] The preparation method is specifically as follows: S1. Preparation of large single crystal LiCoO2 powder After uniformly mixing Co3O4 and the first lithium source, sintering for 10-15h at 700-1000°C (e.g., 700°C, 800°C, 900°C or 1000°C), preferably 850-950°C, and then crushing the sintered product to disperse the agglomerated particles to obtain a large single crystal LiCoO2 powder; The first lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

[0025] Co3O4 and the first lithium source are mixed in a stoichiometric ratio to generate LiCoO2.

[0026] Since LiCoO2 has a lower surface formation energy, the crystals are easy to grow during the sintering synthesis process, making it easy to prepare larger single crystal particles.

[0027] S2. Evenly mix the powder of large single crystal LiCoO2, the first metal source, the second metal source, the second lithium source and the solvent, and sinter them in an atmosphere containing oxygen at 600-900°C (e.g., 600°C, 700°C, 800°C or 900°C) for 10-15h to obtain a primary ternary positive electrode material.

[0028] The first metal source is a nickel source, and the second metal source is at least one of a manganese source and an aluminum source.

[0029] The auxiliary solvent is selected from at least one of metal oxides or hydroxides of Zr, Ce and Y.

[0030] The ratio of LiCoO2 powder, the first metal source, the second metal source and the second lithium source satisfies the molar ratio Ni:CO:(Mn+Al)=x:y:(1-xy), 100%>x≥90%, 10%≥y>0, Li:(Ni+CO+Mn+Al)=z, 1.0≥z≥1.1.

[0031] The solvent is added in an amount such that the content of the introduced metal element in the finally prepared ternary positive electrode material is 1000-8000 ppm.

[0032] The obtained primary positive electrode material is crushed to disperse the agglomerated particles.

[0033] Optionally, the second lithium source is selected from at least one of lithium hydroxide and lithium carbonate; Optionally, the nickel source is selected from at least one of nickel oxides and hydroxides; Optionally, the manganese source is selected from at least one of manganese oxides and hydroxides; Optionally, the aluminum source is selected from at least one of aluminum oxides and hydroxides. S3. Mix the crushed primary ternary positive electrode material and the coating agent at 300-700°C (e.g., 300°C, 400°C, 500°C, 600°C or 700°C) in an oxygen atmosphere and sinter for 5-7h to obtain a ternary positive electrode material with a coating layer.

[0034] The coating agent is at least one of a metal oxide or a fast ion conductor, the effective element introduced by the coating agent has a content of 1000-80000 ppm in the final ternary positive electrode material, and the effective element is selected from at least one of Al, Zr, Ti, Mg, Co, P and B. The use of metal oxide or fast ion conductor coating and sintering can improve the conductivity of the ternary positive electrode material.

[0035] Optionally, the coating agent is selected from at least one of oxides or hydroxides of Al, Zr, Ti, Mg and Co; or, is selected from at least one of salts of P and B.

[0036] An embodiment of the present invention provides a ternary positive electrode material, which is prepared by using the preparation method provided by the embodiment of the present invention.

[0037] An embodiment of the present invention provides a positive electrode, wherein the active component thereof includes the ternary positive electrode material provided by the embodiment of the present invention.

[0038] A battery provided by an embodiment of the present invention includes the positive electrode provided by an embodiment of the present invention.

[0039] Example 1 10.00kg Co3O4 and 4.60kg Li2CO3 were mixed in a high-speed mixer at 300rpm / min for 5min and then at 900rpm / min for 25min. The uniform mixture was sintered for the first time at 850℃ for 11h, and then crushed to disperse the agglomerated particles to obtain LiCoO2 powder.

[0040] Take 1.00 kg of the above-mentioned LiCoO2 powder and mix it with 0.25 kg MnO2, 9.92 kg NiO, 3.50 kg LiOH and 26.24 g CeO2 in a high-speed mixer, first mix at 300 rpm / min for 5 minutes, and then mix at 900 rpm / min for 30 minutes to obtain a uniform mixture.

[0041] The above uniformly mixed materials were placed in a box furnace for sintering, and the oxygen concentration was maintained above 98% for the second sintering. The sintering temperature was 850°C and the sintering time was 12h to obtain LiNi 0.91 Co 0.07 Mn 0.02 The O2 primary ternary positive electrode material is then crushed to disperse the agglomerated particles.

[0042] 5.00 kg of crushed primary ternary positive electrode material was mixed with 25.17 kg of LiH2PO4 at a stirring speed of 800 rpm / min for 30 minutes, and then sintered for a third time in an oxygen concentration of more than 98% at a sintering temperature of 600°C and a sintering time of 6 hours. The material was sieved to obtain the final ternary positive electrode material with a coating layer; the Ce content was 1500 ppm, and the P content introduced by LiH2PO4 was 1500 ppm.

[0043] Example 2 10.00kg Co3O4 and 4.60kg Li2CO3 were mixed in a high-speed mixer at 300rpm / min for 5min and then at 900rpm / min for 25min. The uniform mixture was sintered for the first time at 900℃ for 11h, and then crushed to disperse the agglomerated particles to obtain LiCoO2 powder.

[0044] Take 1.00 kg of the above-mentioned LiCoO2 powder and mix it with 0.25 kg MnO2, 9.92 kg NiO, 3.50 kg LiOH and 26.24 g CeO2 in a high-speed mixer, first mix at 300 rpm / min for 5 minutes, and then mix at 900 rpm / min for 30 minutes to obtain a uniform mixture.

[0045] The above uniformly mixed materials were placed in a box furnace for sintering, and the oxygen concentration was maintained above 98% for the second sintering. The sintering temperature was 850°C and the sintering time was 12h to obtain LiNi 0.91 Co 0.07 Mn 0.02 The O2 primary ternary positive electrode material is then crushed to disperse the agglomerated particles.

[0046] 5.00 kg of crushed primary ternary positive electrode material was mixed with 25.17 kg of LiH2PO4 at a stirring speed of 800 rpm / min for 30 minutes, and then sintered for a third time in an oxygen concentration of more than 98% at a sintering temperature of 600°C and a sintering time of 6 hours. The material was sieved to obtain the final ternary positive electrode material with a coating layer; the Ce content was 1500 ppm, and the P content introduced by LiH2PO4 was 1500 ppm.

[0047] Example 3 10.00kg Co3O4 and 4.60kg Li2CO3 were mixed in a high-speed mixer at 300rpm / min for 5min and then at 900rpm / min for 25min. The uniform mixture was sintered for the first time at 950℃ for 11h, and then crushed to disperse the agglomerated particles to obtain LiCoO2 powder.

[0048] Take 1.00 kg of the above-mentioned LiCoO2 powder and mix it with 0.25 kg MnO2, 9.92 kg NiO, 3.50 kg LiOH and 26.24 g CeO2 in a high-speed mixer, first mix at 300 rpm / min for 5 minutes, and then mix at 900 rpm / min for 30 minutes to obtain a uniform mixture.

[0049] The above uniformly mixed materials were placed in a box furnace for sintering, and the oxygen concentration was maintained above 98% for the second sintering. The sintering temperature was 850°C and the sintering time was 12h to obtain LiNi 0.91 Co 0.07 Mn 0.02 The O2 primary ternary positive electrode material is then crushed to disperse the agglomerated particles.

[0050] 5.00 kg of crushed primary ternary positive electrode material was mixed with 25.17 kg of LiH2PO4 at a stirring speed of 800 rpm / min for 30 minutes, and then sintered for a third time in an oxygen concentration of more than 98% at a sintering temperature of 600°C and a sintering time of 6 hours. The material was sieved to obtain the final ternary positive electrode material with a coating layer, wherein the Ce content was 1500 ppm and the lithium content introduced by the coating agent was 1500 ppm.

[0051] Example 4 10.00kg Co3O4 and 4.60kg Li2CO3 were mixed in a high-speed mixer at 300rpm / min for 5min and then at 900rpm / min for 25min. The uniform mixture was sintered for the first time at 850℃ for 11h, and then crushed to disperse the agglomerated particles to obtain LiCoO2 powder.

[0052] Take 1.00 kg of the above-mentioned LiCoO2 powder and mix it with 0.15 kg Al2O3, 9.92 kg NiO, 3.50 kg LiOH and 26.24 g CeO2 in a high-speed mixer, first mix at 300 rpm / min for 5 minutes, and then mix at 900 rpm / min for 30 minutes to obtain a uniform mixture.

[0053] The above uniformly mixed materials were placed in a box furnace for sintering, and the oxygen concentration was maintained above 98% for the second sintering. The sintering temperature was 850°C and the sintering time was 12h to obtain LiNi 0.91 Co 0.07 Mn 0.02 The O2 primary ternary positive electrode material is then crushed to disperse the agglomerated particles.

[0054] 5.00 kg of crushed primary ternary positive electrode material was mixed with 25.17 kg of LiH2PO4 at a stirring speed of 800 rpm / min for 30 minutes, and then sintered for a third time in an oxygen concentration of more than 98% at a sintering temperature of 600°C and a sintering time of 6 hours. The material was sieved to obtain the final ternary positive electrode material with a coating layer, wherein the Ce content was 1500 ppm and the lithium content introduced by the coating agent was 1500 ppm.

[0055] Example 5 This embodiment is basically the same as the embodiment 1, except that the auxiliary solvent is ZrO2, and the content of the introduced zirconium element in the prepared positive electrode material is 4000 ppm.

[0056] Example 6 This embodiment is basically the same as the embodiment 1, except that the auxiliary solvent is Zr(OH)4, and the content of the introduced zirconium element in the prepared positive electrode material is 4000 ppm.

[0057] Example 7 This embodiment is basically the same as the embodiment 1, except that the temperature during the first sintering is 700°C, the temperature during the second sintering is 600°C, and the temperature during the third sintering is 300°C.

[0058] Comparative Example 1 10.00kg NCM precursor Ni 0.91 Co 0.07 Mn 0.02 (OH)2 and 4.85 kg of powdered lithium hydroxide were added into a high-speed stirring mixer, first mixed at 300 rpm / min for 5 min, and then mixed at 900 rpm / min for 30 min to obtain a uniform mixture.

[0059] The mixed material was placed in a box furnace for sintering, and the oxygen concentration was maintained above 98%. The first sintering was performed at a sintering temperature of 800°C and a sintering time of 12 hours. The mixed material was pulverized under the same pulverizing conditions as in Example 1 to disperse the agglomerated particles and obtain a process material.

[0060] 5.00kg of the process material was mixed with 25.17kg of LiH2PO4 for coating. The coating stirring speed was 800rpm / min and the mixing lasted for 30min. Then, the secondary sintering was carried out at 600℃ for 6h in an oxygen concentration of more than 98%, and the final product Ni was obtained by sieving. 0.91 Co 0.07 Mn 0.02 O2.

[0061] Comparative Example 2 10.00kg NCM precursor Ni 0.91 Co 0.07 Mn 0.02 (OH)2 and 4.85 kg of powdered lithium hydroxide were added into a high-speed stirring mixer, first mixed at 300 rpm / min for 5 min, and then mixed at 900 rpm / min for 30 min to obtain a uniform mixture.

[0062] The mixed material was placed in a box furnace for sintering, and the oxygen concentration was maintained above 98%. The first sintering was performed at a sintering temperature of 850°C and a sintering time of 12 hours. The mixed material was pulverized under the same pulverizing conditions as in Example 1 to disperse the agglomerated particles and obtain a process material.

[0063] 5.00kg of the process material was mixed with 25.17kg of LiH2PO4 for coating. The coating stirring speed was 800rpm / min and the mixing lasted for 30min. Then, the secondary sintering was carried out at 600℃ for 6h in an oxygen concentration of more than 98%, and the final product Ni was obtained by sieving. 0.91 Co 0.07 Mn 0.02 O2.

[0064] Comparative Example 3 10.00kg NCM precursor Ni 0.91Co 0.07 Mn 0.02 (OH)2 and 4.85 kg of powdered lithium hydroxide were added into a high-speed stirring mixer, first mixed at 300 rpm / min for 5 min, and then mixed at 900 rpm / min for 30 min to obtain a uniform mixture.

[0065] The mixed material was placed in a box furnace for sintering, and the oxygen concentration was maintained above 98%. The first sintering was carried out at a sintering temperature of 900°C and a sintering time of 12 hours. The mixed material was pulverized under the same pulverizing conditions as in Example 1 to disperse the agglomerated particles and obtain a process material.

[0066] 5.00kg of the process material was mixed with 25.17kg of LiH2PO4 for coating. The coating stirring speed was 800rpm / min and the mixing lasted for 30min. Then, the secondary sintering was carried out at 600℃ for 6h in an oxygen concentration of more than 98%, and the final product Ni was obtained by sieving. 0.91 Co 0.07 Mn 0.02 O2.

[0067] Comparative Example 4 This comparative example is substantially the same as Example 1, except that no co-solvent is added.

[0068] Experimental example (1) SEM images of the positive electrode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were taken, as shown in FIG. Figures 1 to 7 shown.

[0069] The grain sizes are recorded in Table 1. It can be seen from the figure and Table 1 that the single grain size of the positive electrode material prepared in each embodiment of the present invention is significantly larger than that of the comparative example.

[0070] (2) Testing the residual alkali content of the prepared positive electrode material using the acid-base titration method of GB / T 9724-2007; The cathode material is tested by the nitrogen adsorption method GB / T 19587-2004 to prepare the cathode material into a battery, and the capacity retention rate after 50 cycles at high temperature (45°C) is measured, corresponding to a charge and discharge rate of 1C / 1C.

[0071] Record the test results in Table 1.

[0072] Table 1 Process parameters and performance data of various embodiments and comparative examples

[0073] Comparing the data of Examples 1-3, it can be seen that when the first sintering temperature is increased from 850°C to 900°C, the average grain size increases from 9.0 μm to 10.2 μm, and the specific surface area increases from 0.32 m 2 / g is reduced to 0.23m 2 / g, the 50-week high temperature retention rate increased from 96.3% to 97.2%. When the temperature was further increased to 950℃, there was no significant change in grain size, specific surface and high temperature cycle, indicating that the temperature sensitivity of material growth to temperature was significantly reduced when the temperature was further increased on the basis of 950℃. The three primary sintering temperatures had little effect on the residual alkali of the finished product. Considering the higher energy demand and equipment requirements at higher temperatures, sintering at 900℃ was the best choice.

[0074] Comparing Example 1 with Example 4, it can be seen that after replacing Mn with Al, under the same process synthesis conditions, there is no significant difference in the average grain size, residual alkali and cycle, indicating that the process of preparing NCM with Mn doping and preparing NCA with Al doping can achieve the same material performance. Comparative Examples 1 to 3 are prepared by using conventional process NCM precursors to prepare ternary positive electrode materials. Comparative Examples 1 to 3 are compared. The primary sintering temperature is increased from 800°C to 850°C, the finished product particle size is increased by about 25%, and the specific surface area is reduced by 0.09m 2 / g, and the 50-week high-temperature cycle performance increased by 1.3%. Further increasing the primary sintering temperature to 900°C did not significantly improve the particle size and high-temperature cycle performance. At the same time, it was found that by using a precursor process to increase the primary sintering temperature, the residual alkali LiOH content will gradually increase, which is not conducive to subsequent slurry processing. On the whole, the better process of Comparative Examples 1 to 3 is Comparative Example 2. By comparing Example 2 with Comparative Example 2, it was found that the particle size of the single crystal prepared by the precursor-free process is about 3 times that of the single crystal prepared by the precursor process, the residual alkali LiOH is about 700ppm lower, and the specific surface area is 0.47m lower. 2 / g, and 50-week high-temperature cycle is 3.3% higher. The performance of the finished product prepared by the precursor-free process is significantly better than that of the finished product prepared by the precursor process.

[0075] Comparing Comparative Example 4 with Example 1, the average particle size of the ternary positive electrode material prepared in Comparative Example 4 is significantly smaller than that in Example 1, and the cycle performance is also worse than that in Example 1. It can be seen that if no co-solvent is added during the preparation process, it is difficult to obtain a better effect of the prepared ternary positive electrode material.

[0076] In summary, the preparation method provided by the present invention uses a precursor-free lithium cobalt oxide process to produce larger single crystal particles than a conventional precursor process, thereby showing excellent material stability. At the same time, the precursor-free lithium cobalt oxide process does not require the preparation of precursors again, greatly simplifies the production process of ternary positive electrode materials, reduces production costs, and facilitates large-scale production.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a ternary positive electrode material, characterized in that: include: Co3O4 is mixed with the first lithium source and sintered at 700-1000°C to obtain large single crystal LiCoO2; The large single crystal LiCoO2 powder, the first metal source, the second metal source, the second lithium source and the solvent are uniformly mixed and then sintered at 600-900° C.; The first metal source is a nickel source, and the second metal source is at least one of a manganese source and an aluminum source; The co-solvent is selected from at least one of metal oxides or hydroxides of Zr, Ce and Y; The ratio of the large single crystal LiCoO2 powder, the first metal source, the second metal source and the second lithium source satisfies the molar ratio Ni:CO:(Mn+Al)=x:y:(1-xy), 100%>x≥90%, 10%≥y>0, x+y≤1, Li:(Ni+CO+Mn+Al)=z, 1.0≥z≥1.1; The content of the metal element introduced by the co-solvent in the finally prepared ternary positive electrode material is 1000-8000 ppm.

2. The preparation method according to claim 1, characterized in that: Includes at least one of the following features (1) to (6): (1) The first lithium source is selected from at least one of lithium hydroxide and lithium carbonate; (2) The second lithium source is selected from at least one of lithium hydroxide and lithium carbonate; (3) The nickel source is selected from at least one of nickel oxide and nickel hydroxide; (4) The manganese source is selected from at least one of manganese oxides and hydroxides; (5) The aluminum source is selected from at least one of aluminum oxides and hydroxides; (6) The large single crystal LiCoO2 powder, the first metal source, the second metal source, the second lithium source and the solvent are mixed and sintered for 10 to 15 hours.

3. The preparation method according to claim 1, characterized in that: The powder of large single crystal LiCoO2, the first metal source, the second metal source, the second lithium source and the co-solvent are mixed and sintered to obtain a primary ternary positive electrode material, and after obtaining the primary ternary positive electrode material, the further step includes: The primary ternary positive electrode material and the coating agent are mixed and sintered at 300-700° C. in an oxygen atmosphere to obtain a ternary positive electrode material with a coating layer; The coating agent is at least one of a metal oxide or a fast ion conductor, and the effective element introduced by the coating agent has a content of 1000-80000 ppm in the final ternary positive electrode material, and the effective element is selected from at least one of Al, Zr, Ti, Mg, Co, P and B.

4. The preparation method according to claim 3, characterized in that: The coating agent is selected from at least one of the oxides or hydroxides of Al, Zr, Ti, Mg and Co; Alternatively, at least one salt selected from P and B.

5. The preparation method according to claim 3, characterized in that: The time for mixing and sintering the primary ternary positive electrode material and the coating agent is 5 to 7 hours.

6. The preparation method according to claim 3, characterized in that: After obtaining the primary ternary positive electrode material, before mixing with the coating agent and sintering, the primary ternary positive electrode material is further broken to disperse the agglomerated particles.

7. The preparation method according to claim 1, characterized in that: Before mixing and sintering the large single crystal LiCoO2 powder, the first metal source, the second metal source, the second lithium source and the co-solvent, the method of obtaining the large single crystal LiCoO2 powder includes: The product obtained by sintering Co3O4 and the first lithium source is crushed to disperse the agglomerated particles.

8. A ternary positive electrode material, characterized in that: The method is prepared according to any one of claims 1 to 7.

9. A positive electrode, characterized in that: Its active ingredients include the ternary positive electrode material as claimed in claim 8.

10. A battery, characterized in that: Comprising the positive electrode as claimed in claim 9.

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