High-Nickel Single-Crystal Cathode Material of Lithium Nickel Cobalt Manganese Oxide and Method for Producing the Same

Abstract

The present invention discloses a lithium nickel cobalt manganese oxide high nickel single crystal positive electrode material and its manufacturing method. The manufacturing method includes the steps of mixing nickel cobalt manganese hydroxide with a lithium source, zirconia, tungsten oxide, and sodium carbonate, ball milling the mixture, and then performing primary sintering at a temperature 50-150°C higher than the normal sintering temperature, followed by pulverization to obtain a lithium nickel cobalt manganese oxide high nickel single crystal positive electrode material intermediate, and uniformly mixing the lithium nickel cobalt manganese oxide high nickel single crystal positive electrode material intermediate with a coating agent, and performing secondary sintering to obtain a lithium nickel cobalt manganese oxide high nickel single crystal positive electrode material. In the present invention, by introducing tungsten oxide and sodium carbonate in the primary sintering process, not only can the conductivity of the material be improved, but also the particle morphology can be changed to make the primary particles finer. By utilizing the characteristics of combining tungsten oxide and sodium carbonate, and further combining it with the doping of zirconia, a high nickel single crystal positive electrode material with high capacity, high dispersibility, and excellent cycle characteristics can be obtained at a high primary sintering temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide and a method for manufacturing the same.

Background Art

[0002] LiNi x Co y Mn 1-x-y The LiNi x Co y Mn 1-x-y O2 ternary cathode material has the characteristics of high specific capacity, high energy density, low cost, and environmental friendliness, so it is widely used in lithium-ion secondary batteries. Especially in the current background, it has the potential for development in the market of automotive power batteries. With the improvement of the cruising range, the current cathode materials are gradually evolving towards higher nickel content and higher voltage. Single-crystal cathode materials have attracted much attention because of their advantages of relatively high compression rate of the electrode plate and low gas generation amount. However, there are the following two problems in the sintering process of high-nickel single-crystal materials. First, when the sintering temperature is slightly low, although the discharge specific capacity is high, the single crystals aggregate and the dispersibility is poor. As a result, the cycle characteristics deteriorate and the gas generation amount increases. Second, when the sintering temperature is too high, the single-crystal size is large and the dispersibility is good, but the discharge specific capacity decreases significantly.

[0003] Therefore, how to manufacture a high-nickel single-crystal cathode material with high capacity, large size and high dispersibility is still a major problem.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of the present invention is to eliminate the above-mentioned technical defects, propose a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide and a method for manufacturing the same, and solve the technical problem of the prior art that the high-nickel single-crystal cathode material cannot have high capacity, large size and high dispersibility at the same time.

Means for Solving the Problems

[0005] The first aspect of the present invention is After mixing nickel-cobalt-manganese hydroxide with a lithium source, zirconia, tungsten oxide, and sodium carbonate and performing ball milling, primary sintering is carried out at a temperature 50 to 150 °C higher than the normal sintering temperature, followed by pulverization to obtain an intermediate of a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide, and after uniformly mixing the intermediate of the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide with a coating agent, secondary sintering is carried out to obtain a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide. A method for manufacturing a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide is provided, including the steps of

[0006] The second aspect of the present invention provides a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide obtained by the method for manufacturing a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide according to the first aspect of the present invention.

Advantages of the Invention

[0007] Compared with the prior art, the beneficial effects of the present invention include the following.

[0008] In the present invention, tungsten oxide and sodium carbonate are introduced in the primary sintering process. Since there are oxygen vacancies inside the high-nickel material and some sodium ions occupy lithium sites, the W-O octahedron is distorted in various ways such as tilting and rotation, and the unit cell and electronic structure of the material are affected to various degrees. Thereby, not only can the conductivity of the material be improved, but also the particle morphology can be changed to refine the primary particles. By utilizing the characteristic of combining tungsten oxide and sodium carbonate and further combining with zirconia doping, a high-nickel single-crystal cathode material with high capacity, high dispersibility, and excellent cycle characteristics is obtained at a high primary sintering temperature.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0010] In order to more clearly understand the object, technical solution and advantages of the present invention, the present invention will be described in more detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0011] The first aspect of the present invention is Step S1 of obtaining an intermediate of a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide by mixing nickel-cobalt-manganese hydroxide with a lithium source, zirconia, tungsten oxide, and sodium carbonate, performing ball milling, and then performing primary sintering at a temperature 50 to 150 °C higher than the normal sintering temperature, and pulverizing; A method for manufacturing a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide is provided, including step S2 of uniformly mixing a high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganese oxide with a coating agent and then performing secondary sintering to obtain the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide.

[0012] In the present invention, tungsten oxide and sodium carbonate are introduced as dopants in the primary sintering process. Since there are oxygen vacancies inside the high-nickel material and some sodium ions occupy lithium sites, the W-O octahedron is distorted in various ways such as tilting and rotation, which affects the unit cell and electronic structure of the material to varying degrees. Thereby, not only can the conductivity of the material be improved, but also the particle morphology can be changed to refine the primary particles. By utilizing the property of combining tungsten oxide and sodium carbonate and further combining with zirconia doping, a high-nickel single-crystal cathode material with high capacity, high dispersibility, and excellent cycle characteristics is obtained at a high primary sintering temperature. However, the sintering temperature should not be too high. If the sintering temperature is too high, it will lead to excessive growth of single crystals, extension of lithium ion transport paths, and reduction of ionic conductivity. As a result, the capacity and rate characteristics will decrease.

[0013] In the present invention, the chemical composition of nickel-cobalt-manganese hydroxide is Ni x Co y Mn 1-x-y (OH)2 (0.7 ≤ x ≤ 0.95, 0.02 ≤ y ≤ 0.25). In some specific embodiments of the present invention, the chemical composition of the high-nickel single-crystal cathode material precursor of lithium nickel cobalt manganese oxide is Ni 0.80 Co 0.10 Mn 0.10 (OH)2.

[0014] In the present invention, the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride, and the molar ratio of lithium in the nickel-cobalt-manganese hydroxide to the lithium in the lithium source is 1:(1.01 - 1.1).

[0015] In the present invention, the molar ratio of nickel-cobalt-manganese hydroxide, zirconia, tungsten oxide, and sodium carbonate is 1:(0.001 to 0.005):(0.001 to 0.005):(0.001 to 0.005), and further 1:0.002:0.0016:0.002. By introducing tungsten oxide, sodium carbonate, and zirconia into the system by doping, a single crystal material with good dispersibility and excellent discharge specific capacity and cycle characteristics can be obtained. However, the content of the introduced sodium carbonate should not be too high. If this addition amount is too large, the residual alkali amount in the system will increase, which is disadvantageous for improving the performance of the battery.

[0016] In the present invention, the primary sintering temperature is T1, the normal sintering temperature is T2, and ΔT = T1 - T2 = 50 to 150°C, further 60 to 100°C, and even further 70 to 80°C. The normal sintering temperature T2 is the sintering temperature (i.e., the optimum sintering temperature) at which the discharge specific capacity is the largest and the single crystal dispersibility is the best as a result of performing an electrochemical test on the primary sintered body of the nickel-cobalt-manganese single crystal cathode material obtained by a primary sintering DOE test using nickel-cobalt-manganese hydroxide and a lithium source. The optimum sintering temperature is related to the molar ratio of the transition metal elements of nickel-cobalt-manganese hydroxide and the mixing ratio of lithium. Different nickel-cobalt-manganese hydroxides and different mixing ratios of lithium all correspond to different optimum sintering temperatures. For example, when the mixing ratio of lithium in Ni 0.8 Co 0.1 Mn 0.1 (OH)2 and lithium hydroxide is 1.05, the optimum sintering temperature is 870°C.

[0017] In the present invention, the time for primary sintering is 10 to 20 h.

[0018] In the present invention, the type of the coating agent is not limited and can be selected by those skilled in the art according to actual needs. For example, the coating agent may be an oxide or hydroxide of B, Al, Mg, V, Ti, P, Si, and Y. The addition amount of the coating agent is 0.05 wt% to 5 wt% of the total amount of the high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganate. In this process, the temperature of the secondary sintering is 200 to 600 °C, and the time of the secondary sintering is 6 to 24 h. In the present invention, by forming a coating layer on the surface of the high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganate, the side reaction between the single crystal and the electrolyte can be reduced, and the service life of the battery can be further extended.

[0019] In the present invention, both the primary sintering process and the secondary sintering process are carried out under oxygen gas conditions.

[0020] The second aspect of the present invention provides a high-nickel single-crystal cathode material of lithium nickel cobalt manganate obtained by the manufacturing method of the high-nickel single-crystal cathode material of lithium nickel cobalt manganate according to the first aspect of the present invention.

Example

[0021] Example 1 (1) 2.0 kg of Ni 0.80 Co 0.10 Mn 0.10 (OH)2 powder, 0.93 kg of LiOH·H2O, 5.78 g of nano ZrO2, 8.10 g of WO3, and 4.95 g of sodium carbonate were weighed, uniformly mixed by a ball mill, and then the mixed material was put into an oxygen atmosphere furnace and calcined at a calcination temperature of 950 °C and a sintering time of 15 h. After the reaction was completed, cooling, pulverization, and sieving were performed to obtain a high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganate. (2) 4.65 g of Y2O3 was uniformly mixed with the high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganate, and then heat-treated at 500 °C for 10 h in a high-oxygen atmosphere to obtain a high-nickel single-crystal cathode material of lithium nickel cobalt manganate coated with yttrium.

[0022] Example 2 (1) Ni 0.80 Co 0.10 Mn 0.10 (1) Weighed 2.0 kg of Ni(OH)2 powder, 0.93 kg of LiOH·H2O, 5.78 g of nano ZrO2, 8.10 g of WO3, and 4.95 g of sodium carbonate, uniformly mixed them with a ball mill, then put the mixed material into an oxygen atmosphere furnace, calcined at a calcination temperature of 930 °C and a sintering time of 20 h. After the reaction was completed, it was cooled, pulverized, and sieved to obtain a high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganese oxide. (2) After uniformly mixing 4.65 g of Y2O3 with the high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganese oxide, heat-treated it at 500 °C for 10 h in a high-oxygen atmosphere to obtain a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide coated with yttrium.

[0023] Example 3 (1) Ni 0.80 Co 0.10 Mn 0.10 (1) Weighed 2.0 kg of Ni(OH)2 powder, 0.93 kg of LiOH·H2O, 5.78 g of nano ZrO2, 8.10 g of WO3, and 4.95 g of sodium carbonate, uniformly mixed them with a ball mill, then put the mixed material into an oxygen atmosphere furnace, calcined at a calcination temperature of 970 °C and a sintering time of 10 h. After the reaction was completed, it was cooled, pulverized, and sieved to obtain a high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganese oxide. (2) After uniformly mixing 4.65 g of Y2O3 with the high-nickel single-crystal cathode material intermediate of lithium nickel cobalt manganese oxide, heat-treated it at 500 °C for 10 h in a high-oxygen atmosphere to obtain a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide coated with yttrium.

[0024] Comparative Example 1 Compared with Example 1, the only difference is that the dopant is only zirconia.

[0025] Comparative Example 2 As compared with Example 1, the only difference is that WO3 is not added as a dopant.

[0026] Comparative Example 3 As compared with Example 1, the only difference is that sodium carbonate is not added as a dopant.

[0027] Comparative Example 4 As compared with Example 1, the only difference is that zirconia is not added as a dopant.

[0028] Comparative Example 5 As compared with Example 1, the only difference is that the temperature of the first sintering is 870 °C.

[0029] Comparative Example 6 As compared with Example 1, the only difference is that the temperature of the first sintering is 1050 °C.

[0030] Test group The results of SEM tests on the positive electrode materials manufactured in Example 1 and Comparative Examples 1 to 6 of the present invention are shown in FIGS. 1 to 7 and Table 1.

[0031] The positive electrode materials manufactured in Example 1 and Comparative Examples 1 to 6 of the present invention were uniformly mixed with acetylene carbon black as a conductive agent and PVDF as a binder at a mass ratio of 92:4:4, an appropriate amount of 1-methyl-2-pyrrolidone was added, and ball milling was performed for 1 hour to form a slurry, which was uniformly coated on an aluminum sheet, dried, and pressed to manufacture a positive electrode plate. A 2032 button battery was assembled with a metallic lithium sheet as the negative electrode, and an electrical property test was performed using a LAND test system. The charge and discharge voltage was set to 3.0 to 4.3 V. In the first cycle, charge and discharge were performed at 0.2C / 0.2C, and then 200 cycles were performed at 1C / 1C. The results are shown in Table 1.

[0032] [Table 1]

[0033] As can be seen from Table 1, compared with Comparative Examples 1 to 6, the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide manufactured in Example 1 of the present invention has a large single-crystal size, good dispersibility, a high discharge specific capacity, and was also found to have good cycling stability.

[0034] Compared with Example 1, although the average particle size of the high-nickel single-crystal cathode material obtained in Comparative Example 1 was large, its discharge specific capacity and cycle characteristics were still inferior. The reason is that in Comparative Example 1, only zirconia was added, and there was no effect of tungsten oxide and sodium carbonate, so its sintering temperature was too high and its electrochemical properties were still inferior.

[0035] Compared with Example 1, although the average particle size of the high-nickel single-crystal cathode material obtained in Comparative Example 2 was large, its discharge specific capacity and cycle characteristics were still inferior. The reason is that in Comparative Example 2, tungsten oxide was not added, and the effect of tungsten oxide, which improves conductivity in the system and refines primary particles, could not be exerted. As a result, the electrochemical properties of the high-nickel single-crystal cathode material obtained in Comparative Example 2 were inferior.

[0036] Compared with Example 1, the average particle size of the high-nickel single-crystal cathode material obtained in Comparative Example 3 decreased significantly, and its discharge specific capacity and cycle characteristics were inferior. The reason is that in Comparative Example 3, sodium carbonate was not added, and it could not function in combination with tungsten oxide to increase the single-crystal size and improve the dispersibility. As a result, the electrochemical properties of the high-nickel single-crystal cathode material obtained in Comparative Example 3 were inferior.

[0037] Compared with Example 1, the high-nickel single-crystal cathode material obtained in Comparative Example 4 had a large single-crystal size, good dispersibility, and a high discharge specific capacity, but its cycle characteristics were inferior. The reason is that in Comparative Example 4, zirconia was not doped, so the crystal structure stability was lower than that of Example 1.

[0038] Compared with Example 1, the high-nickel single-crystal cathode material obtained in Comparative Example 5 showed a significant decrease in both the average particle size and the cycle performance. The reason is that in Comparative Example 5, since the high sintering temperature was not increased, the obtained cathode material had a small single-crystal size, poor dispersibility, and a significant decrease in cycle performance.

[0039] Compared with Example 1, the high-nickel single-crystal cathode material obtained in Comparative Example 6 showed a significant increase in the average particle size, but a significant decrease in both the discharge specific capacity and the cycle performance. The reason is that in Comparative Example 6, since the sintering temperature was too high, the single crystals grew excessively, the lithium-ion transport path became longer, the ionic conductivity decreased, and as a result, the capacity and rate performance decreased.

[0040] The above specific embodiments of the present invention do not limit the protection scope of the present invention. All other corresponding changes and modifications made based on the technical idea of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide, comprising: Mixing nickel cobalt manganese hydroxide with a lithium source, zirconia, tungsten oxide, and sodium carbonate, followed by ball milling, then performing primary sintering at a temperature 60 to 100 °C higher than the normal sintering temperature, pulverizing to obtain an intermediate of the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide, wherein the molar ratio of the nickel cobalt manganese hydroxide, zirconia, tungsten oxide, and sodium carbonate is 1:(0.001 - 0.005):(0.001 - 0.005):(0.001 - 0.005), the normal sintering temperature is the sintering temperature at which, as a result of performing an electrochemical test on the primary sintered body of the nickel cobalt manganese single-crystal cathode material obtained by a primary sintering DOE test using the nickel cobalt manganese hydroxide and the lithium source, the discharge specific capacity is the largest and the single-crystal dispersibility is the best, and the time of the primary sintering is 10 to 20 h; After uniformly mixing the intermediate of the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide with a coating agent, performing secondary sintering to obtain the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide, wherein the coating agent is at least one of oxides or hydroxides of B, Al, Mg, V, Ti, P, Si, and Y, the addition amount of the coating agent is 0.05 wt% to 5 wt% of the total amount of the intermediate of the high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide, the temperature of the secondary sintering is 200 to 600 °C, and the time of the secondary sintering is 6 to 24 h; The chemical composition of the nickel cobalt manganese hydroxide is Ni x Co y Mn 1-x-y (OH) 2 (0.7 ≤ x ≤ 0.95, 0.02 ≤ y ≤ 0.25).

2. The method for manufacturing a high-nickel single-crystal cathode material of lithium nickel cobalt manganese oxide according to Claim 1, wherein the primary sintering temperature is 70 to 80 °C higher than the normal sintering temperature.

3. The lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride, and the molar ratio of the nickel cobalt manganese hydroxide to lithium in the lithium source is 1:(1.01 to 1.1). A method for producing a high-nickel single-crystal cathode material for lithium nickel cobalt manganese oxide according to claim 1, characterized in that.

4.

5. The method for producing a high-nickel single-crystal cathode material for lithium nickel cobalt manganese oxide according to claim 1, characterized in that the molar ratio of the nickel cobalt manganese hydroxide, zirconia, tungsten oxide, and sodium carbonate is 1:0.002:0.0016:0.

002.

5.

6. The method for producing a high-nickel single-crystal cathode material for lithium nickel cobalt manganese oxide according to claim 1, characterized in that both the primary sintering process and the secondary sintering process are carried out under conditions where oxygen gas is present.

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