Lithium zirconium phosphate fast ion conductor coated nickel cobalt lithium aluminate positive electrode material and preparation method

Abstract

Lithium zirconium phosphate fast ion conductor coated nickel cobalt lithium aluminate positive electrode material and preparation method thereof, the mass of the lithium zirconium phosphate fast ion conductor is 0.1-10wt%, and the lithium zirconium phosphate fast ion conductor is formed into a layer with a thickness of 5-30nm The coating layer is coated on lithium nickel cobalt aluminate; the positive electrode material is a spherical particle with a particle diameter of 5-15 μm. The preparation method includes the following steps: (1) Prepare a solution containing phosphorus source and zirconium source, add zirconium source solution in organic solvent or water, then add phosphorus source solution, stir, then add nickel-cobalt lithium aluminate, heat and stir to react , slowly evaporated to dryness, and put the obtained powder into an oven for drying; (2) Put the powder obtained in step (1) in a tube furnace for low-temperature rapid sintering. The positive electrode material of the present invention has good cycle stability and rate discharge performance; the method of the present invention can effectively reduce the problems of surface residual lithium and low cycle stability of ternary materials during conventional coating, the process cost is low, the process is simple, and it is suitable for large industrial production.

Description

technical field [0001] The invention relates to a positive electrode material and a preparation method thereof, in particular to a lithium zirconium phosphate fast ion conductor coated nickel-cobalt lithium aluminate positive electrode material and a preparation method thereof. Background technique [0002] Lithium-ion batteries are considered to be one of the most promising energy storage cycle systems that can realize power batteries. They have the advantages of high energy density, high working voltage, good safety performance, stable cost, and low toxicity. The development of lithium-ion batteries is of great significance for solving energy shortages and reducing environmental pollution. Among them, the cathode material is the key factor that determines the electrochemical performance, safety performance and price cost of lithium-ion batteries. However, the ternary cathode materials that currently dominate the market still cannot meet the needs of the development of elec...

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Problems solved by technology

[0003] Patent CN105406069 A discloses a method for coating ternary materials with lithium manganese iron phosphate. In this method, ascorbic acid is mixed with lithium manganese phosphate, mixed with ternary materials, and then vacuum-dried. The method involves the participation of acidic substances in the coating process. The ternary material is an oxide and is easily corroded by acidic substances. Therefore, the method has shortcomings and the improvement of the ternary material is limited.

[0004] CN107230771 A discloses a kind of method of vanadium phosphate coating ternary material, this method mixes vanadium salt and phosphate reducing agent in deionized water, after stirring, filter, wash, dry and ternary material according to 1~10: The ingredient ratio is 100, mixed in a high-speed mixer, and then heat-preserved and sintered at 200-400 degrees under a non-oxygen atmosphere to obtain a coated ternary coated modified material. Mixing, uneven coating, weak interaction between solid particles, it is difficult to achieve film formation or uniform mixing, and the residual lithium on the solid-phase mixed ternary surface still exists in the solid phase on the ternary surface, which still affects the cycle performance of the ternary. This coating method has limited improvement in the cycle performance of the ternary, and there is a problem of uneven coating

[0005] Patent CN105047864 A discloses a method of using lithium zirconate to coat ternary materials. This method utilizes the nickel-cobalt-manganese precursor prepared by oxalate and tetrabutyl zirconate to react hydrothermally at 180 degrees to form a zirconia coating layer. Then sinter at high temperature to obtain the coating material of lithium zirconate. This method uses a liquid phase zirconium source, and tetrabutyl zirconate is used as the coating material, because the liquid phase should have better dispersion relative to the solid phase. solution, so better coating can be achieved, but the electrochemical performance after coating still needs to be further improved

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