Aluminum-phosphate coated lithium-nickel-cobalt-aluminate positive electrode material and preparation method thereof

Abstract

The invention discloses an aluminum-phosphate coated lithium-nickel-cobalt-aluminate positive electrode material. The chemical expression of the material is LiaNixCoyAlzPcO2, wherein a is greater thanor equal to 1 and less than or equal to 1.2, x is greater than or equal to 0.3 and less than or equal to 0.98, y is greater than or equal to 0.01 and less than or equal to 0.6, z is greater than or equal to 0.001 and less than or equal to 0.2, b is greater than or equal to 0.00001 and less than or equal to 0.03, and c is greater than or equal to 0.001 and less than or equal to 0.01. The inventionalso discloses a preparation method of the positive electrode material. Soluble aluminum salt is used as an Al source, soluble phosphate is used as a precipitant, and a layer of AlPO4 coating layer is uniformly plated on the surface of a positive electrode material by controlling a crystallization chemical plating method. The method is simple and easy to operate, the coating amount of AlPO4 can be accurately controlled, and the precipitation problem is solved by a surfactant in the coating process, thereby enabling the coating layer to be thin and uniform, prolonging the cycle life of the positive electrode material, and improving the safety performance of the positive electrode material.

Description

technical field [0001] The invention belongs to the technical field of battery materials, and in particular relates to a nickel-cobalt-lithium-aluminate cathode material coated with aluminum phosphate and a preparation method thereof. Background technique [0002] Nickel-cobalt-aluminum ternary lithium-ion battery cathode materials are widely used in IT products and new energy vehicles due to their high energy density and relatively simple preparation process. However, lithium nickel-cobalt aluminate (LNCA) has poor structural stability Good, high-priced nickel is easy to react with the electrolyte, causing the electrolyte to decompose and release gas, causing great harm to the cycle life and safety of the material; to solve the above problems, surface coating is generally used to improve the surface of the positive electrode material. The coated chemically inert material effectively isolates the positive electrode material from the electrolyte, avoids the reaction of high-v...

AI Technical Summary

Problems solved by technology

[0002] Nickel-cobalt-aluminum ternary lithium-ion battery cathode materials are widely used in IT products and new energy vehicles due to their high energy density and relatively simple preparation process. However, lithium nickel-cobalt aluminate (LNCA) has poor structural stability Good, high-priced nickel is easy to react with the electrolyte, causing the electrolyte to decompose and release gas, causing great harm to the cycle life and safety of the material; to solve the above problems, surface coating is generally used to improve the surface of the positive electrode material. The coated chemically inert material effectively isolates the positive electrode material from the electrolyte, avoids the reaction of high-valent nickel ions and the electrolyte, and maintains the stability of the positive electrode and electrolyte, thereby improving the cycle life and safety performance of the material

[0003] AlPO 4 The coating has a significant effect on improving the stability of the positive electrode material and electrolyte, but at the same time, because the coating is generally non-electrochemically active substances, it will have a certain impact on the specific discharge capacity of the material. If the coating is too large High, the discharge capacity will be significantly reduced. If the coating amount is insufficient, the stability of the material will not be effectively improved. Therefore, the coating material can be thinly and uniformly coated on the surface of the positive electrode material to achieve discharge specific capacity and stability. An important factor for the balance of properties, and in the process of coating, it is necessary to prevent AlPO 4 precipitation

Images