Preparation method of titanium-doped lithium iron phosphate cathode material

Abstract

The invention discloses a preparation method of a titanium-doped lithium iron phosphate cathode material. The preparation method comprises the following steps: by using a lithium source compound, a phosphorus source compound, an iron source compound and metallic titanium as raw materials, evenly mixing the raw materials and melting the mixture in a melting furnace at high temperature to obtain a mixture; performing water quenching on the mixture into particles; grinding and dispersing the particles and a carbon source compound together to ensure that the particle size reaches the Fineness index of D90 being less than or equal to 0.2 micron; making powder in a spray drying method, and calcining the powder for 40 to 300 minutes in an atmosphere furnace of 600 to 800 DEG C; performing coolingto obtain the lithium iron phosphate cathode material. By adopting a high-temperature melting method, the uniformity of the lithium iron phosphate cathode material is improved; by introducing metallic titanium powder, Fe<3+> in a melt solution is reduced into Fe<2+> at high-temperature melting state, and generated Ti<4+> is doped into a lithium iron phosphate structure, and the electron conductivity of the lithium iron phosphate cathode material is improved through formation of vacant positions; the specific surface area is reduced by means of grinding and dispersion as well as carbon coating, and the tapping density of the lithium iron phosphate cathode material is improved. According to the preparation method disclosed by the invention, crushing and integration are not needed, so that the original sphericity can be maintained and technological processes are also simplified.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a method for preparing a titanium-doped lithium iron phosphate cathode material. Background technique [0002] Since the lithium iron phosphate cathode material has an olivine structure, it can reversibly intercalate and remove lithium, and has high voltage, high specific capacity, good cycle performance, stable electrochemical performance, low raw material prices, and environmental friendliness. One of the best cathode materials for preparing long-life, high-power, high-safety, low-cost lithium-ion power batteries or energy storage batteries. However, lithium iron phosphate cathode materials have some inherent structural defects: lithium ion migration rate, electronic conductivity and tap density of the material are all low. [0003] At present, in order to improve the poor conductivity of synthetic materials, many synthesis processes use high-temperature solid-state-carbot...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of low specific capacitance and tap density of the lithium iron phosphate positive electrode material due to the low electrical conductivity and tap density of the above-mentioned lithium iron phosphate positive electrode material and the complicated preparation process. The invention provides a preparation method of titanium-doped lithium iron phosphate cathode material

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