Preparation method of compound phosphate-series positive electrode material for lithium-ion battery

Abstract

The invention relates to a preparation method of a compound phosphate-series positive electrode material for a lithium-ion battery. The method comprises the following steps: preparing a solution from a soluble bivalent iron salt and a soluble transition metal nickel salt, cobalt salt or manganese salt, and then adding an acid and urea to prepare a mixed solution; adding a precipitant to the mixed solution for reaction and preparing a mixed oxalate precursor; and carrying out ball-mill mixing on the precursor, a lithium source and a phosphorus source evenly and preparing the compound phosphate-series positive electrode material for the lithium-ion battery in an inert or weak reductive atmosphere. The used aqueous urea solution is slowly hydrolyzed under the acid, alkali and urease catalysis or heating conditions. The urea hydrolysis rate is low and the hydrolysis product is simple and easy to volatilize, so that the aqueous urea solution can be applied to homogeneous precipitation of elements and ions. The first charge and discharge specific capacity of the obtained product at a room temperature and 0.1C rate can reach about 160mAh / g; and the compound phosphate-series positive electrode material is good in cycle performance and charge and discharge performance.

Description

technical field [0001] The invention relates to a preparation method of a composite phosphate series lithium ion battery cathode material which is doped with metal ions by a co-precipitation method, and belongs to the technical field of material preparation. Background technique [0002] In recent years, the research and development of lithium-ion batteries have made gratifying achievements, especially the improvement of the performance of the negative electrode and the development of the electrolyte system have achieved great results, but the research on the cathode materials of lithium-ion batteries appears to be relatively lagging behind, which has become a constraint for lithium-ion batteries. The bottleneck of battery market and application expansion. Lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt composite oxide, lithium manganese oxide, lithium vanadate and other positive electrode materials have always been a hot spot in the field of positive elect...

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Problems solved by technology

[0007] In the method described in this application, uneven mixing of the precipitating agent and the salt solution and uneven thickness of the precipitated particles are likely to occur, which is not conducive to obtaining a precursor with a stable composition ratio, uniform particle size distribution, and good consistency, and ultimately leads to the synthesis of mono- or Poor performance of cathode materials for multi-component composite phosphate lithium-ion batteries