Preparation method of lithium iron phosphate coated with lithium iron oxide

Abstract

The invention discloses a preparation method of lithium iron phosphate coated with lithium ferrite. According to the method, the ferrous sulfate solution, the lithium hydroxide solution, the ammoniumdihydrogen phosphate solution and the titanyl sulfate solution are added into a high-pressure reaction kettle together, and then the hydrothermal reaction is carried out to obtain the slurry. A dispersing agent is added into the slurry, and a ferric chloride solution, an ammonium bicarbonate solution and a lithium hydroxide solution are merged and added into a base solution in a parallel flow manner. After the adding of above materials, the carbon dioxide is introduced and then the filtering is carried out. Obtained filter residues are heated and washed with pure water. A precursor is obtainedthrough drying and screening the residues and removing iron in the residues. The obtained precursor is calcined in an inert atmosphere, and the calcined material is subjected to smashing, screening and iron removing through the air flow to obtain lithium iron phosphate coated with lithium iron oxide. The method is simple and low in cost. The amorphous titanium-doped lithium iron phosphate is prepared through the hydrothermal method. After that, lithium iron phosphate coated with lithium iron oxide is obtained through precipitation. Finally, the lithium iron phosphate coated with lithium ironoxide is obtained through calcination. The obtained lithium iron phosphate is high in capacity and high in compaction density.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate coated with lithium iron phosphate, belonging to the technical field of lithium battery cathode materials. Background technique [0002] Lithium iron phosphate is a new lithium ion battery electrode material. It is characterized by large discharge capacity, low price, non-toxicity, and no environmental pollution. Countries around the world are successively realizing industrialized production. However, its tap density is low, which affects the capacitance. The main production method is high-temperature solid-phase synthesis, and the product index is relatively stable. The performance of lithium-ion batteries mainly depends on the positive and negative electrode materials. Lithium iron phosphate as the positive electrode material of lithium-ion batteries has only appeared in recent years. The domestic development of large-capacity lithium iron phosphate batteries was in July 2005....

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Problems solved by technology

[0003] However, the biggest disadvantage of lithium iron phosphate is its poor conductivity, so the conventional treatment method is to coat carbon, but after coating carbon, the compaction density of lithium iron phosphate will be low, so there is an urgent need for iron phosphate with higher compaction density and high capacity Lithium material

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