Method for equal molar preparation of lithium iron phosphate by hydrothermal method

Abstract

The invention discloses a method for equal molar preparation of lithium iron phosphate by a hydrothermal method. The method comprises the following steps: (1) dissolving weighed iron phosphate stabilizer into deoxidized distilled water, stirring the deoxidized distilled water and adding an iron ferrous source to form a mixed solution A; (2) dissolving weighed LiH<2>PO<4> at the ratio of Fe<2+> to Li<+> being 1 to 1 to form a solution B; and (3) mixing the mixed solution A with the solution B evenly, adding the mixture to a high-pressure reaction kettle, adjusting the pH to be 6-8, introducing an inert gas, heating the reaction kettle to 160-200 DEG C for heat preservation for 4-6 hours in a wave mode, naturally cooling the reaction kettle to a room temperature, carrying out filtering, washing and vacuum drying to obtain a cathode material LiFePO<4>. The cathode material LiFePO<4> prepared by the method is excellent in performance; and the specific discharge capacity at 0.2C reaches 152mAh / g.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to a method for preparing lithium iron phosphate in equimolar quantities by a hydrothermal method. Background technique [0002] In recent years, the application of lithium-ion batteries in the field of new energy has attracted more and more attention. Subsequently, as one of the core parts of lithium-ion batteries, cathode materials have become a research hotspot. The lithium iron phosphate material has the advantages of wide sources, low cost, low toxicity, easy recycling, good safety performance, long service life and high specific capacity, and is currently one of the most popular and reliable candidate cathode materials. [0003] At present, in many preparation methods and electrochemical performance improvement of lithium iron phosphate, solid-phase method, sol-gel method, hydrothermal method, carbon coating, metal ion doping, etc. occupy a...

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Problems solved by technology

For example: wang et al. (ElectrochemActa, 2005, 50, 14) used a solid-state reaction method to prepare Fe-site-doped cathode material LiFe 0.9 Mg 0.1 PO 4 ; Jin et al. (JPowerSources, 2008, 178) synthesized LiFePO by hydrothermal method 4 , with LiOH, FeSO 4 , H 3 PO 4 As raw material, the molar ratio is 3:1:1, first mix phosphoric acid and ferrous sulfate, add a small amount of distilled water to stir, then add lithium hydroxide solution to the mixed solution, stir and then transfer to the reaction kettle, in the dry box at 180 Heating at ℃ for 5 hours; in this method, lithium source: iron source: phosphorus source is 3:1:1, a large amount of lithium source in the solution neutralizes redundant anions, resulting in waste of raw material costs, and metal iron ions are easy to react with phosphate Agglomeration occurs and precipitates at the bottom of the autoclave, and insufficient contact with lithium ions leads to high content of reaction impurities, high cost and complicated operation

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