Process for producing iron phosphate for producing iron lithium phosphate material

Abstract

The invention discloses a preparation method of iron phosphate for preparing lithium iron phosphate material, and relates to heavy metal phosphate. The steps of the method are as follows: analyticallypure soluble molysite is dissolved in distilled water, thereby being prepared into 0.05 to 5 M water solution, and being added with anionic surface-active agent with the mass being 0.01 to 3 percentof the mass of the molysite, then analytically pure phosphoric acid is added according to the mol ratio of Fe<3+>:PO4<3-> equal to 1:0.8 to 1.2 and stirred, alkaline solution with the concentration of1 to 9 M is slowly added in stirring state, the adding time is more than 1 hour until the Ph value of the solution reaches 6 to 7, the deposited matter of iron phosphate is filtered, the filtered iron phosphate is cleaned for 3 to 5 times with distilled water with the 2 to 5 times weight of the iron phosphate, the iron phosphate is dried in the range of 60 to 90 DEG C under a vacuum condition, and the finished FePO4.2H2O powder is gotten. The iron phosphate product with two crystal water prepared by the invention has high reaction activity, and the performance of the lithium iron phosphate material prepared with the iron phosphate product is superior to the lithium iron phosphate material prepared with the commercial iron phosphate product.

Description

technical field [0001] The technical solution of the present invention relates to heavy metal phosphates, in particular to a method for preparing iron phosphate used for preparing lithium iron phosphate materials. Background technique [0002] Lithium iron phosphate has high theoretical capacity (170mAh / g), high working voltage (voltage platform around 3.5V), appropriate mass density (3.64g / cm 3 ), small self-discharge, LiFePO at low current density 4 Li in + Almost 100% intercalation / deintercalation, long cycle life, good cycle performance, no memory effect, low price, good thermal stability, and environmental friendliness, etc., are expected to replace the high-cost LiCoO 2 Become a new generation of lithium-ion battery cathode material. [0003] At present, the solid-state reaction method is the main method for the synthesis of lithium iron phosphate materials. In the preparation methods of lithium iron phosphate materials disclosed in CN 1581537, CN 1753216, CN 19584...

AI Technical Summary

Problems solved by technology

The ferric phosphate material with two crystal waters produced by the method of the present invention has a crystal structure similar to lithium iron phosphate, which overcomes the problem that commercially available ferric phosphate products have a complete grain structure, low reactivity, and lithium ion It is very difficult to diffuse in it, and it is difficult to insert lithium ions in the subsequent sintering process to form the shortcomings of lithium iron phosphate crystals suitable for lithium-ion battery cathode materials, thereby improving the performance of lithium iron phosphate materials