Preparation of FePO4•2H2O from LiFePo4 mixed with LiNixCoyMn1-x-yO2 waste material

Abstract

A method for preparing battery grade FePO4⋅2H2O from LiFePO4 and LiNixCoyMn1-x-yO2 mixed waste is proposed. The optimum leaching conditions included: temperature of 50°C, 3:1 liquid–solid mass ratio, 3.6 HCl/FePO4⋅2H2O mole ratio, 0.75 H2O2/FePO42H2O mole ratio, and 2 h reaction time. The solution obtained from the leaching waste material was diluted to a 1.0 M Fe concentration, then transferred to an 1 L beaker, where temperature, pH, complexing agent, ammonia addition rate and feeding mode were studied in order to determine their effects on the precipitation, particle size and morphology of FePO4⋅2H2O. High precipitation rate of Fe with low percentages of Al, Ni, Co, Mn in the FePO4⋅2H2O is achievable when precipitation is performed at a temperature of 85°C, pH of 2.0, and 20 g L-1 complexing agent. Furthermore, it was observed that a slow addition of ammonia and a flow feeding method contributed to the production of FePO4⋅2H2O, with small particle sizes and a flake morphology.

Keywords

• spent materials
• complexing
• preparation
• fepo4⋅2h2o