Recovery of iron from titanium white waste for the preparation of LiFePO4 battery

Abstract

The recovery of iron from by-product ferrous sulfate in titanium white industry to prepare battery-grade FePO4 represents a promising approach to address the solid waste disposal issue while simultaneously providing a precursor for new energy battery. However, a critical challenge lies in the elimination of impurities during the purification and synthesis process to prevent decrease in electrochemical performance of the product. In this work, we propose a simple, clean and cost-effective route based on Al/Ti precipitation purification, followed by selective synthesis of FePO4·2H2O with coexisting divalent metal ions. The results demonstrate precipitation efficiencies of 98.3% and 99.9% for Al and Ti, respectively, and only 1.3% loss of iron under the optimal conditions during the purification separation process. The contents of impurity in the synthesized FePO4 from waste ferrous sulfate met the battery-grade standard. Furthermore, the synthesized LiFePO4 materials exhibited comparable electrochemical performance with that of commercial LiFePO4. In addition, the growth mechanism of FePO4·2H2O particles under high temperature and high acid environment was clarified, which was dominated by surface nucleation. This work provides a guidance for the utilization of iron resource from waste ferrous sulfate to prepare battery-grade LiFePO4, and may promote the recycling industries and clean production strategies in titanium field.