Direct regeneration of cathode materials from spent lithium iron phosphate batteries using a solid phase sintering method

Abstract

A direct regeneration of cathode materials from spent LiFePO₄ batteries using a solid phase sintering method has been proposed in this article. The spent battery is firstly dismantled to separate the cathode and anode plate, and then the cathode plate is soaked in DMAC organic solvent to separate the cathode materials and Al foil at optimal conditions of 30 min at 30 °C and solid liquid ratio of 1 : 20 g ml⁻¹. XRD and SEM results of the spent LiFePO₄ after separation show that there are some impurity phase components and irregular morphologies with many agglomerations. The spent materials are regenerated at appropriate temperatures with doping of new LiFePO₄ at different ratios. Battery capacities from regenerated LiFePO₄ can reach over 120 mA h g⁻¹ at 0.1C discharge conditions, especially with the highest value of 144 mA h g⁻¹ with a doping ratio of 3 : 7 at 700 °C. The rate capabilities and cycling performance of batteries made from regenerated LiFePO₄ with doping at 600 °C and 700 °C are generally better than those at 800 °C. All the performances of batteries made from regenerated LiFePO₄ with pure phase and uniform morphology can meet the basic requirements for reuse.