Comparison of two approaches for discharging LiFePO4 EV battery packs and comprehensive analysis of recovered cathodes for direct recycling purposes

Abstract

The recycling of spent Li-ion batteries has become a highly relevant research topic owing to increasing amounts of battery waste along with its toxic nature and significant content of valuable materials. Extensive research has been done on direct recycling of batteries with LiFePO₄ (LFP) chemistry, where the cathode active material (CAM) is collected and regenerated to be fit for use in new battery units. However, details on how the spent batteries should be handled, discharged and dismantled to collect the CAM are rarely discussed in research papers, despite being an integral part of any direct recycling application. Herein, we present a detailed description of two discharging methods of spent LFP batteries. Characterization of the CAM powders revealed the potential impact of the discharging method on CAM quality. Increased levels of copper and aluminum impurities in the CAM were observed after saline brine discharging, compared to discharging using an external electrical circuit. Considering the reduced number of process steps in the external circuit method, it is deemed more advantageous than the salt brine discharge method.