Leaching & electrochemical purification of mixed industrial LFP- & NMC type lithium-ion battery waste.

The use of Li-ion batteries for electricity on the go and electrification of transport is rapidly increasing, resulting in rising pressure on critical raw materials (CRMs) such as Li, Co and Mn. However, commonly applied recycling routes have a large environmental impact, as extensive use of chemicals such as H2SO4 and H2O2 is required to achieve high dissolution rates. In addition, battery chemistries such as LFP (LiFePO4) have low intrinsic value, thereby limiting their recycling incentives. This research presents a recycling route for industrially pre-treated black mass (BM) from spent NMC (LiNi x Co y Mn z O2) and LFP batteries, combining a synergistic leaching step under mild acidic conditions (1 mol L-1 H2SO4) with subsequent removal of Fe, Al and Cu through a novel process that combines precipitation with electrochemical purification. Unlike conventional processes, the proposed simultaneous leaching resulted in the complete dissolution of Li, Co, Ni, Mn, and Fe without external reducing agents using industrially representative LiB-waste. A subsequent precipitation step, followed by electrodeposition of Cu and electrochemical oxidation of Fe2+ to Fe3+ using custom designed electrodes, was investigated at pH 2, 3, and 4. The best results were obtained by performing the electrochemical purification at pH 4. Overall removal efficiencies of 49% Al, 93% Fe and 73% Cu were achieved, of which Fe was mostly recovered as FePO4, while Ni, Co, and Mn co-precipitates with impurity levels as low as 0.1-0.6 wt% were obtained at pH > 8, leaving only Li in solution. This work presents a significant step towards more eco-friendly LiB-recycling, demonstrating the feasibility of a versatile, electrochemical purification approach.