Molten salt-mediated separation and recovery of valuable elements from spent LiFePO4 black mass

Spent LiFePO 4 (LFP) battery black mass (SLFPB) recycling is important and faces significant challenges due to complex composition. This work presents a novel molten CaCl 2 -based leaching-electrolysis method for comprehensive valuable component recovery. This process yields recovery percentages exceeding 95 % for Fe, Cu, and P, 87 % for graphite, and 70 % for Al, while enriching Li in the melt. The molten salt shows potential for cyclic operation. Mechanistically, LiFePO 4 and FePO 4 in SLFPB react with molten CaCl 2 to form metal chlorides, Ca 5 (PO 4 ) 3 Cl, and Ca 2 PO 4 Cl intermediates, which subsequently dissociate into soluble ions. Most Fe escapes as FeCl 2 vapor. Graphite, due to its lower density, floats to the melt surface. The distinct thermodynamic properties of Fe 2+ , Cu + , and PO 4 3– allow their separation and recovery as metals and P 4 through two-step electrolysis. Differences in leaching and volatilization rates leads to the accumulation of Li. This approach provides a simple pathway for comprehensive SLFPB recycling.