Cobalt and lithium recovery from spent LiCoO2 using a free-standing potassium zinc hexacyanoferrate/carbon cloth composite electrode

Abstract

Rapid rejuvenation and extensive utilization of mobile electronic devices lead to the excessive accumulation of waste lithium-ion batteries (LIBs), specifically spent LiCoO₂ cathode materials. Considering the shortage of metal resources and the surging price of raw materials in the battery industry, an efficient strategy for selectively extracting valuable metals from spent LiCoO₂ is urgently required. Herein, nanocube-like potassium zinc hexacyanoferrate (denoted as KZHCF) was successfully fabricated on a carbon cloth (CC) substrate for selective Co²⁺ adsorption from a spent LiCoO₂ cathode via the combination of simple electrodeposition and hydrothermal treatment. Under optimal operational conditions, 98.6% of Co²⁺ was effectively extracted within 120 min at a constant potential of −0.4 V (vs. Ag/AgCl) with the CC/KZHCF composite as the working electrode, accompanied with a Co²⁺ electrosorption capacity of 130.9 mg g⁻¹. Further, lithium ions in the electrolyte were separated and recovered in the form of Li₂CO₃ via simple chemical precipitation, highlighting the feasibility of the developed electrochemical system toward cobalt and lithium recovery. Significantly, the CC/KZHCF electrode materials could be regenerated through simple potential inversion, while adsorbed Co²⁺ ions were facilely desorbed from the electrode surface and recovered as Co(OH)₂. This work will provide a meaningful guidance for the separation and recovery of various metals from waste LIBs.