Recovery of Ni-Co alloy, MnO2, graphite and Li2CO3 from spent ternary lithium-ion batteries through three-compartment electrolysis

Abstract

The separation and recovery of key metals are essential for the sustainable recycling of spent lithium-ion batteries (SLIBs). In this paper, a three-compartment electrolysis is proposed to achieve the direct separation of multiple components in a one-step process through the application of an electric field. In the middle compartment, lithium nickel cobalt manganese oxide (NCM) material dissolves and separates from graphite. Simultaneously, Ni-Co alloy deposits at the cathode, while MnO₂ synthesizes at the anode. Additionally, Li⁺ concentrates and subsequently precipitates as Li₂CO₃ through chemical precipitation in the electrolyte. As a result, the leaching efficiencies of Ni, Co, Mn, and Li in spent lithium nickel cobalt manganese oxide (SNCM) materials reach 94.30 %, 90.78 %, 98.19 %, and 94.33 %, respectively, in the middle compartment within 6 h at 80 ℃. Meanwhile, the recovery rates for Ni, Co, and Mn are 87.22 %, 81.50 %, and 48.89 %, respectively. The proportions of Ni and Co in the Ni-Co alloy are 33.42 % and 44.82 %, respectively. Li₂CO₃ with a purity greater than 95 % is recovered from the electrolyte through simple concentration and precipitation. For every 1 kg of SNCM electrode powder recovered, the carbon emissions from the three-compartment electrolysis and electrolyte reuse are 3.81 kg CO₂ eq. and −3.47 kg CO₂ eq., resulting in economic benefits of $0.25 and $2.06, respectively. This approach enables the simultaneous separation and recovery of multiple metals in a single step, addressing the growing demand for critical energy metals.