A green strategy for selective recovery of valuable metals from spent lithium-ion batteries through a waste graphite-assisted sulfation process

Abstract

The worldwide increase in spent lithium-ion batteries (SLIBs) raises environmental concerns and leads to the waste of strategic resources. Conventional battery recycling processes including pyrometallurgical and hydrometallurgical methods face bottlenecks of excessive energy consumption or toxic wastewater generation. Furthermore, the process of starting with spent battery cathodes and ultimately producing lithium/cobalt salts instead of regenerated cathodes is unsustainable. Here, a green strategy called waste cathode–anode material sulfation roasting (WCASR) is proposed for the efficient and selective separation of lithium and cobalt, enabling the sustainable regeneration of LiCoO₂. The conversion mechanism of WCASR was elucidated through thermodynamic analyses and multiscale characterization. Incorporating a waste graphite anode material as a reducing agent can accelerate the separation of lithium and transition metal elements from LiCoO₂ during the sulfation roasting process. High-value lithium and cobalt can be efficiently separated into Li₂SO₄ and Co₃O₄ at a lower calcination temperature, which can subsequently be utilized for the regeneration of the LiCoO₂ cathode material. The resulting LiCoO₂ cathode exhibited a high capacity of 131.4 mA h g⁻¹ at 1 C and a remarkable capacity retention of 88.47% after 100 cycles. Moreover, ecological and economic analyses showed that the consumption of chemicals and energy accounted for only 27% and 30% of that in the traditional metallurgical processes. The newly proposed green strategy achieved a dual breakthrough by simplifying the process and enhancing environmental friendliness, providing a sustainable approach for the reutilization of SLIBs.