A comprehensive approach for the recycling of anode materials from spent lithium-ion batteries: Separation, lithium recovery, and graphite reutilization as environmental catalyst

The effective recovery of valuables from anodes coming from spent lithium-ion batteries (LIBs) is of great importance to ensure resource supply and reduce the environmental burden for recycling. In this work, a simple and low energy consumption roasting method was proposed by employing low-temperature eutectic NaOH-KOH as reaction medium, in order to simultaneously separate graphite from Cu foils, extract lithium from it and set it up for reuse as environmental catalyst through one-step water washing process. Our results show that polyvinylidene difluoride (PVDF) was effectively deactivated due to dehydrofluorination/carbonization at a relatively low temperature and short time (150 °C, 20 min) when a mass ratio of 1:1 for eutectic NaOH-KOH to spent LIBs anodes was used, yielding 97.3 % of graphite detached. Moreover, a remarkable lithium extraction efficiency of 93.2 % was simultaneously obtained. Afterwards, the reusability of the recycled graphite was tested by employing it as a catalyst for the treatment of a contaminant organic dye (Rhodamine B) in the presence of NaClO. Our results show that a superior NaClO activation was obtained with the addition of recycled graphite, being this fact closely associated to the abundant active sites formed during the long-term charging/discharging cycles in the original battery. The alkaline-mediated roasting process presented in this work presents an energy-saving scheme to efficiently recover useful components from spent anodes, whereas the reusability example highlighted a useful option for repurposing the severely damaged graphite as an environmental catalyst rather than disposing it in landfills, turning waste into a valuable material.