Enhancing the cycle life of recycled graphite materials from spent lithium-ion batteries via conductive polymer coating

In recent years, lithium-ion batteries have been widely used in electric vehicles and electronics. Among most commercial lithium-ion batteries, graphite is used as an anode material because it ensures high voltage coupled with lithium-ion cathode and high capacity. Spent lithium-ion battery anode is difficult to be recycled and revitalized, because the pyrometallurgy process only works well with metal oxide cathodes. In addition, even if the spent graphite were recovered, it could not be directly applied for new electrode fabrication due to its poor interface conductivity and mechanical disintegration. In this study, we introduced an innovative method for the regeneration and reuse of spent graphite anode materials. Our method purified and revitalized graphite particles by removing legacy solid electrolyte interphase (SEI) and constructing an artificial, elastic, and conductive polymer-based SEI layer. This polymer has a conjugated polyfluorene backbone that significantly improves the electrical conductivity and mechanical durability of the regenerated graphite particles. Electrochemical tests involving both half-cells and full-cells revealed that regenerated graphite coated with HOS-PFM showed a remarkable increase in cycle life and demonstrated the ability to sustain high C-rate charging and discharging. We suggest that this method could provide a simple and effective solution for reclaiming and reusing graphite anodes in battery manufacturing. • A simple and sustainable method is developed to recycle spent graphite. • Purified graphite particles are coated with a conductive polymer HOS-PFM. • HOS-PFM improves electrical conductivity and mechanical strength of graphite. • Regenerated graphite with HOS-PFM show improvement in cycle life. • HOS-PFM prevents excessive SEI formation on regenerated graphite particles.