Spent graphite from lithium-ion batteries: re-use and the impact of ball milling for re-use

Abstract

The growing demand for lithium-ion batteries over the last decade, coupled with the limited and geographically confined supply of high-quality battery-grade graphite, underscores the importance of recycling graphite from spent batteries. Ideally, recycled graphite, already optimised for battery applications, can find application in new batteries, thereby reducing environmental impact and potentially delivering excellent performance. This study focuses on assessing the electrochemical performance of as-received and ball-milled recycled graphite obtained from two distinct battery waste streams. After 100 cycles at a current of 20 mA g⁻¹, capacities reach predominantly 313 mA h g⁻¹ for graphite recycled from LiCoO₂‖ graphite batteries and 242 mA h g⁻¹ for those recycled from LiNi_xMn_yCo_zO₂ (x + y + z = 1)‖ graphite batteries. Nonetheless, there remains a noticeable disparity in electrochemical properties between recycled graphite and commercial battery-grade graphite. One additional processing step is undertaken: ball milling for different durations, to modify particle size and morphology. As a result, after 3-hour ball milling, the average capacities increased by 10.5% and 20.2% for recycled graphite derived from LiCoO₂‖ graphite and LiNi_xMn_yCo_zO₂ (x + y + z = 1)‖ graphite batteries, respectively. This work clearly demonstrates that recycled graphite can be employed in second-life or batteries made from recycled materials and mechanochemical methods can be used to improve performance.