Graphite Recovery in Spent Lithium-Ion Batteries

Abstract

Due to their high specific energy density (Wh/kg), high volumetric energy density (Wh/L), and long cycle life, lithium-ion batteries (LIBs) are being widely used. With the rapid growth of demands on LIBs these years, recycling methods are developed to solve the shortages of supply for rare metal cathode materials, especially Li and Co. However, not being evaluated as high-value material, graphite in spent LIBs always gets neglected and is burnt or downcycled which consequently generates CO2 gas as an inescapable result. Recent reports show the market demand for energy storage from Li-ion batteries will reach 400 GWh in the year 2022, which required nearly 3 million tons of graphite, also it is estimated that 3 billion batteries are thrown away each year in America. Considering the raw material making graphite is organic materials from nature with an irreversible process, a vicious circle can’t be broken if graphite doesn’t get recycled. Remarkably, our group has developed a novel closed-loop hydrometallurgical process for recycling end-of-life Li-ion batteries. After developing acid leaching and alkaline sintering methods, recycled graphite with an ultra-high purity (over 99.99%) is obtained for the first time in the hydrometallurgical process. Being successfully scaled up to the industrial level, it’s proved to be a green and high-efficient method in battery recycling. Further economical and efficient modification means are followed, recovering the structure, and improving the stability of recycled graphite to approach the commercial standard. In summary, our research provides a novel maneuver to fully purify and recover recycled graphite, which has great potential to be commercialized.