(183am) Direct Exfoliate Anode Graphite of Used Li-Ion Batteries into Few-Layer Graphene Sheets

Several hundred thousand tons of batteries are being produced annually, while the increasing spent lithium-ion batteries are polluting our environment. Precious metals in these wasted batteries are usually recycled, but recovery of the carbon anode materials of Li-ion batteries has not yet been realized. As the building block of all graphitic forms of carbon materials, graphene has attracted tremendous interest in energy storage devices, flexible electronics, solar cells, composite fillers, printed electronics, heterogeneous catalysis, etc. Sonication assisted liquid-phase exfoliation is the promising approach to prepare high quality graphene, but the low yield hindered the further development. Herein, we report a new strategy for recycling used anode graphite to prepare graphene sheets by sonication assisted liquid-phase exfoliation. Attributed to the reduced interlayer force after repeated charge-discharged cycles, the exfoliation efficiency of the used anode graphite was increased by 3 to 11 times relative to the natural graphite, with a highest mass yield of ∼40 wt%. The transmission electron microscopy (TEM) and atomic force microscopy (AFM) characterization revealed that the layer numbers of most the exfoliated graphene is 1–4 layers and their lateral sizes is over 1 μm. The Raman spectroscopy proved the high quality of the as-made graphene sheets. Besides, their conductivity can reach 9100 S m^–1, and their application in conductive ink was also demonstrated. More importantly, this technique cooperating with the precious metal recycling process may result in an environmental, high-efficiency and high value-add recycling technology in used batteries.