Recycling\nof Spent\nGraphite from Lithium-Ion Batteries\nfor Aqueous Zn Dual-Ion Batteries

As\nlithium-ion batteries (LIBs) become more widespread,\nthe number\nof spent LIBs gradually increases. Until now, recycling of spent LIBs\nhas mainly concentrated on high-value cathodes, but the anode graphite\nhas not yet attracted wide attention. In this work, spent graphite\nfrom LIBs was oxidized to graphene oxide and then thermally reduced\nto reduced graphene oxide (RGO), which serves as the cathode of aqueous\nZn dual-ion batteries (ZDIBs). The thermal reduction process enables\nRGO with a large layer spacing and porous structure, which increase\nthe anion insertion sites and transfer kinetics. As a result, the\ncorresponding battery exhibits a high specific capacity of 96.82 mAh\ng<sup>–1</sup> at 1 A g<sup>–1</sup>, superior rate\ncapability, and a high capacity retention rate of 80% after 2000 cycles.\nMoreover, RGO gradually transforms into a long-range disordered structure\nduring the cycling process, which provides more transport routes and\nactive sites for anion insertion and thus leads to the increase of\ncapacity. This work combines the recycling of spent graphite with\naqueous ZDIBs, realizing the high-value use of spent graphite.