Enhanced K+-Solvent Co-Intercalation Into Regenerated Spent Graphite a High-Rate Capable Anode for Potassium-Ion Batteries at Different Temperatures

Globally accelerating the requirement for ecologically sound and economically efficient energy storage prompted interest in battery technologies. Since the origin, lithium-ion batteries (LIB) dominated with high energy density and mature infrastructure; however, given the scarcity of lithium resources and rising cost, there has been a driving force to explore alternatives like sodium-ion battery and potassium-ion battery technologies. Among these, KIBs offer high power density, favorable K⁺ ion diffusion kinetics, wider range of voltage at higher potential, eliminates the formation of intermetallic compounds, is abundant and also cost-effective, unlike LIBs. KIBs can use industrial standard graphite as anode unlike NIBs but both behave similarly during ion-solvent co-intercalation. Eventually reached with versatile electrode, graphite, as anode exhibits reversible potassium intercalation and charge storage mechanism with structural constraints of larger potassium-ions and lacks stability. Herein, we introduced graphite anodes recycled from spent LIBs, regenerated as anodes for KIBs-propounding a circular economy. The optimized sample tested with an ether-based electrolyte exhibited 107 mAh/g capacity at 5 A/g and was stable for 1000 cycles at room temperature. This sustainable material suitably tailored, exhibits good electrochemical performance at both room and low temperatures. Also, the kinetics of co-intercalation mechanism was investigated using electrochemical impedance spectroscopy, ex situ x-ray diffraction and transmission electron microscopy. To a greater extent, the work highlights the positive outcomes of usage of spent graphite in advanced resource-efficient energy storage solutions. This idea keeps away resource exploitation, environmental contaminations and economic imbalances, reinforcing a sustainable circular economy.