(335c) Evaluation of Temperature Effect on Graphite Anodes for K-Ion and Li-Ion Batteries
Graphite remains as the ubiquitous anode material for Li-ion batteries, due to its good cycling stability arising from low-strain Li intercalation storage mechanism. In recent years, it has seen novel implementation as anode material for the sustainable and low-cost K-ion battery system, where a similar intercalation mechanism results in a specific capacity of 279 mAh g-1 correlating to the KC8 stage-one structure, with voltage plateaus near 0.2 V (vs. K+/K). All investigations thus far on the electrochemical performance of this system, however, have been conducted only at room temperature, limiting the knowledge of its commercial viability. In this study, we evaluate the effect of operating temperature on electrochemical performance in graphite and compare the Li-ion and K-ion intercalation mechanisms and behavior. Investigations into cell ageing, voltage hysteresis, rate capability, and electrochemical impedance are carried out over the operating temperature range 0°C - 40°C, with kinetic parameters determined for solid-state diffusion, charge-transfer resistance, structural alterations, and solid electrolyte interphase (SEI) layer resistance. These results provide insight into the energetics of K+ intercalation in graphite, and the electrochemical performance across a wide temperature range for the emerging K-ion battery chemistry.