Temperature dependent electrochemical performance of graphite anodes for K-ion and Li-ion batteries

The electrochemical behavior of graphite anode for potassium-ion batteries (KIBs) is investigated in detail over varying operating temperatures (0-40 degrees C) with comparisons made to lithium-ion batteries (LIBs). Three main categories of cell performance are analyzed and evaluated, namely, kinetics, aging, and polarization. At 10 degrees C and below, the KIBs exhibit poor rate capability, which can be attributed to the decreased solid-state diffusion coefficient, and the amplified charge-transfer and SEI resistances. In comparison to LIBs, KIBs exhibit rapid cell aging at elevated temperatures, owing to augmented SEI growth induced by the significant volumetric change of graphite during potassiation. 3-electrode cell studies reveal the dramatic polarization of K metal at 0 degrees C (161 mV), while the extreme reactivity of K metal causes a severe rise in impedance from cell storage at 50 degrees C. A full cell system comprising Prussian blue cathode and graphite anode is evaluated, which removes the issues associated with the K metal counter electrode and enhances rate performance at 0 degrees C. These findings provide a thorough basis for understanding the temperature dependent behavior of graphite anode for KIBs and its performance concerns at low and elevated temperatures.