Correlation Between Microstructure and Potassium Storage Behavior in Reduced Graphene Oxide Materials.

Potassium-ion batteries (PIBs) are considered to be potential alternatives to the conventional lithium-ion batteries (LIBs) due to the similar work mechanism and abundant potassium (K) resource. However, it still remains challenging to directly apply commercial graphite anodes for PIBs owing to the large K ions, which may impede the electrochemical intercalation of K ions into graphite interlayer and result in poor cyclic stability and rate capability. The reduced graphene oxide (rGO) has shown remarkable electrochemical performance as anode materials for PIBs due to the fact that rGO possesses more active sites with an enlarged interlayer distance. Understanding the microstructure of rGO is crucial for optimizing its K ions storage capabilities. Herein, it is revealed that the K ions storage behavior of rGO is strongly dependent on thermal treatment temperature on account of the difference in microstructure. The rGO graphitized at 2500 °C exhibits a superior long-term cyclic stability for stable 2500 cycles due to the expand interlayer distance and the unique graphite-like structure in a long range, enabling it to endure the huge volume change during uninterrupted K ions intercalation/de-intercalation processes. Keywords: reduced-Graphene Oxide, potassium-ion battery, anode, graphitization.