Hard carbon derived from rice husk as anode material for high performance potassium-ion batteries

Due to the rapid development of the large-scale electric energy storage systems (EESs) and the electric vehicles (EVs), potassium-ion batteries (KIBs) are known as promising alternatives for lithium-ion batteries (LIBs). Here, we synthesized hard carbon via carbonization of rice husk and first studied its electrochemical performances as anode material of KIBs. The hard carbon shows a high reversible capacity of 244.99 mAh·g−1 at the current density of 30 mA·g−1 and stable cycling performance. Even at the high current density of 500 mA·g−1 it still exhibits 103.77 mAh·g−1 after 500 cycles. This work not only provides the application of biomass-based hard carbon as a promising anode material for practical KIBs, but also furthers the knowledge to understand the storage mechanism of K+ in the hard carbon.