Nonmetallic Se/N Co‐Doped Amorphous Carbon Anode Collaborates to Realize Ultra‐High Capacity and Fast Potassium Storage for Potassium Dual‐Ion Batteries

Abstract Heteroatom doping in carbon‐based anode materials is crucial to improve their capacity and promoting the practical application of low‐cost potassium‐ion batteries (KIBs). Herein, the selenium/nitrogen co‐doped amorphous carbon nanocluster (SeN‐ACN) anodes exhibit an ultra‐high reversible capacity of 621 mAh g −1 at 0.75 C (225 mA g −1 ) and a capacity retention of 93% after 2000 cycles at 5 C, which represent a remarkable achievement in potassium storage in nonmetallic doped carbon materials. This is attributed to the synergistic effects of Se/N co‐doping and their anchoring effects on potassium ions. As a proof of concept, a potassium‐based dual‐ion battery (K‐DIB), which consists of a SeN‐ACN anode and low‐cost graphite cathode, demonstrates a high reversible capacity of 118 mAh g −1 at 150 mA g −1 with a high cut‐off voltage of 5.2 V. Moreover, it presents excellent long‐term cycling performance, with 70% capacity retention after 500 cycles, among the best reported results of K‐DIBs.