Structure‐Optimized Phosphorene for Super‐Stable Potassium Storage

Abstract Few‐layer phosphorene is a promising anode material in potassium‐ion batteries, yet suffers from poor electronic properties and large volume expansion during the potassiation/depotassiation process. In this study, a facile synthesis method for a high‐performance phosphorene‐carbon nanotubes/polyaniline ((P‐CNTs)/PANI) composite is reported. The CNTs in the (P‐CNTs)/PANI composite serve as electron transport channels and improve the conductivity of phosphorene, while the PANI coating alleviates the structural degradation caused by the volume expansion of phosphorene. This results in super‐stable, high‐performance potassium storage. Structure‐optimized (P‐CNTs)/PANI anodes combined with a potassium bis‐(fluorosulfonyl)imide (KFSI)‐based electrolyte (3 m KFSI/dimethoxyethane) exhibits a high reversible capacity of 642.7 mAh g −1 at 50 mA g −1 and a maximum reversible capacity of 417.6 mAh g −1 at 500 mA g −1 during stable cycling. A capacity retention rate of 94% is observed after 500 stable cycles, while the average capacity decay rate per cycle is as low as 0.012%. Moreover, the anode exhibits an excellent rate performance of 147.8 mAh g −1 at 2000 mA g −1 . The results of the effect of the PANI coating show that (P‐CNTs)/PANI has a more stable structure and superior performance than P‐CNTs.