Skin‐Inspired Conversion Anodes for High‐Capacity and Stable Potassium Ion Batteries

Abstract Conversion materials are promising anodes for meeting the emerging demand for high‐energy‐density potassium‐ion batteries. However, their application as anodes is challenging due to the irreversible volume expansion and the resulting structural failure during cycling. Inspired by the skin's structure, skin‐inspired carbon‐coated Fe 3 O 4 QDs (SC‐Fe 3 O 4 ) is synthesized, which exhibits excellent electrochemical performance with a capacity retention of 84.3% and a stable operation for >7 months. The same method is used to synthesize a series of other conversion material anodes with skin‐inspired structures. Notably, the skin‐inspired carbon‐coated Fe 1− x S QDs (SC‐Fe 1− x S) show a high reversible capacity of 506 mAh g −1 and a long stability of 1200 cycles. The research illustrates the universality and superiority of biomimetic strategies and provides new insights and directions for building high‐performance rechargeable batteries.