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

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 Fe3O4 QDs (SC-Fe3O4) 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 Fe1-xS QDs (SC-Fe1-xS) 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.