Constructing high-rate and long-life phosphorus/carbon anodes for potassium-ion batteries through rational nanoconfinement

The development of stable and durable phosphorus anodes for potassium-ion batteries (PIBs) has been retarded by a sluggish reaction kinetics and a notorious volume change with an ambiguous reaction mechanism upon cycling. Herein, the phosphorus nanoparticles have been rationally encapsulated into a commercial porous carbon through an evaporation-condensation strategy. Benefitted from the improved structural integrity/stability of electronically/ionically insulating phosphorus in a conductive/robust carbon matrix with abundant K+/electron migration channels, the phosphorus/carbon anode material with an appropriate phosphorus content (59.4 wt%) would achieve a large initial charging capacity of 744 mA h g−1 at 100 mA g−1 and a highly reversible capacity of 212 mA h g−1 at 3200 mA g−1 over 10,000 cycles with a superior rate capability of 287 mA h g−1 at 11,200 mA g−1. Simultaneously, the electrochemical importance of phosphorus loading on potassium storage capability of derived phosphorus/carbon composites was also uncovered. Critically, the noticeable capacitive intercalation/extraction of K+ in carbon nanostructure would significantly boost the charge storage process and promote the electrochemical performance of phosphorus/carbon anode. In terms of reaction mechanism for phosphorus/carbon anode, the active phosphorus would prefer to proceed a potassiation below 0.5 V upon discharging and a depotassiation below 1.0 V upon charging, accompanied by a reversible emergence/decomposition of K4P3. This novel study shedding lights on nanostructure design and mechanism clarification of phosphorus anode would contribute to the development of high-energy and long-life PIBs in practical applications.