Nanoconfining red phosphorus within MOF-derived hierarchically porous carbon networks for high performance potassium storage

Abstract

Red phosphorus is a kind of promising anode material for potassium-ion batteries owing to its ideal theoretical capacity. Unfortunately, its wide application in potassium storage is greatly limited by the poor electrical conductivity and severe volume expansion in the electrochemical reaction process of red phosphorus. Combining red phosphorus with a porous carbon substrate is a potential approach to enhance the potassium storage performance of red phosphorus, which can greatly promote the mass/charge transfer process and ease the volume change. Herein, hierarchically porous carbon networks were fabricated by two-step pyrolysis to confine red phosphorus (P@HPCN) with outstanding specific capacity, rate capability and cycling performance for potassium storage. The resultant anode material delivered reversible capacities of 461.8 mA h g⁻¹ at 0.1 A g⁻¹ after 100 cycles and 155.7 mA h g⁻¹ at 1 A g⁻¹ after 2000 cycles. Further experiments implied that the ideal electrochemical performance of P@HPCN could be associated with the synergism between red phosphorus and hierarchically porous carbon networks. Moreover, combining with theoretical calculations, we found that secondary calcination could effectively remove pyrrolic and pyridinic nitrogen from the porous carbon component, leading to a higher phosphorus loading.