In Situ Composite Strategy of O/F-Dual-Doped Soft–Hard Carbon Anode Promotes Ultrafast and Highly Durable Potassium Storage Performance
Xiaoyi Lü, Junjie Zhou, Xingyu Li, Handong Peng, Chenglong Shi, Fangqing Liu, Le Huang, Zhipeng Sun
Abstract
Soft–hard carbon has been regarded as a suitable anode material for potassium-ion batteries (PIBs) due to synergistic effects between hard carbon (HC) and soft carbon. However, the cost-effective and precise structural control of these carbons remains a significant challenge. In this study, O/F-dual-doped soft–hard carbon (OFPC) composite materials with a porous honeycomb-like structure are simply synthesized by using an in situ, low-temperature pyrolysis strategy. It is observed that the outer wall of HC is uniformly and closely wrapped by a soft carbon layer, ensuring excellent electrical conductivity and charge-transfer kinetics. Furthermore, O/F codoping in soft–hard carbon can preserve rich defects and active sites while enlarging the interlayer spacing (0.413 nm). As an anode for PIBs, OFPC demonstrates obviously reducing polarization, long-life cycling stability (93% capacity retention rate over 3000 cycles at 1 A g –1 ), and rapid K + transport kinetics (reversible capacity retention of 47.1% at 5 A g –1 compared to that at 0.1 A g –1 ). Particularly noteworthy is the continuous structural self-optimization during the cyclic charge/discharge process to adapt to the large radius of K +, which can be monitored and quantified by kinetic analysis and in situ/ex situ Raman spectra. This work provides a facile strategy to develop promising carbon anodes for advanced PIBs.