Facile fabrication of F-doped biomass carbon as high-performance anode material for potassium-ion batteries

Abstract

Heteroatom doping can effectively improve the electrochemical activity of carbon materials. In this paper, three kinds of fluorine-doped biomass carbon are synthesized using industrial hemp core as the precursor and Poly tetra fluoroethylene (PTFE), Diethylaminosulphur trifluoride (DAST) and Hydrofluoric acid (HF) as fluorinating agents, respectively. Among them, the PTFE-treated biomass carbon (PTFE-CHEMP) is wrapped by fluorine-containing nanotubes, which has the most defects, the most F doping amount and the optimum pore size, and is beneficial to the adsorption of K+. When used as the anode of potassium ion batteries (PIBs), the PTFE-CHEMP electrode can provide an average reversible capacity of 369.6 mAh g−1 (200 mA g−1) in 500 cycles. Even at a high current of 2000 mA g−1, it can still provide an excellent rate capability of 229.3 mAh g−1. Kinetic analysis verify that its excellent rate performance comes from the K+ storage mechanism dominated by surface-driven behavior. In addition, the constant current intermittent titration technique (GITT) shows that it still has the storage capacity for K+ at high potentials. This work not only provides a reference for subsequent research on fluorine-doped biomass carbon, but also provides a potential solution for the production of low-cost, high-capacity PIBs anodes.