Enhanced Lithium- and Sodium-Ion Storage in an Interconnected Carbon Network Comprising Electronegative Fluorine

Abstract

Fluorocarbon (C-x F-y) anode materials were developed for lithium- and sodium-ion batteries through a facile one-step carbonization of a single precursor, polyvinylidene fluoride (PVDF). Interconnected carbon network structures were produced with doped fluorine in high temperature carbonization at 500-800 degrees C. The fluorocarbon anodes derived from the,PVDF precursor showed higher reversible discharge capacities of 735 mAh g(-1) and 269 mAh g(-1) in lithium- and sodium-ion batteries, respectively, compared to the commercial graphitic carbon. After 100 charge/discharge Cycles, the fluorocarbon showed retentions of 91.3% and 97.5% in lithium (at 1C) and sodium (at 200 mA g(-1)) intercalation systems, respectively. The effects of carbonization temperature on the electrochemical properties of alkali metal ion storage were thoroughly investigated and documented. The specific capacities in lithium- and sodium-ion batteries were dependent on the fluorine content, indicating that the highly electronegative fluorine facilitates the insertion/extraction of lithium and sodium ions, in rechargeable batteries.