Porous Structures Formed by Fluorine-Doped Reduced Graphene Oxide Sheets as High-Performance Anodes for Potassium-Ion Batteries

Abstract

Polyvinylidene fluoride pyrolysis into fluorocarbon (CF) and the insertion of reduced graphene oxide (RGO) nanosheets to form porous CF@RGO nanocomposites and their application as anode materials for potassium-ion batteries were investigated. First, RGO serves as a foundation for CF nanoparticles and provides a good conductive network for improving the electrode conductivity and capacity of the electrode. In the meantime, it also functions as a buffer against volume changes during charging and discharging. Fluorine-doped mesoporous carbon can not only improve electrical conductivity and enhance long-term cyclic stability but also increase rate capacity. In addition, the higher electron cloud density of CF nanoparticles further enhances electronic interactions and provides more active sites for K+ embedding in the charge and discharge processes to maintain structural stability. Synergy between RGO and CF effectively relieves electric stress and provides a pathway for rapid electron and ion transport. The sheet structure of porous CF@RGO contributes to the stability of the SEI film, triggering excellent material retention and improving the electrochemical performance. Therefore, the porous CF@RGO electrode exhibits a high reversible capacity of 209.2 mA h g–1 after 200 cycles of 0.1 A g–1 and a high stable capacity of 338.0 mA h g–1 after 1000 cycles of 0.5 A g–1. Porous CF@RGO composites remain structurally stable and agglomeration free after 1000 charge and discharge cycles. This work provides a new strategy to construct carbon materials for reversible potassium ion storage.