Hard carbon as a negative electrode material for potassium-ion batteries prepared with high yield through a polytetrafluoroethylene-based precursor

Abstract A new additive (polytetrafluoroethylene, PTFE) to typical sugar precursors for hard carbon (HC) preparation via hydrothermal carbonization has been proposed and investigated. The HC samples obtained from sugars (D-glucose and pectin) with and without PTFE were characterized with X-ray powder diffraction, Raman spectroscopy, scanning and transmission electron microscopy, energy-dispersive X-ray and electron energy loss spectroscopy, specific surface area measurements. Adding PTFE to sugars significantly improves the HC yield from