Fluorine doping of biomass-derived hard carbon for boosted sodium-ion storage

Mainstream hard carbon anode materials in sodium-ion batteries are frequently hindered by issues such as low kinetics for sodium-ion storage. In this work, we present a novel approach to overcome these key limitations by fluorine doping of wheat straw-derived hard carbon, which gives rise to a higher defect density, larger interlayer spacing and faster sodium-ion storage kinetics, when compared to the undoped hard carbon. As a result, the fluorine-doped hard carbon (HCF) exhibits an enhanced rate performance, higher specific capacity and optimized balance between slope and plateau capacity ratios, achieving a reversible capacity of 295 mAh g^-1 at 1.0 A g^-1. This study demonstrates that the intrinsic properties of hard carbon can be efficiently modified through heteroatom doping, offering a promising pathway for the development of high-performance anodes in sodium-ion batteries.