Interface-oriented engineering of bio-fermented bamboo-derived carbon via F/O doping for advanced sodium-ion storage

This study presents a sustainable F/O co-doped hard carbon (PD-F800) derived from panda excrement via NH 4 F-assisted hydrothermal doping for sodium-ion battery anodes. PD-F800 delivers a reversible capacity of 472.87 ± 5.1 mAh g −1 at 100 mA g −1 with an initial Coulombic efficiency of 66.2 ± 2.1 %, maintains 317.72 ± 4.0 mAh g −1 at 1000 mA g −1 , and retains 72.7 ± 3.3 % capacity after 1000 cycles. In situ XRD/Raman, EIS/DRT and GITT jointly indicate that F/O co-doping introduces non-bonded F states and regulates defect/interfacial chemistry, which lowers Na + adsorption/desorption barriers, increases Na + diffusion kinetics, and stabilizes an inorganic-rich SEI, thereby coupling fast surface-controlled storage with reversible interlayer/pore processes. This work establishes a safe, scalable route from waste biomass to high-performance anodes and clarifies the structure-interface-kinetics linkage enabling advanced Na-ion storage.