Phosphorous/Fluorine Co-doped Biomass-derived Carbon for Enhanced Sodium-ion and Lithium-ion Storage

Carbon from inexpensive biomass-based precursors have shown promise as anode materials for application in sodium/lithium ion battery technology. However, their practical implementation is marred by unreliable cycling stability and unimpressive initial coulombic efficiency. The electrochemical properties of such biomass derived carbon can be improved considerably by material engineering via suitable heteroatom doping. In this work, the effect of phosphorous and fluorine doping on naseberry seed derived carbon has been explored. The doping led to an increase in the specific capacity and rate performance of the modified bio-based carbon in comparison to non-doped counterparts. The P/F incorporated carbon delivers reversible capacity of 812 mAh g(-1) and 409 mAh g(-1) at 0.1 A g(-1) when tested as anode in lithium/sodium ion coin cell. The long term cycling of the material at a higher current rate of 1.0 A g(-1) is also impressive. The reason for this enhanced electrochemical performance has been analysed through electrochemical impedance spectroscopy and post mortem electron microscopic studies. The increase in interlayer spacing, cell volume and ionic conductivity in the P/F incorporated carbon which leads to an improvement in the electrochemical properties has also been corroborated via DFT analysis.