Bark-Derived Oxygen-Doped Porous Hard Carbon Anodes for Potassium-Ion Batteries

Oxygen content and specific surface area are key factors affecting the electrochemical performance of biomass-derived hard carbon anodes for potassium-ion batteries (PIBs). Increasing oxygen content enhances potassium storage, improving cycle stability and rate performance. Furthermore, optimizing porous structures boosts specific surface area, facilitating potassium ion diffusion and increasing capacity. Herein, a cost-effective and environmentally friendly strategy is proposed, using bark as a precursor, oxygen as the oxidant, and pluronic P123 as the template agent. Oxygen-doped porous hard carbon anodes are synthesized via pre-oxidation and hydrothermal processing. These anodes exhibit large interlayer spacing, high specific surface area, and significant oxygen content, resulting in excellent electrochemical stability and capacity. The anodes maintain a high specific discharge capacity of 230.2 mAh g⁻¹ after 200 cycles at 0.1 A g⁻¹, with minimal capacity loss. After 3000 cycles at 1 A g⁻¹, the capacity retention is 80%. This work demonstrates an effective method for utilizing bark to produce high-performance hard carbon anodes for PIBs, advancing the development of bark-derived materials for energy storage.