Molecular-level precursor regulation strategy aids fast-charging hard carbon anodes for sodium-ion batteries

Abstract

Hard carbon is commonly used as an anode material of sodium-ion batteries (SIBs), but the slow kinetic process limit its commercial scale, so the enhancement of kinetic process through modification of structure is the key to achieve a high-performance anode. Here, microwave-assisted synergistic acid treatment, targeting regulation for the content of each component in the natural lotus peduncle to change spatial structure of the resultant hard carbon, and the introduction of microwaves can accelerate reaction process, highly efficient decomposition of hemicellulose and lignin. The optimal lotus peduncle-derived hard carbon with excellent rate capability and cycling stability was obtained, possessing a high capacity of 354.8 mAh g⁻¹ at 20 mA g⁻¹ compared to the untreated material. Even at 5 A g⁻¹, it still exhibits 213.3 mAh g⁻¹ and displays a capacity retention of 90.2 % after more than 2000 cycles at 1 A g⁻¹. This noteworthy outcome can be attributed to the synthesis of the thinner and organic-inorganic hybridized SEI layer, achieved through elevation of the CO ratio at the surface of the material. This approach offers a promising avenue for the modulation of biomass precursors, paving a way for development of high-performance materials.