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 the kinetic process through the modification of the 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 the spatial structure of the resultant hard carbon, and the introduction of microwaves can accelerate the 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 the elevation of the C=O ratio at the surface of the material. This approach offers a promising avenue for the modulation of biomass precursors, paving the way for the development of high-performance materials.