Hydrothermally assisted transformation of corn stalk wastes into high-performance hard carbon anode for sodium-ion batteries

Transforming biomass wastes such as corn stalks into electrochemical functional materials not only reduces environmental concerns associated with biomass combustion, but also provides low-cost new-energy products. Herein, a hydrothermally assisted route without using any chemicals is used to transform corn stalk wastes into high-performance hard carbon anode materials for rechargeable sodium-ion batteries, in which hydrothermal temperature is importantly optimized to eliminate the inorganic impurities and control the oxygen-containing functional group, thus finally achieving high-quality hard carbon with superior electrochemical performance. Structural properties, sodium storage performance and reaction kinetic of the resultant materials are carefully investigated by coupling X-ray diffraction, Raman spectroscopy, X-ray photon spectroscopy, and galvanostatic technique. Experimental results suggest that the optimized product prepared from hydrothermally treated corn stalk wastes delivers a high reversible capacity of 270 mAh g−1 at 0.2C, excellent high-rate capability with 172 mAh g−1 at 10C, and outstanding long-term cycling performance with capacity retention of 96.7% after 100 cycles. The result in this work indicates that hydrothermal treatment is an effective strategy to eliminate inorganic impurities from biomass wastes and promote electrochemical performance of resultant hard carbon anode for sodium-ion batteries.