Enhanced storage performance of a low-cost hard carbon derived from biomass

Hard Carbon is the most widely used negative electrode material for sodium-ion batteries today. Achieving high storage capacity and increasing the plateau capacity, as opposed to the sloping profile, are crucial for enhancing energy density of the full cells. While several publications address the synthesis of hard carbon, the economic viability for commercial scale-up hinges on the choice of precursors. In this study, we report the electrochemical properties of hard carbon derived from two biomass precursors, sugarcane waste (bagasse) and corn waste, and compare their performances with commercially available hard carbon. The hard carbon derived from bagasse delivers a capacity of 307 mAh/g at C/10 rate and retains approximately 234 mAh/g at 3C discharge rate. We integrate surface area, pore size distribution, Raman spectroscopy, small-angle X-ray and neutron scattering data to elucidate the sodium storage mechanism in these hard carbon samples. Correlated graphitic domains with hexagonal ordering along with fractal like agglomeration of the nanosheets are quantified. The high plateau capacity of the bagasse-derived hard carbon is attributed to the characteristic morphology and size distribution of the nanosheets and their nature of agglomeration.