Potato-starch-based hard carbon microspheres: Preparation and application as an anode material for sodium-ion batteries

Although developing spherical biomass hard carbon materials as an anode for sodium-ion batteries (SIBs) is important because such materials exhibit high bulk density, stable structure, and low cost, complex chemical processing and high time-consuming limit its commercial production. Herein, we develop a thermal conductive agent and controlled oxidation method to fabricate potato starch-based carbon microspheres in which natural potato starch is used as a precursor. Impressively, inert carbon nanospheres as thermal conductive agent can promote starch particles heating uniformity, thus preventing fusion during oxidation and significant shortening of the oxidation time. When used as an anode in SIBs, the optimized PC-1400 (carbonization temperature is 1400 °C) exhibits a high capacity of 303.5 mA h g−1 and a high initial coulombic efficiency of 90.6% at 0.02 A g−1. Additionally, an assembled full battery (PC-1400//NaNi0.5Mn1.5O4) delivers outstanding rate performance of >77% (10C/0.5C) at 10C, reflecting the remarkable application potential of the as-prepared anode. This study offers a new method for the controllable preparation of biomass-based microspheres for use in commercial SIBs.