Insights into sodium-ion batteries through plateau and slope regions in cyclic voltammetry by tailoring bacterial cellulose precursors

Abstract

Hard carbon with high capacity with fast sodium storage is the most promising anode material for sodium-ion batteries. Many works have been made on improving the plateau and slope capacity of hard carbon in order to obtain high energy-power density sodium-ion batteries. This work explores sodium ions storage behaviors in porous carbon materials from the perspective of plateau and slope regions in cyclic voltammetry through tailoring the bacterial cellulose precursor with sulfuric acid and two-step carbonization. The influences of structure parameters including carbon layer distance, oxygen content, graphitization degree, and length and thickness of graphite crystallite help understand the strategies for improving the plateau and slope capacity. The results indicate the pre-carbonization of bacterial cellulose precursors via H2SO4 treatment introduces oxygen groups in both of bacterial cellulose matrix and bacterial cellulose derived carbon, which is beneficial for improving the slope and plateau capacity. The obtained bacterial cellulose-based carbon material with rational closed pores and micro-mesoporous structure shows a good discharging capacity of 420.6 mA h g−1 at 0.03 A g−1, and the enhanced plateau-slope capacity is 255.2 -167.1 mA h g−1 at 0.03 A g−1, respectively.