Hard carbon with opened pore structure for enhanced sodium storage performance

Abstract

Pore structure of hard carbon plays a great role impact on its Na+ storage capacity. Here, a waste wood derived hard carbon with opened pores (OP-HC) has been fabricated with polyvinyl pyrrolidone (PVP) as additive. Ex-situ SAXS and HR-TEM testing results indicate that OP-HC with opened pores and enlarged d002 interlayer spacing facilitate the reversible (de)sodiation of Na+ ions. In-situ TEM and XRD testing results demonstrate that OP-HC shows an excellent structure stability during the (de)sodiation process. Thus, OP-HC delivers a high reversible charge capacity is 350.7 mAh g−1 at 0.05 C and ultra-high initial Coulombic efficiency (ICE) of 94.9%. Moreover, OP-HC exhibits an excellent cycling stability, and the assembled 18650 full cell with OP-HC anode can achieve a high capacity retention of 94.5% after 400 cycles at 1.0 A. The excellent electrochemical performance and deep insights into OP-HC with opened pores and increased d002 interlayer spacing offers a new strategy to design high performance HC anode for SIBs.