Boosting sodium ion storage by anchoring MoO2 on vertical graphene arrays

Abstract

Developing high-capacity anodes is of great importance for the advancement of sodium ion batteries. In this work, we report a powerful combined method of plasma enhanced chemical vapor deposition–electrodeposition (PECVD–ED) to construct high-quality vertical graphene/MoO₂ (VG/MoO₂) core/shell arrays. The conductive MoO₂ (n-type semiconductor) shell is uniformly electrodeposited on the VG core to form a binder-free integrated electrode. Compared with carbon fibre cloth-supported MoO₂ film (CFC/MoO₂), the obtained VG/MoO₂ core/shell arrays display a higher surface area, better mechanical stability and improved electrical conductivity. Due to these positive advantages, the VG/MoO₂ arrays show enhanced sodium ion storage performance with a reversible capacity of 678 mA h g⁻¹ (vs. 542 mA h g⁻¹ for CFC/MoO₂) at the current density of 100 mA g⁻¹, and a stable cycling life with a capacity retention of 81.7% (vs. 62.1% for CFC/MoO₂) after 500 cycles. Our results provide a new route for the synthesis of high-capacity anodes for sodium ion batteries.