Solvothermal synthesis of graphene encapsulated selenium/carboxylated carbon nanotubes electrode for lithium–selenium battery

Lithium selenium batteries have received extensive attention for high volumetric energy density of 3254 mAh cm−3. However, the dissolution and volume change of selenium leads to rapid decay of capacity during the cycling process, which remains a challenge. Herein, we successfully synthesized the graphene encapsulated selenium/carboxylated carbon nanotubes (Se/CCNTs-RGO) composites by solvothermal strategy using 1-octadecene as the solvent. The CCNTs and RGO, which reduces volume expansion, enhances the rate of ion transport, and strongly limits the soluble polyselenides. The resulting Se/CCNTs-RGO exhibits outstanding electrochemical performances. It can deliver initial discharge capacity of 592 mAh g−1 at density of 200 mA g−1 and show excellent rate capability. This preparation method can be extended to other electrode materials for battery systems.