Porous Ti2Nb10O29−x Microspheres Wrapped by Holey-Reduced Graphene Oxide as Superior Anode Material for High-rate Performance Lithium-ion Storage

Ti 2 Nb 1 0 O 2 9 (TNO) is considered as a potential anode material due to its high capacity/power density and reliable safety. However, its poor electronic conductivity restricts its rate performance, which is important for its application in electric vehicles (EVs). In this study, we fabricated a hybrid of Ti 2 Nb 1 0 O 2 9 − x /holey-reduced graphene oxide (TNO x /HRGO) by a two-step method. In the structure of TNO x /HRGO, TNO x microspheres with oxygen vacancies are wrapped by gossamer-like HRGO. The oxygen vacancies of TNO x and the high conductivity of HRGO can effectively enhance the electronic conductivity of the TNO x /HRGO hybrid, and the HRGO holes are beneficial for the transmission of lithium-ion ( Li + ). The synergy effect of above features improves the rate performance of the TNO x /HRGO hybrid. In addition, the existence of HRGO can buffer volume expansion during the insertion processes of Li + , which can improve cyclic stability of the TNO x /HRGO hybrid. Consequently, the TNO x /HRGO electrode has excellent lithium-ion storage capacity, with high-rate performance (242 mAh/g at 10 ∘ C, 225 mAh/g at 20 ∘ C and 173 mAh/g at 40 ∘ C) and excellent cyclic stability (98.0% capacity retention after 300 cycles at 10 ∘ C). This work reveals that TNO x /HRGO can be a potential anode material for high-rate-performance lithium-ion storage.