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

Ti2Nb10O29(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 Ti2Nb10O29-x/holey-reduced graphene oxide (TNOx/HRGO) by a two-step method. In the structure of TNOx/HRGO, TNOx microspheres with oxygen vacancies are wrapped by gossamer-like HRGO. The oxygen vacancies of TNOx and the high conductivity of HRGO can effectively enhance the electronic conductivity of the TNOx/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 TNOx/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 TNOx/HRGO hybrid. Consequently, the TNOx/HRGO electrode has excellent lithium-ion storage capacity, with high-rate performance (242 mAh/g at 10 degrees C, 225 mAh/g at 20 degrees C and 173 mAh/g at 40 degrees C) and excellent cyclic stability (98.0% capacity retention after 300 cycles at 10 degrees C). This work reveals that TNOx/HRGO can be a potential anode material for high-rate-performance lithium-ion storage.