MXene-Derived Defect-Rich TiO2@rGO as High-Rate Anodes for Full Na Ion Batteries and Capacitors
Yongzheng Fang, Yingying Zhang, Chenxu Miao, Kai Zhu, Yong Chen, Fei Du, Jinling Yin, Ke Ye, Kui Cheng, Jun Yan, Guiling Wang, Dianxue Cao
Abstract
Abstract Sodium ion batteries and capacitors have demonstrated their potential applications for next-generation low-cost energy storage devices. These devices's rate ability is determined by the fast sodium ion storage behavior in electrode materials. Herein, a defective TiO 2 @reduced graphene oxide (M-TiO 2 @rGO) self-supporting foam electrode is constructed via a facile MXene decomposition and graphene oxide self-assembling process. The employment of the MXene parent phase exhibits distinctive advantages, enabling defect engineering, nanoengineering, and fluorine-doped metal oxides. As a result, the M-TiO 2 @rGO electrode shows a pseudocapacitance-dominated hybrid sodium storage mechanism. The pseudocapacitance-dominated process leads to high capacity, remarkable rate ability, and superior cycling performance. Significantly, an M-TiO 2 @rGO//Na 3 V 2 (PO 4 ) 3 sodium full cell and an M-TiO 2 @rGO//HPAC sodium ion capacitor are fabricated to demonstrate the promising application of M-TiO 2 @rGO. The sodium ion battery presents a capacity of 177.1 mAh g −1 at 500 mA g −1 and capacity retention of 74% after 200 cycles. The sodium ion capacitor delivers a maximum energy density of 101.2 Wh kg −1 and a maximum power density of 10,103.7 W kg −1 . At 1.0 A g −1 , it displays an energy retention of 84.7% after 10,000 cycles.