MXene-Derived Defect-Rich TiO(2)@rGO as High-Rate Anodes for Full Na Ion Batteries and Capacitors

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. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-020-00471-9) contains supplementary material, which is available to authorized users.