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Ni­(OH)2 has low production cost and high theoretical specific capacity, while on account of the poor electronic conductivity, it shows inferior electrochemical performance including cycling stability and rate capability. This work focuses on a composite material that is in situ grown Ni­(OH)2 nanosheets on reduced graphene oxide (rGO), and employing the fewer-defect rGO to build a three-dimensional conductive network provides outstanding conductivity. The specific capacitances (C m) of the Ni­(OH)2/rGO (NHG) electrode are 2776 F·g–1 at 2 A·g–1 and even 1570 F·g–1 at 50 A·g–1, demonstrating remarkable rate capability. It indicates that the combination of the nano grown Ni­(OH)2 and rGO conductive substrate shortens the ion diffusion path and increases the electron transfer rate; hence, the composite rate capability has been significantly improved. The composite materials and active carbon were combined to be an asymmetric supercapacitor, which had a high energy density of 39.24 Wh·kg–1 at 1962 W·kg–1. After 10,000 cycles at 5 A·g–1, the capacity retains 91.4%.

Bronze phase TiO2 [TiO2(B)] has great research potential for sodium storage since it has a higher theoretical capacity and ion mobility compared with other phases of TiO2. In this case, preparing porous TiO2(B) nanosheets, which can provide abundant sodium insertion channels, is the most effective way to improve transport kinetics. Here, we use the strong one‐dimensional TiO2 nanowires as the matrix for stringing these nanosheets together through a simple solvothermal method to build a bunchy hierarchical structure [TiO2(B)‐BH], which has fast pseudocapacitance behavior, high structural stability, and effective ion/electron transport. With the superiorities of this structure design, TiO2(B)‐BH has a higher capacity (131 vs. 70 mAh g−1 [TiO2‐NWs] at 0.5 C). And it is worth mentioning that the reversible capacity of up to 500 cycles can still be maintained at 85 mAh g−1 at a high rate of 10 C. Meanwhile, we also further analyzed the sodium storage mechanism through the ex‐situ X‐ray powder diffraction test, which proved the high structural stability of TiO2(B)‐BH in the process of sodiumization/de‐sodiumization. This strategy of uniformly integrating nanosheets into a matrix can also be extended to preparing electrode material structures of other energy devices.

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