Engineering time-dependent MOF-based nickel boride 2D nanoarchitectures as a positive electrode for energy storage applications

[Display omitted] •Simple boronization kinetics with room temperature proved the formation of Ni-ZIF.•Ni-ZIF/Ni-B-24 h electrode demonstrated the high capacity of 260C g−1 at 10 A/g.•Fabricated device attains 46.6 Wh kg−1 energy density at 1600 W kg−1 power density.•A long-term stability shows 99.2 % Coulombic efficiency over 5000 cycles. It is of great importance to design rationally combined metal-organic frameworks (MOFs) with multifunctional nano geometries to develop advanced energy storage devices. We devised a simple room-temperature boronization system to produce ultrathin Ni-ZIF/Ni-B nanosheets with plenty of crystalline-amorphous phase barriers. The Ni-ZIF/Ni-B-24 h nanoflakes electrodes exhibited a specific capacitance of 104.2F g−1 with the cyclic stability of 94.5 % using the flaky architecture and inherent properties of the Ni-ZIF/Ni-B-24 h nanoflakes. Furthermore, an asymmetric supercapacitor made of Ni-ZIF/Ni-B-24 h and activated carbon had a high specific capacitance of 370.7F g−1 at 1 A/g, and the energy density of 131.8 W h kg−1 at a power density of 800 W kg−1. Intriguingly, Ni-ZIF/Ni-B-24 h nanoflakes have consistently delivered higher specific capacities because of the adequate electrochemical active sites and an increase in electron transfer rate during redox reactions.