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Transition metal boride (TMB) is considered as a promising battery-type material of supercapacitors (SCs), owing to abundant electrochemically active sites, strong electrical conductivity , high chemical and thermal stability, and high theoretical capacity. However, serious aggregations of TMB substantially reduces structural stability and electrochemical performance. A conductive support is required to improve TMB dispersion and promote energy storage ability. In this study, a basic wet chemical reduction method is utilized to synthesize cobalt boride (CoB), nickel boride (NiB), and nickel cobalt boride (NiCoB) as battery-type materials of SCs. The NiCoB presents superior electrochemical results due to the highest theoretical capacity and abundant redox states of Ni and Co. Two-dimensional titanium carbide (MXene) is further incorporated in NiCoB (NiCoB/MXene), which demonstrates a significant specific capacity of 1240 C g −1 at 1 A g −1 and an outstanding rate capability of 73.9% (916 C g −1 at 40 A g −1 ), attributing to higher conductivity, enhanced dispersion of NiCoB on MXene , and synergistic effects from capacitive MXene and redox active NiCoB. A hybrid SC assembled by NiCoB/MXene and activated carbon electrodes delivers a maximum energy density of 80.5 W h kg −1 at 850 W kg −1 , and maintains a high capacitance retention of 83.4% over 20,000 cycles.
Chen et al. (Mon,) studied this question.