Se vacancy-rich NiMoSe@NiAl-LDH hierarchical core-shell structure towards high-performance supercapacitors

As promising electrode materials, transition metal selenides show great potential applications in energy storage devices. Here self-supported Ni0.85Se nanowires with Se vacancies (denoted as NiMoSe) on NF were synthesized by a solvothermal route and post-selenization using NiMoO4 as the precursor, which electrochemical performance was optimized by adjusting the Se feeding during the selenization. Whereas, the supercapacitive properties of the optimal NiMoSe need to be further improved for achieving higher rate capability and electrochemical stability. So, an efficient strategy was proposed to improve the electrochemical performance through welding the NiAl hydrotalcite (NiAl-LDH) nanosheets on the NiMoSe surface to construct a novel 1D-2D-3D hierarchical core-shell material (NiMoSe@LDH), which provided more active sites and ensured a high rate-capability and long-term stability. Benefiting from the synergistic effect between NiMoSe nanowires core and NiAl-LDH shell, the NiMoSe@LDH delivered a favorable specific charge of 1381.1 C g−1 at 1 A g−1 with impressive rate capability and cyclic stability (85.2% retention after 5 000 cycles at 5 A g−1). Furthermore, the as-assembled NiMoSe@LDH//AC afforded a high energy density of 50.2 Wh kg–1 at a power density of 800 W kg–1 and good cycling stability (86.5% retention at 5 A g−1 after 10 000 cycles) compared to the NiMoSe//AC (36.3 Wh kg–1 at 800 W kg–1, 77.3% retention). This work provides a new strategy for the design of high-performance transition metal selenides in next-generation energy storage devices.