Nickel–Cobalt-Layered Double Hydroxide Nanosheets Supported on NiMoO₄ Nanorods with Enhanced Stability for Asymmetric Supercapacitors

Nickel molybdate (NiMoO4) is a typical pseudocapacitance material with high specific capacity. However, its inherent shortcomings of poor electrical conductivity and unstable structure caused by hindered migration of electrons and local aggregation of charges/ions seriously affect its energy-storage performance. Herein, using NiMoO4 nanorods as the nucleation matrix, a hydrothermal approach was used to fabricate NiMoO4/NiCo-layered double hydroxide (LDH) nanocomposites. The NiCo-LDH nanosheets uniformly grown on NiMoO4 nanorods not only provided a facile electron transfer channel and abundant redox active sites but also its interwoven nanosheet shell can retard the volume change and result in irreversible dissolution of the NiMoO4 core during the charge/discharge process. Therefore, the NiMoO4/NiCo-LDH nanocomposite possesses a high specific capacity (153.7 mAh g–1 at 1 A g–1) and enhanced cyclic stability. Furthermore, the NiMoO4/NiCo-LDH nanocomposite is utilized as a positive electrode of an asymmetric supercapacitor (ASC). The NiMoO4/NiCo-LDH//activated horsetall tree-based carbon (AHTC) ASC achieves a high energy density of 40.3 Wh kg–1 at 425.5 W kg–1, as well as excellent cycle performance. The synergistic effect of nanocomposites between the various metal compounds with integrated architectures provides unique insights into the development of nanocomposites for energy-storage devices.