In-situ growth of hierarchical Ni-Co LDH/CoMoO4 nanosheets arrays on Ni foam for pseudocapacitors with robust cycle stability

In this work, a nanoarray electrode composed of CoMoO4 nanosheets (CoMoO4 NSs) and Co-Ni layered double hydroxide (Ni-Co LDH) nanosheets supported on Ni foam (NF) is successfully constructed by an in-situ growth route. Firstly, cobalt molybdenum arrays were fabricated by a mild hydrothermal reaction as the core. Afterwards, the as-prepared electrode was utilized as a skeleton to immobilize Ni-Co LDH with an electrochemical deposition method. The electrochemical performance of the prepared Ni-Co LDH/CoMoO4/NF electrode, compared with CoMoO4/NF electrode, illustrated a high gravimetric specific capacitance (1812 F g(-1) at 1 A g(-1)), excellent rate capability (68% at 50 A g(-1)), good cycle stability (93.7% capability retention after 5000 cycles) and the maximum energy density and power density of 62.92 Wh kg(-1) and 12.5 kW kg(-1), respectively. Moreover, an asymmetric supercapacitor (Ni-Co LDH/CoMoO4//AC) is fabricated with excellent electrochemical performance. The asymmetric supercapacitor with a maximum voltage of 1.6 V has demonstrated a high energy density of 79.28 Wh kg(-1), a high power density of 11.97 kW kg(-1) at 51.2 Wh kg(-1) and outstanding cyclic stability with the capacitance retention of 93% after 5000 cycles. The increased pseudocapacitive behaviors are related to its unique core/shell structure which provides facilitated ion diffusion, rapid electron transport kinetics, and good strain accommodation that makes it a potential choice for electrochemical energy storage owing to the their considerable electrochemical properties. (C) 2019 Elsevier B.V. All rights reserved.