Fabrication of CoMo-layered double hydroxide@Co2MoO4 nanosheets for enhancing the performance of asymmetric capacitors

As a new class of energy storage devices, supercapacitors (SCs) exhibit performance that falls between batteries and traditional capacitors. Ternary transition metal oxide CoMoO4 materials possess abundant redox active sites, but their conductivity and cycle stability are unsatisfactory when utilized as electrodes for supercapacitors. Here, a nanostructured CoMo-layered double hydroxide (CoMo-LDH)@ Co2MoO4 nanosheets is directly grown on nickel foam (NF) using a two-step hydrothermal method. The CoMo-LDH@Co2MoO4 composite electrode exhibits a relatively high areal capacitance of 3672 mF cm−2 at 2 mA cm−2 and still retains 88.3% capacity at 20 mA cm−2. Furthermore, CoMo-LDH@Co2MoO4 is utilized as the positive electrode to construct an asymmetric solid-state supercapacitors (ASC). The results proved that the CoMo-LDHs and Co2MoO4 nanosheets offer a higher capacity because of the reversible redox reactions involving the movement of OH− ions during both charging and discharging processes.