Fabricated Ga (III) heterovalent substituted NiCo layered double hydroxides (NiCoGa-LDHs) electrode material for designed hybrid supercapacitor

Abstract

Ternary metal layered double hydroxides (LDHs) have been widely used in supercapacitors (SCs) due to their polyvalent state and high electrochemical activity. In this study, Ga (III) doped NiCo layered double hydroxides (NiCoGa-LDHs) electrode material is prepared on carbon cloth (CC) by simple one-step hydrothermal method for the first time. The effects of Ga3+ with different molar ratios on the structure, morphology, crystallinity, ion transport mechanics and electrochemical properties of ternary LDHs electrode materials are systematically investigated. At Ga3+ = 1.0, the as-synthesized Ni1Co3Ga1-LDHs@CC exhibits a special electrochemical capacitance of 2012.5 F g-1 at 1 A g-1 with 57.7% capacitance retention observed at 5.0 A g-1. The synthesis and evaluation of the two bimetallic NiCo-LDHs and NiGa-LDHs are similar in order to demonstrate the performance improvement of gallium heterovalent substitution. And heterovalent substitution of gallium for cobalt ion and nickel ion is proved indirectly. An Asymmetric supercapacitors (ASCs) device is assembled with Ni1Co3Ga1-LDHs@CC as anode and mesoporous carbon (MPC) as cathode, providing a high energy density of 84.22 Wh kg-1 at a power density of 800.1 W kg-1, with excellent cyclic stability. This study provides a new way to improve the electrochemical performance and stability of ternary metal LDHs.