Ni dopping Co2Al ternary layered double hydroxides for improving electrochemical performance of high-performance hybrid supercapacitors

Layered double hydroxides (LDHs) is a promising electrode material for supercapacitors (SCs) because its large specific surface area and anionic tunability. Herein, an ultrathin ternary NixCo2Al layer double hydroxides nanosheet (NixCo2Al-LDHs) grown on carbon cloth (CC) substrate by hydrothermal synthesis method is reported as a high efficiency battery-type electrode in alkaline medium. The influence of Ni on the electrochemical properties and morphology of ternary metal hydroxide is first studied. By adjusting the molar concentration of nickel, we determine that Ni1Co2Al-LDHs@CC has the best electrochemical performance. The Ni1Co2Al-LDHs@CC has a high specific capacity of 1772.5 mC cm−2 at a current density of 1 mA cm−2 and it maintains outstanding capacitive retention of 93.3% after 12,000 cycles. In addition, the obtained Ni1Co2Al-LDHs@CC//AC asymmetric supercapacitors (ASC) achieves a maximum energy density of 0.102 mWh cm−2 at power density of 0.75 mW cm−2 and keep the capacitance retention of 90.98% after 12,000 cycles to successfully light LEDs (8 mm). Detailed electrochemical kinetic analysis showed that the total capacitance of Ni1Co2Al-LDHs@CC electrode come from its effective capacitive storage mechanism. It is founded that Ni has influence on the morphology and electrochemistry of ternary metal hydroxide, which provided an effective design idea and method for improving the capacitance of ternary metal hydroxide.