Supercapacitor Characteristics Of Ni-Al Layered Double Hydroxides

The excessive consumption of resources,global warming,environmental pollution and other problems are increasingly serious,with the massive use of fossil energy(including coal,oil and natural gas).There is a growing demand for green,friendly,renewable and clean energy.As a new type of green energy storage devices,supercapacitors have attracted extensive attention.In this paper,the Ni-Al layered double hydroxides(Ni-Al LDHs)with different nickel-aluminum ratios were prepared by double hydrolysis method,and the optimum nickel-aluminum ratios was selected.On this basis,Ni-Al LDHs and Ni-Co-Al ternary hydroxides were prepared by dropping method.Their electrochemical properties were tested.(1)We study the effects of nickel-aluminum ratios on the performance of Ni-Al LDHs by double hydrolysis method.The Ni-Al LDHs have the best comprehensive electrochemical properties,when the nickel-aluminum ratios was Ni:Al=1:2.Its specific capacitance is 1385 F/g,and the rate capability is 87% from 0.5 A/g to 5 A/g.After1000 cycles,the specific capacitance remains 66.7%.(2)Compared with Ni-Al LDHs prepared by direct mixing method,Ni-Al LDHs prepared by dropping method has better oxidation reduction and electrochemical activity.Ni-Al LDHs prepared by dropping nickel solution into aluminum solution has the best electrochemical properties(specific capacitance of 1872 F/g,rate capability of65.3% from 0.5 A/g to 5 A/g and 83.3% retentions after 1000 cycles).(3)Ni-Co-Al ternary hydroxides with different Co contents was prepared by dropping method.Its specific capacitance is up to 2179 F/g.But the rate capability and cycle performance of Ni-Co-Al ternary hydroxide are worse than Ni-Al LDHs.