Co_xNi_(1-x) double hydroxide nanoparticles with ultrahigh specific capacitances as supercapacitor electrode materials

摘要

Cobalt nickel double hydroxides (Co_xNi_(1-x) LDHs) nanoparticles were synthesized by a polyvinyl pyrrolidone-assisted chemical co-precipitation method. It was found that the ratio between Co and Ni had a significant effect on their electrochemical activities. The specific capacitance of 2614 F g~(-1) was achieved when the atomic ratio of Co to Ni was equal to 0.57:0.43. This Co_(0.57)Ni_(0.43) LDH sample had a BET specific surface area of 109.8 m~2 g~(-1) and total pore volume of 0.6036 cm~3 g~(-1), and its pore size distribution was mainly in the range of 1.5-5 nm, which led to the high liquid-solid interfacial area and further increased the utilization of the active materials. Additionally, the Co_(0.57)Ni_(0.43) LDH electrode exhibited a good electrochemical stability with 86.4% of the initial capacitance over 1000 consecutive cycles at 5 A g~(-1).