Component-controllable bimetallic nickel cobalt selenides (NixCo1-x)0.85Se for high performance supercapacitors

In this study, bimetallic nickel cobalt selenides (NixCo1-x)0.85Se with different Ni to Co ratios were synthesized via one-pot hydrothermal treatment, and their electrochemical performance, as electrode materials for supercapacitors, were systematically studied for the first time. The bimetallic nickel cobalt selenides (NixCo1-x)0.85Se show more excellent electrochemical performance than that of the monometallic selenides Ni0.85Se and Co0.85Se. Meanwhile, through varying the Ni to Co ratio, the (Ni0.5Co0.5)0.85Se delivers the highest specific capacity, excellent rate capability, and good cycling stability. Upon analysis, the superior electrochemical performance of bimetallic nickel cobalt selenides (NixCo1-x)0.85Se, especially (Ni0.5Co0.5)0.85Se, ascribe to the synergistic effect between the more electrochemical active composition (Ni ions) and the faster transfer of electron (Co ions).