Controllable synthesis of layered Co–Ni hydroxide hierarchical structures for high-performance hybrid supercapacitors

•Layered Co–Ni hydroxide hierarchical structures was successfully synthesized by a hexamethylenetetramine assisted solvothermal method.•The composition of layered CoxNi1−x hydroxide hierarchical structures was controllable adjusted with hierarchical structures maintained.•Co–Ni hydroxides with hierarchical nano-structure exhibited high performance electrochemical performance as electrode in hybrid supercapacitor.

A facile solvothermal method is developed for synthesizing layered Co–Ni hydroxide hierarchical structures by using hexamethylenetetramine (HMT) as alkaline reagent. The electrochemical measurements reveal that the specific capacitances of layered bimetallic (Co–Ni) hydroxides are generally superior to those of layered monometallic (Co, Ni) hydroxides. The as-prepared Co0.5Ni0.5 hydroxide hierarchical structures possesses the highest specific capacitance of 1767 F g−1 at a galvanic current density of 1 A g−1 and an outstanding specific capacitance retention of 87% after 1000 cycles. In comparison with the dispersed nanosheets of Co–Ni hydroxide, layered hydroxide hierarchical structures show much superior electrochemical performance. This study provides a promising method to construct hierarchical structures with controllable transition-metal compositions for enhancing the electrochemical performance in hybrid supercapacitors.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide