Hollow Ni0.85Se/Co0.85Se/Co(OH)2 hexagonal plates for high-performance hybrid supercapacitors

Abstract

In order to improve the electrochemical performance, the combination of different battery-like electrode materials has attracted tremendous attention. Herein, a synthetic strategy has been proposed by combining Ni_0.85Se, Co_0.85Se and Co(OH)₂ materials. With nickel–cobalt hydroxide as the precursor, hollow Ni_0.85Se/Co_0.85Se/Co(OH)₂ hexagonal plates were successfully synthesized. When investigated as electrode materials for supercapacitors, outstanding electrochemical performance of the Ni_0.85Se/Co_0.85Se/Co(OH)₂ electrode is achieved by taking advantage of the high specific capacitance of Ni_0.85Se and Co_0.85Se, preferable cycling stability of Co(OH)₂ and special hollow architecture. The Ni_0.85Se/Co_0.85Se/Co(OH)₂ electrode demonstrates a high specific capacitance of 842.7 F g⁻¹ after 2000 cycles at the current density of 2 A g⁻¹ and the Ni_0.85Se/Co_0.85Se/Co(OH)₂//AC hybrid supercapacitor device shows a remarkable specific energy of 48.9 W h kg⁻¹ at a specific power of 569.4 W kg⁻¹.