Construction of hierarchical NiMnSe/NiCo-OH with enhanced electrochemical property for high energy density supercapacitors

As attractive electrode materials, transition-metal selenides (TMSes) possess high theoretical capacity and abundant valence states for supercapacitors. Nevertheless, applications of TMSes are restricted due to volume changes and self-agglomeration in electrochemical processes. Constructing heterostructures with suitable electrode materials is a promising strategy to address the limitations. Herein, a 3D hierarchical NiMnSe/NiCo-OH heterostructure was synthesized by decorating NiCo-OH on the NiMnSe surface via hydrothermal method. The multicomponent and 3D hierarchical heterostructure not only provided abundant active sites along with richly accessible charge transport channels, but also increased structural stability. Benefiting from the multi-metal active sites and unique heterostructure, the designed NiMnSe/NiCo-OH exhibited an excellent electrochemical property, which gave a high specific charge of 1634.6 C g⁻¹ at 1 A g⁻¹ and good cycling stability (89.7 % retention at 5 A g⁻¹ after 5 000 cycles). At the same time, the assembled NiMnSe/NiCo-OH//activated carbon hybrid supercapacitor demonstrated a satisfactory performance, achieving a long cycle life and energy density of 69.2 Wh kg⁻¹ at 800 W kg⁻¹, which shed light on the potential in electrochemical energy-storage.