Flexible Solid-State Asymmetric Supercapacitor with High Energy Density and Ultralong Lifetime Based on Hierarchical 3D Electrode Design
Yuchen Qian, Jingjing Zhang, Junhong Jin, Shenglin Yang, Guang Li
Abstract
Hierarchical structure design of transition metal compounds is a promising method for improving the electrochemical properties of supercapacitors. In this work, a 3D electrode is obtained by in situ growing of NiMoO4@NiCo2O4 core–shell nanorods on Ni foam (NF) followed by an annealing process (NF@NiMoO4@NiCo2O4). The hierarchical structure with ordered pores on a surface enables a uniform charge distribution, provides effective electron/ion transfer channels, and maintains structural integrity over long periods of cycling, which collectively results in excellent electrochemical properties with an extraordinary specific capacitance of 1920 F g–1 at 1 A g–1 as well as 91.6% capacitance retention after 10 000 cycles. Furthermore, a flexible solid-state asymmetric supercapacitor fabricated with NF@NiMoO4@NiCo2O4 achieves a superior energy density of 54.5 Wh kg–1 (at 845 W kg–1) and an outstanding cycling stability with 83% capacity retention over 10 000 cycles. The hierarchical 3D electrode design in this work will contribute to the development of high-performance supercapacitors and shows promising prospects in flexible and portable energy storage systems.