Self-supported electrode constructed by hierarchical nickel-cobalt selenide nanosheet arrays for high-performance flexible supercapacitors
Qu Liu, Yinxuan Ding, Long Zhang, Yunbiao Li, Chaoyan Jiang, Lingli Cheng, Zhen Li, Zhen Li
Abstract
Flexible supercapacitors are a promising candidate as the energy storage device for wearable and portable electronics. Herein, nickel-cobalt selenide ((Ni,Co)Se 2 ) nanosheet arrays with the hierarchical nanoparticle/nanosheet structure grown in-situ on acidified carbon cloth (CC) flexible substrate are prepared through simple hydrothermal and selenization process. The hierarchical (Ni,Co)Se 2 nanosheet arrays with rough and porous surface enlarge the contact area between the electrode and electrolyte, and provide more abundant electrochemical active sites. While CC improves electrical conductivity , and renders a binder-free and flexible substrate with nanosheet arrays vertically anchored well on without aggregation. Consequently, the self-supported (Ni,Co)Se 2 /CC electrode displays an ultrahigh specific capacitance of 2054 F g −1 (285 mA h g −1 ) at 1 A g −1 and remarkable rate performance of 90.3 % retention at 10 A g −1 . The all-solid-state flexible supercapacitor is assembled with (Ni,Co)Se 2 /CC as the positive electrode and activated carbon (AC/CC) as the negative electrode. The device exhibits a high energy density of 44.6 W h kg −1 at a power density of 976 W kg −1 , as well as excellent cycling performance with 85.2 % capacitance retention after 5000 cycles and mechanical flexibility. The high-performance of (Ni,Co)Se 2 /CC self-supported electrode has a promising application in flexible energy storage devices.