CoNi2S4 Nanoparticle/Carbon Nanotube Sponge Cathode with Ultrahigh Capacitance for Highly Compressible Asymmetric Supercapacitor

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2018-07, Vol.14 (27), p.n/a
• Main Authors: Cao, Xin, He, Jin, Li, Huan, Kang, Liping, He, Xuexia, Sun, Jie, Jiang, Ruibing, Xu, Hua, Lei, Zhibin, Liu, Zong‐Huai
• Format: Article
• Language: English
• Subjects: asymmetric supercapacitors; Capacitance; Carbon nanotubes; Cathodes; CNT sponges; Compressibility; compressible; CoNi2S4; Deformation mechanisms; electrodepositing; Electrodes; Energy storage; Flux density; Nanoparticles; Nanotechnology; Nanotubes; Supercapacitors
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201800998

Compared with other flexible energy‐storage devices, the design and construction of the compressible energy‐storage devices face more difficulty because they must accommodate large strain and shape deformations. In the present work, CoNi2S4 nanoparticles/3D porous carbon nanotube (CNT) sponge cathode with highly compressible property and excellent capacitance is prepared by electrodepositing CoNi2S4 on CNT sponge, in which CoNi2S4 nanoparticles with size among 10–15 nm are uniformly anchored on CNT, causing the cathode to show a high compression property and gives high specific capacitance of 1530 F g−1. Meanwhile, Fe2O3/CNT sponge anode with specific capacitance of 460 F g−1 in a prolonged voltage window is also prepared by electrodepositing Fe2O3 nanosheets on CNT sponge. An asymmetric supercapacitor (CoNi2S4/CNT//Fe2O3/CNT) is assembled by using CoNi2S4/CNT sponge as positive electrode and Fe2O3/CNT sponge as negative electrode in 2 m KOH solution. It exhibits excellent energy density of up to 50 Wh kg−1 at a power density of 847 W kg−1 and excellent cycling stability at high compression. Even at a strain of 85%, about 75% of the initial capacitance is retained after 10 000 consecutive cycles. The CoNi2S4/CNT//Fe2O3/CNT device is a promising candidate for flexible energy devices due to its excellent compressibility and high energy density. The asymmetric supercapacitor (CoNi2S4/carbon nanotube (CNT)//Fe2O3/CNT) is assembled by using CoNi2S4/CNT sponge as positive electrode and Fe2O3/CNT sponge as negative electrode in 2 m KOH solution. The assembled device exhibits not only excellent energy density of up to 50 Wh kg−1 at a power density of 847 W kg−1, but also shows the structural stability with nearly full recovery from 80% strain.