Ultrahigh Energy Density Realized by a Single-Layer β-Co(OH)2 All-Solid-State Asymmetric Supercapacitor

• Published in: Angewandte Chemie International Edition Vol. 53; no. 47; pp. 12789 - 12793
• Main Authors: Gao, Shan, Sun, Yongfu, Lei, Fengcai, Liang, Liang, Liu, Jiawei, Bi, Wentuan, Pan, Bicai, Xie, Yi
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 17.11.2014; WILEY‐VCH Verlag
• Subjects: all-solid-state devices; asymmetric supercapacitors; energy materials; oriented attachment; thin films; all-solid-state devices; energy materials; asymmetric supercapacitors; oriented attachment; thin films
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.201407836

A conceptually new all‐solid‐state asymmetric supercapacitor based on atomically thin sheets is presented which offers the opportunity to optimize supercapacitor properties on an atomic level. As a prototype, β‐Co(OH)2 single layers with five‐atoms layer thickness were synthesized through an oriented‐attachment strategy. The increased density‐of‐states and 100 % exposed hydrogen atoms endow the β‐Co(OH)2 single‐layers‐based electrode with a large capacitance of 2028 F g−1. The corresponding all‐solid‐state asymmetric supercapacitor achieves a high cell voltage of 1.8 V and an exceptional energy density of 98.9 Wh kg−1 at an ultrahigh power density of 17 981 W kg−1. Also, this integrated nanodevice exhibits excellent cyclability with 93.2 % capacitance retention after 10 000 cycles, holding great promise for constructing high‐energy storage nanodevices. An atomically thin β‐Co(OH)2 sheet electrode was used to fabricate an all‐solid‐state asymmetric supercapacitor with high energy density. The β‐Co(OH)2 layers are characterized by 100 % exposed hydrogen atoms, thus facilitating efficient Faradaic redox reactions. The energy density of 98.9 Wh kg−1 can compete with the world's highest energy density for supercapacitors.