title: Ultrahigh energy density realized by a single-layer β-Co(OH)2 all-solid-state asymmetric supercapacitor.
abstract: 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.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, University of Science & Technology of China, Hefei, Anhui 230026 (P.R. China).
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Sun
authors.forename: Fengcai
authors.initials: F
authors.lastname: Lei
authors.forename: Liang
authors.initials: L
authors.lastname: Liang
authors.forename: Jiawei
authors.initials: J
authors.lastname: Liu
authors.forename: Wentuan
authors.initials: W
authors.lastname: Bi
authors.forename: Bicai
authors.initials: B
authors.lastname: Pan
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
keywords: all-solid-state devices; asymmetric supercapacitors; energy materials; oriented attachment; thin films