期刊
ADVANCED MATERIALS
卷 29, 期 36, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.201703463
关键词
aqueous supercapacitors; phase-transformation activation; solid-solution arrays; ultrahigh voltage
类别
资金
- National Key R&D Program of China [2016YFA0202602]
- National Natural Science Foundation of China [51672205, 21673169]
- Research Start-Up Fund from Wuhan University of Technology
- Fundamental Research Funds for the Central Universities [WUT: 2016IVA083, 2017IB005]
One of the key challenges of aqueous supercapacitors is the relatively low voltage (0.8-2.0 V), which significantly limits the energy density and feasibility of practical applications of the device. Herein, this study reports a novel Ni-Mn-O solid-solution cathode to widen the supercapacitor device voltage, which can potentially suppress the oxygen evolution reaction and thus be operated stably within a quite wide potential window of 0-1.4 V (vs saturated calomel electrode) after a simple but unique phase-transformation electrochemical activation. The solid-solution structure is designed with an ordered array architecture and in situ nanocarbon modification to promote the charge/mass transfer kinetics. By paring with commercial activated carbon anode, an ultrahigh voltage asymmetric supercapacitor in neutral aqueous LiCl electrolyte is assembled (2.4 V; among the highest for single-cell supercapacitors). Moreover, by using a polyvinyl alcohol (PVA)-LiCl electrolyte, a 2.4 V hydrogel supercapacitor is further developed with an excellent Coulombic efficiency, good rate capability, and remarkable cycle life (>5000 cycles; 95.5% capacity retention). Only one cell can power the light-emitting diode indicator brightly. The resulting maximum volumetric energy density is 4.72 mWh cm(-3), which is much superior to previous thin-film manganese-oxide-based supercapacitors and even battery-supercapacitor hybrid devices.
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