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A Hierarchical Interconnected Nanosheet Structure of Porous δ‑MnO2 on Graphite Paper as Cathode with a Broad Potential Window for NaNO3 Aqueous Electrolyte Supercapacitors
journal contribution
posted on 2020-03-05, 16:59 authored by Jun Wang, Ling Tian, Wenlu Xie, Xiao Wang, Xiao Long, Kai Sun, Adil Emin, Dequan Liu, Yujun Fu, Qiang Chen, Junshuai Li, Yali Li, Deyan HeThe
potential window for aqueous supercapacitor cathodes greatly
depends on the electrochemical stability of water, and thus is generally
limited to ∼1.2 V. Herein, a 1.4 V potential window (vs Ag/AgCl)
in the 5 M NaNO3 aqueous electrolyte for porous δ-MnO2 with a hierarchical interconnected nanosheet structure grown
on electrochemically roughened graphite paper by electrodeposition
is reported. A specific capacitance of ∼407.6 F g–1 is delivered at 1 A g–1, and capacitance retention
up to ∼90.7% is achieved after 5000 cycles at 8 A g–1. The aqueous asymmetric supercapacitors of 2.4 V are assembled with
the configuration of δ-MnO2//activated carbon, and
an energy density (E) of ∼38.4 Wh kg–1 is obtained at 599.7 W kg–1 (even at 12 kW kg–1, E of ∼21.7 Wh kg–1 is still delivered). Moreover, the asymmetric supercapacitors exhibit
good rate and cycling performance. Thanks to the simple preparation
for the electrode materials/structures and high device performance,
it is believed that this work provides valuable contributions to developing
aqueous supercapacitors delivering a broad working voltage window
and thus an elevated energy density.