Novel Ultrathin Nanoflake Assembled Porous MnO<sub>2</sub>/Carbon Strip Microspheres for Superior Pseudocapacitors
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Abstract
A novel
hierarchical MnO<sub>2</sub>/carbon strip (MnO<sub>2</sub>/C) microsphere
is synthesized via galvanostatic charge–discharge of a MnO@C
matrix precursor where the carbon is from a low-cost citric acid.
This hierarchical structure is composed of manganese oxides nanoflakes
and inlaid carbon strips. The ultrathin nanoflakes assemble to form
porous microspheres with a rippled surface superstructure. Due to
its improved conductivity and remarkable increased phase contact area,
this novel structure exhibits an excellent electrochemical performance
with a specific capacitance of 485.6 F g<sup>–1</sup> at a
current density of 0.5 A g<sup>–1</sup> and an area capacitance
as high as 4.23 F cm<sup>–2</sup> at a mass loading of 8.7
mg cm<sup>–2</sup>. It also shows an excellent cycling stability
with 88.9% capacity retention after 1000 cycles. It is speculated
that the present low-cost novel hierarchical porous microspheres can
serve as a promising electrode material for pseudocapacitors