Design
of a High Performance Thin All-Solid-State Supercapacitor Mimicking
the Active Interface of Its Liquid-State Counterpart
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Abstract
Here we report an all-solid-state
supercapacitor (ASSP) which closely mimics the electrode–electrolyte
interface of its liquid-state counterpart by impregnating polyaniline
(PANI)-coated carbon paper with polyvinyl alcohol-H<sub>2</sub>SO<sub>4</sub> (PVA-H<sub>2</sub>SO<sub>4</sub>) gel/plasticized polymer
electrolyte. The well penetrated PVA-H<sub>2</sub>SO<sub>4</sub> network
along the porous carbon matrix essentially enhanced the electrode–electrolyte
interface of the resulting device with a very low equivalent series
resistance (ESR) of 1 Ω/cm<sup>2</sup> and established an interfacial
structure very similar to a liquid electrolyte. The designed interface
of the device was confirmed by cross-sectional elemental mapping and
scanning electron microscopy (SEM) images. The PANI in the device
displayed a specific capacitance of 647 F/g with an areal capacitance
of 1 F/cm<sup>2</sup> at 0.5 A/g and a capacitance retention of 62%
at 20 A/g. The above values are the highest among those reported for
any solid-state-supercapacitor. The whole device, including the electrolyte,
shows a capacitance of 12 F/g with a significantly low leakage current
of 16 μA<sup>2</sup>. Apart from this, the device showed excellent
stability for 10000 cycles with a coulombic efficiency of 100%. Energy
density of the PANI in the device is 14.3 Wh/kg