Here, we report a novel synthetic strategy to prepare a highly conducting polyethylenedioxythiphene (PEDOT) phase on flexible cellulose paper formed by inducing surfactant-free interfacial polymerization at the interface of two immiscible liquids. The illustrated process is highly scalable in such a way that very large flexible PEDOT paper can be prepared in 2-3 h under laboratory conditions. The obtained PEDOT-paper possesses efficiently packed π-conjugated chains and increased doping level which is proven by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and conductivity and UV-visble measurements. This favourable change has been attained by the slow polymerization coupled with the high dielectric constant of the interface, which stabilise the counter ions through hydrogen bonding. This helps for better inter-chain and intra-chain charge mobility, leading to conductivity as high as 375 S cm -1 compared to 30 S cm -1 of the PEDOT prepared in n-butanol. A low sheet resistance of 3 Ω/□ is achieved by multiple coating, which is found to be stable even after two months under ambient conditions and at various flexible and bending conditions. A flexible solid-state supercapacitor with an overall thickness of 0.17 mm made from the PEDOT paper and PVA-H 2 SO 4 as the solid electrolyte exhibits a volumetric energy density of 1 mWh cm -3 . The specific capacitance measured per mass of PEDOT in the system is 115 F g -1 along with a high volumetric capacitance of 145 F cm -3 . The above observed values are significantly higher compared to the bulk PEDOT tested on solid current collectors as well as highest among the literature reports. The flexible devices are found to be very stable during the charge-discharge cycling under twisted and bending conditions for more than 3800 cycles. A 3.6 V inter-digitized flexible device could also be made in a single PEDOT paper, which is found to be powered enough to glow an LED under flexible conditions.

Poor mechanical stability of the polymer electrolyte membranes remains one of the bottlenecks towards improving the performance of the proton exchange membrane (PEM) fuel cells. The present work proposes a unique way to utilize crystalline covalent organic frameworks (COFs) as a self-standing, highly flexible membrane to further boost the mechanical stability of the material without compromising its innate structural characteristics. The as-synthesized p-toluene sulfonic acid loaded COF membranes (COFMs) show the highest proton conductivity (as high as 7.8×10 S cm ) amongst all crystalline porous organic polymeric materials reported to date, and were tested under real PEM operating conditions to ascertain their practical utilization as proton exchange membranes. Attainment of 24 mW cm power density, which is the highest among COFs and MOFs, highlights the possibility of using a COF membrane over the other state-of-the-art crystalline porous polymeric materials reported to date.

We report the design of an all-solid-state supercapacitor, which has charge storage characteristics closely matching that of its liquid-state counterpart even under extreme temperature and humidity conditions. The prototype is made by electro-depositing polyethylenedioxythiophene (PEDOT) onto the individual carbon fibers of a porous carbon substrate followed by intercalating the matrix with polyvinyl alcohol-sulphuric acid (PVA-H2SO4) gel electrolyte. The electrodeposited layer of PEDOT maintained a flower-like growth pattern along the threads of each carbon fiber. This morphology and the alignment of PEDOT led to an enhanced surface area and electrical conductivity, and the pores in the system enabled effective intercalation of the polymer-gel electrolyte. Thus, the established electrode-electrolyte interface nearly mimics that of its counterpart based on the liquid electrolyte. Consequently, the solid device attained very low internal resistance (1.1 Ω cm(-2)) and a high specific capacitance (181 F g(-1)) for PEDOT at a discharge current density of 0.5 A g(-1). Even with a high areal capacitance of 836 mF cm(-2) and volumetric capacitance of 28 F cm(-3), the solid device retained a mass-specific capacitance of 111 F g(-1) for PEDOT. This is in close agreement with the value displayed by the corresponding liquid-state system (112 F g(-1)), which was fabricated by replacing the gel electrolyte with 0.5 M H2SO4. The device also showed excellent charge-discharge stability for 12 000 cycles at 5 A g(-1). The performance of the device was consistent even under wide-ranging humidity (30-80%) and temperature (-10 to 80 °C) conditions. Finally, a device fabricated by increasing the electrode area four times was used to light an LED, which validated the scalability of the process.

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-H2SO4 (PVA-H2SO4) gel/plasticized polymer electrolyte. The well penetrated PVA-H2SO4 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(2) 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(2) 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(2). 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.