The current challenges in the usage of liquid electrolyte in energy storage devices are closely correlated with the flexibility and portability of the devices. In this paper, a highly flexible, pouch-type hybrid supercapacitor in liquid electrolyte based on a binderless cobalt hydroxide–cobalt molybdate (CoMoO₄@Co(OH)₂) core–shell structure (prepared by electrochemical deposition; ECD) sandwiched with honeycomb-like porous carbon derived from laboratory waste tissue paper (prepared by a hydrothermal reaction and carbonization) is presented. Its excellent hierarchical core–shell structure and honeycomb-like porous carbon results in a large electrochemically active surface area, which yields a high areal capacity of 265 μA h cm⁻² and excellent specific capacitance of 227 F g⁻¹ in liquid potassium hydroxide (KOH) electrolyte with excellent cyclic stability. An assembled pouch-type hybrid supercapacitor using the prepared core–shell structure as the positive electrode and porous carbon as the negative electrode shows an extended working voltage of 1.5 V in 2 M KOH electrolyte, which stores a maximum energy density of 167.5 μW h cm⁻². Interestingly, the fabricated pouch-type supercapacitor shows an excellent flexibility under different bending conditions and exhibits remarkable cyclic stability with >98% capacitance retention even after long cycles. Furthermore, the capability of the device is demonstrated by integrating it with a solar cell to drive the various types of light-emitting diodes (LEDs) and seven segment displays for self-powered applications.

The triboelectric effect is one of the most trending effects in energy harvesting technologies, which use one of the most common effects in daily life. Herein, an impervious silicone elastomer-based triboelectric nanogenerator (SE-TENG) is reported with a micro roughness-created silicone elastomer film and Ni foam as triboelectric layers with opposite surface charges. The surface roughness modification process was performed via a cost-effective soft lithography technique using sandpaper. The replicated film was then used as the negative triboelectric layer and porous Ni foam was used as the positive triboelectric layer. The device exhibited the advantage of high stability due to the porous nature of the Ni foam, which could not damage the roughness pattern of the elastomer film. The device generated a maximum electrical output of ∼370 V/6.1 μA with a maximum area power density of ∼17 mW m⁻² at a load resistance of 1 GΩ. Furthermore, the SE-TENG device was packed using polyethylene to protect it from humidity and made to be a water-resistant SE-TENG (WR-SE-TENG). The device was stable under different percentages of relative humidity, showing a uniform electrical output in the range of 10% RH to 99% RH. This proves that the packing is highly resistant against moisture and humidity. The device was also used for demonstrating its capability in powering small electronic components such as charging commercial capacitors, glowing LEDs and powering wrist watches. Further, the WR-SE-TENG device was used to scavenge bio-mechanical energy from human motions and also used for a real-time application of zero power consuming/self-powered pressure sensors. As an active sensor, the device showed linear sensing behavior and a sensitivity of 0.492 μA kPa⁻¹.