An advanced novel all-solid-state asymmetric supercapacitor (ASC) device of high energy and power densities is designed on the basis of the nanoflowerlike NiSe as the positive electrode and WO 3 @PPy composite as the negative one. The porous NiSe was prepared by facile selenization of predesigned NiO nanoflowers, and the WO 3 @PPy composite was synthesized through in situ oxidative polymerization of pyrrole in the presence of dispersed WO 3 nanosticks which, in turn, was produced by a simple sulfate-assisted hydrothermal method. When tested as a supercapacitor positive electrode in the three-electrode system, the NiSe exhibits an appreciably higher specific capacitance of 1274 F g −1 at 2 A g −1 than that of the NiO nanoflower (774 F g −1 ). Again, as the negative electrode, the WO 3 @PPy composite also shows excellent electrochemical properties with a higher specific capacitance (586 F g −1 at 2 A g −1 ) than those of either of its components (WO 3 : 402 F g −1 and PPy: 224 F g −1 ). Based on these properties of the respective electrodes, a flexible ASC device was designed and fabricated by assembling the NiSe as the positive electrode with WO 3 @PPy composite as the negative electrode. The NiSe//WO 3 @PPy solid-state ASC with an extended potential window of 1.25 V demonstrates an admirable energy density of 37.3 Wh kg −1 at a power density of 1249 W kg −1 at 2 A g −1 along with outstanding long-term cycling stability that retains 91% of the initial capacitance even after 5000 charging and discharging cycles. All these results reveal the proficiency of the ASC device as a high-performance energy storage system for next-generation portable electronics.

Smart electromagnetic interference (EMI) shielding materials with tunable EMI shielding effectiveness (SE) have garnered huge attention in the fabrication of next generation EM devices as well as innovative wearable electronics. Here, we report a polydimethylsiloxane (PDMS) encapsulated soft, flexible, and stretchable polyacrylamide (PAM)-alginate (Alg)-hydrogel/silver nanorod (AgNR) composite system for EMI SE application. The PDMS encapsulation not only enhances the tensile strength of the system from ∼0.057 MPa to ∼0.724 MPa but also restricts the evaporation of water from the hydrogel matrix. Consequently, at 14.5 GHz frequency, the EMI SE (∼48.72 dB) of the hydrogel was reduced to ∼10.52 dB (72 h at 30 °C) and ∼6.44 dB (72 h at 40 °C) and ∼8.03 dB after 1 week of settlement at ambient conditions. However, for the encapsulated hydrogel, the EMI SE (∼40.65 dB) value was marginally reduced to ∼33.86 dB, ∼31.45 dB, and ∼32.42 dB, respectively, under the same conditions. Moreover, by changing the sample thickness (increasing holding pressure in a VNA sample holder), the shielding performance can be altered from ∼48.72 to ∼53.63 dB for the hydrogel and from ∼40.65 to ∼44.03 dB for the encapsulated hydrogel. Thus, these findings provide an innovative strategy to fabricate a flexible and stretchable EMI shielding material with adjustable SE by varying the content of water and applying pressure for futuristic development in smart electronics.

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Triboelectric and piezoelectric nanogenerators are explored to harvest electrical energy from the mechanical vibrations. These two effects are explored in a combined way as piezo–tribo hybrid nanogenerator (PTNG). Herein, polyvinylidene fluoride (PVDF)/ZnO nanocomposite where ZnO is synthesized is fabricated by using metal–organic framework precursors. The PTNG is fabricated by PVDF/ZnO nanocomposites coupling with the as‐fabricated poly dimethyl siloxane/reduced graphene oxide nanocomposites. The incorporation of ZnO into the polymer matrix helps to stabilize the β‐phase of the PVDF which improves the piezoelectricity. ZnO not only enhances the piezoelectricity but also influences tribolelectricity indirectly. The as‐fabricated PTNG shows the output of open‐circuit voltage ≈185 V and short‐circuit current ≈14.5 μA and power density of ≈338 μW cm−2 which can light up 40 red light‐emitting diodes (LEDs) in series connection and 22 red LEDs in parallel connection. It can also power up daily portable electronics like digital wrist watch and calculator. This PTNG, as well as, its piezoelectric part can harvest energy from various body part movements like walking, heel pressing, elbow bending, etc.