Polymer Blends for Energy Storage Devices: A Review

ABSTRACT The growing need for effective, flexible, and sustainable energy storage systems has driven increasing attention toward tunable electrochemical, mechanical, and dielectric properties in varied polymer‐blend architectures. The following review consolidates recent developments in the field of conducting polymer blends, naturally occurring biopolymer matrices, and synthetic PVDF, PVA, and PEO systems, focusing on the fundamental structure–property framework guiding ion transport, charge storage, and longevity. Important underlying mechanisms that include segmental relaxation, interfacial polarization, dipolar alignment, and polymer‐salt coordination will be discussed with respect to the degree of blend miscibility, crystalline‐amorphous balance, and microstructural control. Attention is paid to the development of various methodologies to enhance ionic mobility, establish stable charge‐transport pathways, and promote dielectric performance by the incorporation of nanofillers, plasticization, functional doping, hydrogen‐bond engineering, and crystallinity suppression. Consolidation of these findings in supercapacitors, lithium‐ and proton‐conducting batteries, high‐frequency capacitors, flexible electronics, and solar‐energy harvesting devices points to polymer‐blend engineering as a scalable and versatile strategy for next‐generation solid‐state and multifunctional energy storage devices. Finally, the review covers emerging trends and design principles in order to direct the future design of sustainable, high‐performance polymer‐blend materials.