The Role of Phase‐Transition and Electrically Active Polymers in Energy Storage and Harvesting Applications: A Review

ABSTRACT The growing demand for sustainable and efficient energy technologies has catalyzed significant interest in polymer‐based materials for energy storage and energy harvesting applications. Polymers with tunable electrical properties and phase transition behavior offer a unique combination of flexibility, light weight, and processability, making them ideal candidates for use in advanced batteries, supercapacitors, solar cells, piezoelectric devices, and phase change materials. This review provides a comprehensive overview of the roles that conductive, dielectric, piezoelectric, and thermally responsive polymers play in improving the performance of energy systems. It emphasizes recent progress in polymer chemistry, nanostructuring techniques, and hybrid material design, showcasing how these innovations contribute to enhanced energy density, mechanical stability, and multifunctionality. The review also explores the integration of biodegradable and bio‐based polymers to address environmental challenges and promote green energy solutions. Structured into sections that cover historical context, materials development, and specific applications, the paper concludes with critical insights into current limitations and emerging trends, outlining promising directions for future research and commercial translation. This work aims to guide interdisciplinary efforts in material science and energy engineering toward the development of next‐generation polymer‐based energy solutions.