Abstract
Nanofibers have emerged as transformative materials in the field of energy storage, offering unique physicochemical properties such as high surface area, porosity, and tunable morphology. Recent advancements have also introduced genetically modified fibers-engineered at the biological level to produce functionalized nanostructures with customizable properties. These bioengineered nanofibers add a sustainable and potentially self-healing component to energy storage materials. This paper reviews key applications of conventional and genetically modified nanofibers in lithium-ion and sodium-ion batteries, supercapacitors, hybrid systems, and flexible energy storage with a focus on how genetic and molecular engineering of fibrous materials enables new capabilities in ion transport, electrode architecture, and device longevity. Together, these advances contribute to the development of next-generation energy storage systems with enhanced performance, biocompatibility, and sustainability. This review therefore critically examines the current state, advantages, and limitations of both synthetic and biopolymer-based materials in energy storage applications. It discusses recent technological innovations, such as polymer-nanoparticle composites, functionalized polymer matrices, and next-generation polymer electrolytes. Future research should prioritize enhancing conductivity, improving scalability, and reducing environmental impact, ensuring that polymer-based materials contribute to the development of more efficient and sustainable energy storage technologies.