Circular and Bio‐Sourced Polymers for Energy Applications: Natural Feedstocks, Recycling, and Upcycling Routes

ABSTRACT The demand for sophisticated polymer materials has increased due to the quick development of energy storage and conversion technologies, which has also raised worries about resource depletion, the buildup of plastic waste, and environmental sustainability. As electrolytes, binders, separators, electrodes, and structural matrices, polymers are essential parts of contemporary energy devices. Nevertheless, the majority of them comes from feedstocks produced from fossil fuels and have a life cycle that is primarily linear. Incorporating developments in natural feedstock utilisation, polymer recycling and upcycling, and application‐specific material design, this paper provides a thorough and critical overview of circular and bio‐sourced polymer methods for energy applications. First, we go into bio‐sourced polymers made from renewable resources, emphasizing their molecular structures, methods of modification, and uses in batteries, supercapacitors, and other energy systems. Circular polymer techniques are next discussed, with a focus on recycling polymer components from wasted energy devices and upcycling plastic waste into higher‐value functional resources including electrolytes, separators, and electrode designs. The necessity of sustainable‐by‐design polymers, green processing technologies, and closed‐loop material systems is highlighted in the summary of existing issues and future prospects. In order to provide direction for the creation of intelligent polymer materials that enable high‐performance, long‐lasting, and environmentally friendly technologies, this review attempts to bridge the fields of polymer chemistry, electrochemistry, and sustainability science.