This book covers the current, state-of-the-art knowledge, fundamental mechanisms, design strategies, and future challenges in electrochemical energy storage devices using polymeric materials. It looks into the fundamentals and working principles of electrochemical energy devices such as supercapacitors and batteries and explores new approaches for the synthesis of polymeric materials and their composites to broaden the vision for researchers to explore advanced materials for electrochemical energy applications. All the chapters are written by leading experts in these areas making it suitable as a reference for students as well as provide new directions to researchers and scientists working in polymers, energy, and nanotechnology.