Recent progress in conductive polymers for advanced fiber-shaped electrochemical energy storage devices
Over the past decades, flexible and wearable energy storage devices have received tremendous interest due to the development of smart electronic products, such as Apple Watch, Google Glass, and sport wristbands. Fiber-shaped electrochemical energy storage devices (FEESDs) derived from fibrous electrodes are standing out as a result of the excellent flexibility and breathability compared with the planar counterparts. Textiles and fabrics can be simply achieved by spinning and weaving FEESDs, which perfectly match with an arbitrary uneven and mobile surface, revealing enormous potentialities in wearable electronics. Combining mechanical features with the electrically conductive properties and biocompatibility, conductive polymers (CPs) have emerged as a promising candidate for smart textile products including medical textiles, protective clothing, touch screen displays, and flexible fabric power supplies. In this context, this review summarizes the material design of CPs for fibrous electrodes and provides a critical discussion on their applications in flexible energy storage devices. Meanwhile, basic principles are briefly presented, including the conduction mechanism of conductive polymers, fibrous electrode design, and the evaluation of the electrochemical/mechanical performance for fibrous devices. Last, possibilities and challenges for the development of CP derived FEESDs are outlined as well.