Conducting polymer composites for unconventional solid-state supercapacitors

The rapid development of wearable devices has stimulated the pursuit of unconventional and multifunctional flexible supercapacitors such as stretchable, compressible, electrochromic, self-healable or transparent supercapacitors. Redox-active conducting polymers (CPs) that combine metal like electrically conductive properties with polymer like mechanical properties are ideal materials for use. However, they suffer from poor performance due to volume variations during charge and discharge processes. The integration of CPs with other materials to form composites provides an effective approach to achieve excellent performance. This review discusses the recent progress on the design and fabrication of CP composites with tailored microstructures for these novel supercapacitors. It will cover a wide range of materials with different intrinsic properties (e.g. carbon materials, metal oxides/hydroxides, and two dimensional materials) to be incorporated with CPs. It aims to provide insights into the synergistic effect of components on the supercapacitive performance of composites. We also present the strategies towards their practical applications in integrated systems and future perspectives.