Nanostructured Polypyrrole as a flexible electrode material of supercapacitor

Polypyrrole (PPy), as one of the conducting polymers, has emerged as a promising active material for high performance supercapacitor owing to its intrinsic characteristics (e.g. high electrical conductivity and interesting redox properties). It’s attracting more and more attentions with the development of flexible/wearable devices thanks to the great flexibility and ductility of PPy as a polymer. This review presents a comprehensive understanding on synthesis, morphology control, electrochemical performances and solid-state devices of the nanostructured PPy and its nanocomposites. In the past decades, a variety of nanostructures, including one-, two-, and three-dimensional, have been designed and fabricated via different methods, demonstrating a great potential for the application as supercapacitor electrodes. Thereafter, many nanostructured PPy-based supercapacitors with different macroscopic configurations have been presented aiming to achieve better electrochemical performance, and some representative ones, for example, flexible and/or wearable supercapacitors, are summarized in this review. Cycling stability is another critical issue that determines its practicability of the PPy-based devices. Solutions to improve cycling performance and mechanisms behind are also discussed. Last, perspectives for the future development in nanostructured PPy-based supercapacitors are described. This review gives a summary of selected contributions which we hope to provide readers with a better understanding of the fast developing field of PPy-based supercapacitors.