Triple enhancement of polyaniline nanofiber growth through flowing seed polymerization for boosting charge storage capacity of flexible supercapacitor

With the rapid development of smart wearable and portable devices, intense attention has been focused on the fabrication of flexible and lightweight materials. A novel approach of flowing seed polymerization is proposed in this work to promote the growth of polyaniline (PANi) towards high energy density supercapacitors. Herein, the triple enhancement on the oriented growth of the nanofibers could be achieved through strongly inter−chain doped aniline oligomer seeds with natural organic acid formed by dilution polymerization and subsequent strong intra−chain interaction of PANi formed in strong acidic solution as well as the confined effects within the tube under flowing condition. The effects of four kinds of natural organic acids including phytic acid, citric acid, malic acid and oxalic acid on the morphologies, microstructures and electrochemical behaviors of PANi products are investigated. It is found that the usage of natural organic acid could bring a great influence on the formation and charge storage capacity of PANi nanofibers. Benefiting from more compact nanofiber structure and higher electrical conductivity, the OA−PANi nanofiber−based device possessed the maximum energy density of 30.0 Wh kg−1 at a power density of 601.7 W kg−1 with high capacitance retention of 82.8 % after 5000 cycles. This simple and green approach is developed for the continuously scalable fabrication of PANi nanofibers as high−performance electrode materials, which is essential to meet the demand on flexible supercapacitors with high energy density for the future wearable electronics.