Hyper-conjugated polyaniline delivering extraordinary electrical and electrochemical properties in supercapacitors

Conjugated polymers promise extremely-high theoretical supercapacitance to develop large capacitive storage devices. Existing conjugated polymers commonly realize their < 20% supercapacitance due to inferior electronic and electrochemical activities. Here we report hyper-conjugated effect to minimize energy level difference and carrier migration barrier in copolymerized polyaniline (PANI), a typical supercapacitive material. The hyper-conjugated effect efficiently promotes the elongation of conjugation system and the delocalization of π electrons. The largely increased number of free carriers in combination with the expanded range of carrier mobility guarantee 800% increments in electrical conductivity. Tests of symmetric supercapacitors with hyper-conjugated PANI show a high specific capacitance of 512 F g−1, excellent rate-capability and long-term cyclability. This work paves the way for designing conjugated polymers with remarkable electronic and electrochemical properties.