Rational-design of polyaniline cathode using proton doping strategy by graphene oxide for enhanced aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have been of excellent interest in the latest years due to their environmental benignity and easy preparation. One vital barrier to the production of high-performance ZIBs is the development of appropriate cathode materials. Polyaniline (PANI) is very promising, particularly due to its excellent conductivity and easy preparation, among varied cathode materials. However, deprotonation of PANI is a key problem greatly deteriorating capacity and cycling stability of PANI cathode. In this study, we discover that graphene oxide (GO) can fix the problem effectively as the wealthy functional GO oxygen groups can provide a local proton reservoir that increases PANI protonation. As a result, the GO composited PANI electrodes show significantly improved zinc-ion storage performance than pure carbon composited PANI cathodes. Specifically, the battery performances in terms of capacity (233 mA h g−1) and rate performance (100 mA h g−1 under 5 A g−1) are enhanced significantly after introducing GO into PANI cathode. Besides, flexible PANI-based ZIB devices can be easily fabricated owing to the excellent film-forming property of GO. This work offers new insight for improving PANI cathode materials by carbon chemistry.