Enhanced the zinc ion storage performance of PANI in ZnSO₄ aqueous electrolyte by doping with sulfonated graphene quantum dots

Polyaniline (PANI) is a kind of low-cost and sustainable electrode material for large-scale aqueous zinc ion batteries. However, PANI always shows poor cycling performance because of deprotonation in cheap weakly acidic electrolytes. In this work, we find that sulfonated graphene quantum dots (SGQDs) dopant can alleviate the above-mentioned problem effectively because the -SO3- groups on the SGQDs can act as a local proton reservoir and increase the protonation of PANI. When tested as zinc ion cells in ZnSO4 aqueous electrolyte, the SGQDs doped PANI electrodes exhibit excellent rate performance (115 mA h/g at 1 A/g and 105 mA h/g at 5 A/g) and good cycling stability (retain 81% after 1500 cycles), which are much better than that of pure PANI. Furthermore, the chemical oxidation method used to prepare powdered PANI is easy to scale up. This work provides a potential strategy for enhancing the Zn-ion storage performance of PANI in cheap weakly acidic electrolytes by versatile carbon quantum dots materials.