Tailoring polyaniline with dual dopant engineering as a high efficiency cathode material for aqueous zinc ion batteries.

Aqueous zinc-ion batteries (AZIBs) are considered a promising green energy storage system due to their environmental friendliness, intrinsic safety, and low cost. However, cathode materials still face significant challenges in practical applications due to unsatisfactory energy storage properties. Among conducting polymers (CPs), polyaniline (PAni) is regarded as the most promising candidate because of its ease of synthesis, environmental stability, adjustable electrical conductivity, and doping and de-doping chemistry. To enhance its rate capability and cyclic stability, co-doped PAni was synthesized through chemical oxidative polymerization using sulfuric acid and the anionic surfactant sodium dodecyl sulfate (SDS). The anionic surfactant also acts as a doping agent for the PAni polymer, serving as a secondary dopant. This co-doping strategy results in co-doped PAni with higher conductivity and an interconnected fibrous morphology. Electrochemical results demonstrate that co-doped PAni, when used as a cathode in coin cell AZIBs, delivers an excellent specific capacity of 200.74 mAh g at 0.5 A g and retains 153.08 mAh g at 5 A g. More importantly, it exhibits exceptional cyclic stability, with capacity retention of 89.25 % and 89.60 % after 10,000 galvanostatic charge-discharge (GCD) cycles at current densities of 5 A g and 7 A g, respectively. This work demonstrates the feasibility of co-doped PAni and provides an excellent option for developing high-performance cathode materials, which are urgently needed in the field of ZIBs.