Interfacial binary doping strategy to achieve high capacity and cyclic stability in polyaniline cathodes for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) offer safe and environmentally friendly features, making them attractive energy storage devices. A critical challenge in the development of AZIBs is the search for cathode materials capable of delivering stable and efficient performance. Therefore, the quest for reliable cathode materials has become a pressing priority for advancing this technology. Conductive polyaniline (PANI) is a favorable candidate due to its excellent electrical conductivity, diverse redox chemistry, and doping-de-doping mechanism. To boost the electrochemical performance of PANI as a cathode in ZIBs, we fabricated a binary doped PANI using H 2 SO 4 and ammonium lauryl sulfate (ALS). The synergy of the binary doping approach endows H 2 SO 4 /ALS-PANI with good conductivity, better structure and morphology. As a result, binary doped PANI demonstrates robust electrochemical performance in AZIBs. In a full Zn cell, the H 2 SO 4 /ALS-PANI cathode exhibited an exceptional specific capacity of 269.58 mAh g -1 at 0.5   A   g -1 and retained 223.52 mAh g -1 at 5   A   g -1 , showing excellent rate performance (82.91%). Moreover, it demonstrated promising cyclic stability with 97.68% capacity retention after 4,000 galvanostatic charge-discharge (GCD) cycles, maintaining coulombic efficiency (CE) close to 100%. Electrochemical impedance spectroscopy (EIS) indicate that H 2 SO 4 /ALS-PANI has low charge transfer resistance (R ct ). This study provides inspiring dual doping strategy for developing conducting polymers electrode materials for AZIBs.