Zn-Doped and CNTs-Incorporated Polyaniline as High-Performance Cathode for Aqueous Zinc-Ion Batteries

Polyaniline (PANI) has good electrical conductivity, diverse redox chemistry, and a unique doping/dedoping mechanism. Furthermore, the facile synthesis, controllable morphology, and the ability to grow in situ on substrates provide the impetus to obtain aqueous Zn-ion batteries (ZIBs) with PANI as a cathode. However, due to its poor redox reversibility in a near-neutral electrolyte environment, the resulting ZIBs have a rapid capacity drop, poor rate performance, and poor cycling stability. To improve the electrochemical performance of PANI cathodes in ZIBs, zinc ions are doped into PANI and incorporated with carbon nanotubes (CNTs) by one-step polymerization. The results show that the use of Zn-doped PANI and CNTs composites can enhance the conductivity and stability of PANI, and further improve the capacities, rate performances, and cycle life of the ZIBs. The battery assembled with an optimized PANI-based cathode exhibits a high specific discharge capacity of 156.7 mAh g(-1) at 0.05 Ag-1, and excellent capacity retention of 95% after 800 charge/discharge cycles. Additionally, the Zn//PANI battery shows a promising energy density of 166.7 Wh kg(-1), together with a power density of 111.2 W kg(-1). Such Zn ion-doped PANI-CNTs cathode material may provide significant insight into future large-scale industrial production for Zn//PANI batteries.