A Review of Tailoring Polyaniline Ionic Liquids for Long Cycle-Stable Supercapacitors with High Capacitance

Polyaniline (PANI) with tunable morphology was synthesized in ionic liquids to overcome the short cycle life of PANI-based electrodes materials for supercapacitors. It was found that the ionic liquids perform the role of a “soft” template agent and a dopant agent in the polymerization medium of PANI thanks to the non-covalent interactions between the ionic liquids and the PANI. These functions of ionic liquids lead to well-organized nanostructured morphology of PANI and an improvement of PANI-electrode wettability, and thus enhanced electrochemical performances and cycle life stability of PANI-based electrodes. However, the ability of ionic liquids in performing their role either as a soft template or as dopant agent during the PANI synthesis is largely affected by the structure of ionic liquids (head group, alkyl chain length, anion structure, and so forth). This work covers the most relevant studies on the mixing characteristic of PANI and the ionic liquids to gain an insight into the contribution of ionic liquids in controlling the morphology and the related properties of PANI.