Microstructure control for high-capacitance polyaniline

• Ionic crosslinking can improve the ordering and interplanar spacing of polyaniline. • Further enlarge the interplanar spacing of polyaniline via a simple heat treatment. • The as-prepared polyaniline has nearly quadrupled the specific capacitance. • This new form polyaniline exhibits excellent rate performance. Polyaniline (PANI) with high theoretical specific capacitance demonstrates a broad application prospect in supercapacitors, but the fact that the disorder and entanglement based on abundant one-dimensional polyaniline chains lead to low actual specific capacitance and poor rate capacity. In this work, ionic crosslinking can effectively control the randomly oriented chain growth and the degree of polyaniline aggregation through simply replacing the connector. The degree of oxidation, conjugation length and π-π stacking of polyaniline chains were increased, causing more plane accumulation on or between the molecular chains. The polyaniline structure tends to be ordered, which provides more active sites for the Faraday reaction, and after heat treatment, the ion transport channel of the prepared material is further expanded, exhibiting four times the specific capacitance of in situ polymerized polyaniline as well as excellent rate performance. The symmetrical supercapacitor displays a considerable energy density and fine integration capability. Such results suggest that ionic crosslinking provides the possibility to prepare high-performance supercapacitor electrode materials. A new form of polyaniline based on ionic crosslinking can efficiently improve the ordering and interplanar spacing, which facilitated the contact between electrode material and electrolyte, and thereby exhibiting excellent specific capacitance and rate performance.