Long cycle life achieved in polyaniline/SP based self-healing supercapacitor

Polyaniline (PANI) has emerged as a promising electrode material for supercapacitors due to its low cost and high specific capacitance. However, during the charge and discharge process, PANI undergoes volume changes, leading to structural damage at the molecular level. This results in material pulverization, causing a loss of electronic contact with the electrode and, consequently, a decrease in capacitance. In this study, we employed ultrasonication-assisted growth of PANI on super-P (PANI/SP-US) to enhance the structural stability. At 1 A g⁻¹, a high specific capacitance of 639 F g⁻¹ was achieved. After 5000 charge-discharge cycles at 2 A g⁻¹, the material retained 75.9% of its capacitance. More importantly, we further developed an effective strategy to incorporate a self-healing polymer (SHP) to fabricate a self-healing electrode. Due to the self-healing ability, the pulverized PANI/SP-US was able to be reconnected and restore electronic contact with the electrode substrate, thereby regaining specific capacitance and achieving excellent cycle life. The sphere-like shape of PANI/SP-US is also of benefit to the self-healing process. Symmetric and asymmetric self-healing devices based on PANI/SP-US and the self-healing polymer exhibited outstanding cyclic stability, retaining 107.9% and 108% of their capacitance, respectively, after 10,000 cycles at 2 A g⁻¹. The self-healing device also exhibits good flexibility under bending, folding deformations. In addition, the device also shows good capacitance retention as the temperature shifted from 50°C to 0°C. This work underscores the significance of microstructure self-repair in enhancing cyclic stability and extends the application of self-healing devices to flexible and variable-temperature conditions.