Fabrication of high cycling stability flexible micro-supercapacitor using electrodeposited polyaniline-nitrogen sulphur doped carbon dot binary nanocomposites

Micro-supercapacitors fabricated using polyaniline are ideal for the energy requirements in flexible and wearable electronic devices. Their drawback of low cycling stability due to swelling can be minimised using nanocomposites of polyaniline. This work aims to fabricate a micro-supercapacitor using electrodeposited polyaniline-carbon dot nanocomposite and validate its capacitive performance. Nitrogen and sulphur co-doped carbon dots synthesised via the hydrothermal method showed a high quantum efficiency of 70.02 % with respect to quinine sulphate in sulfuric acid medium. Electrodeposited PANI/N-S doped carbon dot binary nanocomposite showed an areal capacitance of 990 mF cm^-2, which is much higher compared to pristine PANI with 754 mF cm^-2. Two-electrode symmetric micro-supercapacitor fabricated using PVA-H₂SO₄ gel electrolyte showed an areal capacitance of 276.9 mF cm^-2 at 0.4 mA cm^-2 with a high energy density of 24.6 µWh cm^-2 and a power density of 0.17 mW cm^-2. In addition to this, the fabricated device exhibited excellent cycling stability with 98.49 % capacitance retention even after 15000 cycles. The device also showed 93.3 % capacitance retention even after 2000 bending cycles. Thus, the fabricated micro-supercapacitor can contribute to flexible as well as portable electronic applications, as the need for miniaturized energy storage devices is in high demand.