Bilayered microelectrodes based on electrochemically deposited MnO2/polypyrrole towards fast charge transport kinetics for micro-supercapacitors

Micro-supercapacitors (MSCs) are promising power solution facilities for miniaturized portable electronic devices. Microfabrication of on-chip MSC with high specific capacitance and high energy density is still a great challenge. Herein, we report a high-performance MnO2/polypyrrole (PPy) microelectrode based MSC (MnO2/PPy-MSC) by modern micromachining technology. Interdigital Au micro current collectors were obtained by photolithography, physical vapor deposition and lift off. A layer of PPy was electrochemically deposited on Au current collectors followed by deposition of urchin-like MnO2 micro/nanostructures. The electrochemical performance of MnO2/PPy-MSC was explored employing LiClO4/PVA gel electrolyte. The assembled MSC demonstrated a high areal capacitance of 13 mF cm−2, an energy density of 1.07 × 10−3 mW h cm−2 and a power density of 0.53 mW cm−2. In addition, the MnO2/PPy-MSC showed an improved cycling stability, retaining 84% of the initial capacitance after 5000 CV cycles at a scan rate of 500 mV s−1. Our proposed strategy provides a versatile and promising method for the fabrication of high-performance MSCs with large-scale applications.