1.6 V high-voltage aqueous symmetric micro-pseudocapacitors based on two-dimensional polypyrrole/graphene nanosheets

Pseudocapacitive micro-supercapacitors (MSCs) have been regarded as miniaturized electrochemical energy storage devices with prominent features for seamless integrating wearable electronic devices. However, the electrochemical performance remains challenging due to the low voltage of aqueous electrolyte. Herein, we constructed aqueous pseudocapacitive MSCs ([email protected]) with a high operation voltage of 1.6 V using hybrid polypyrrole (PPy) and reduced graphene oxide ([email protected]) nanosheets working in 20 M LiCl gel electrolyte. The pseudocapacitive MSCs with interdigital planar geometry were manufactured by one-step mask-assisted filtration on a flexible substrate. The as-fabricated [email protected] in 20 M LiCl electrolyte showed higher areal capacitance of 44.5 mF/cm2 and improved areal energy density of 15.8 μWh/cm2, in comparison with the cell in 20 M LiTFSI electrolyte (35.7 mF/cm2, 12.7 μWh/cm2). Additionally, [email protected] exhibited excellent mechanical flexibility with 97% of initial capacitance retention at a bending angle of 180°, and superior integrated modular to boost voltage and current output. This work demonstrates that 2D pseudocapacitive materials hold a great chance for constructing high-performance MSCs.