Laser direct preparation and processing of graphene/MnO nanocomposite electrodes for microsupercapacitors

Abstract

Graphene/metal oxide nanocomposites are one of the most ideal electrode materials for microsupercapacitors (MSCs). However, the efficient and simple synthesis of graphene/metal oxide nanocomposites and fabrication of microelectrodes for MSCs are a challenge. In this work, using graphene oxide/Mn(CH3COO)2 as the precursor, an efficient and simple approach is proposed to simultaneously synthesize graphene/MnO nanocomposites and process interdigital electrodes for MSCs by one-step picosecond laser direct-writing. Here, the MnO nanoparticles that are evenly distributed on the surface of graphene can provide pseudocapacitance to enhance the specific capacitance of graphene/MnO nanocomposites. Specifically, graphene/MnO electrode exhibits a high specific capacitance of 470 mF cm−2. Furthermore, based on graphene/MnO interdigital electrodes, the symmetric MSCs shows excellent electrochemical performance. The maximum area specific capacitance of MSCs with PVA/H3PO4 gel electrolyte is 55 mF cm−2. After 5000 cycles, the capacitance of the MSCs with PVA/H3PO4 gel electrolyte retains about 96% of its initial capacitance. The maximum energy density of MSCs with PVA/H3PO4 gel electrolyte is 4.89 μWh cm−2, and its maximum power density is 0.72 mW cm−2. Moreover, this approach also provides a way to synthesize other graphene/metal oxide nanocomposites for MSCs by one-step laser direct-writing.