Effective design of MnO2 nanoparticles embedded in laser-induced graphene as shape-controllable electrodes for flexible planar microsupercapacitors

Abstract Flexible planar microsupercapacitors (MSCs), with the advantages of small size, easy integration and expansion on electronic devices, have emerged as one of the most critical power devices in wearable and portable electronics. However, most processes involve independent preparation of electrode materials, patterned microelectrodes, and subsequent modular integration, making the steps very complicated. Herein, we have developed a novel, simple and one-step laser direct writing process to design planar shape-controllable MnO2 nanoparticles evenly embedded in laser-induced graphene (MnO2/LIG) MSCs on different flexible substrates. The obtained MnO2/LIG MSCs show an outstanding areal specific capacity of 15.04 mF cm−2, a high energy density of 1.22 mWh cm−2 at a good power density of 1.278 mW cm−2, good mechanical flexibility and remarkable modular integration due to effective design of pseudocapacitive MnO2 nanoparticles evenly embedded in highly conductive LIG with 3D porous structure. This universal manufacturing route for controllable assembly of flexible planar MSCs with other pseudocapacitive nanoparticles embedded into LIG, thus broadening their flexible and wearable application as a promising storage device to meet the modular integration and biocompatibility.