Binder-free laser induced graphene-MnO2 composite electrodes for high areal energy density flexible supercapacitors

The synthesis of Laser-Induced Graphene (LIG) through the laser ablation process of carbon-containing materials is a rapid and scalable process which enables the production of graphene in a cost-effective manner. In recent years, metal oxide – graphene composite electrodes have gained a lot of importance due to their use in various Energy Storage Devices (ESDs). In our investigation, we manufacture composite electrodes of manganese dioxide (MnO2) and LIG through a hydrothermal process and use it as electrodes in Flexible Supercapacitors. This method deviates from traditional procedures as it eliminates the requirement for binders in creating composite electrodes, given that MnO2 can be directly deposited onto the LIG electrodes. The assembled all-Flexible Supercapacitor (FSC), featuring unique LIG-MnO2 composite electrodes, showcased a remarkable areal capacitance of 66.5 mF cm−2 at 5 mV s−1 scan rate. The device also exhibited a very high areal energy density (2.3 mWh cm−2) and power density (19.7 mW cm−2) at 0.2 mA cm−2 current density. Also, 82% capacitance retention was observed at the end of 2000 cycles and the device also exhibited a good flexibility during bending tests, as evidenced by an 80% capacitance retention after 100 bending cycles.