Flexible Micro Supercapacitor Based on Laser Scribed Graphene (LSG)

In the present work, graphene powder has been synthesized by laser scribing method. The resulted flexible light-scribed graphene is very appropriate to be utilized as micro-supercapacitors .Graphene conducts electricity and heat better than anything else and has combination of unique optical and mechanical properties. Electrons have nobilities in graphene over a hundred times those in silicon. In the present work we used a standard optical LightScribe DVD drive to directly do the laser reduction of graphene oxide (GO) films to graphene. GO was prepared by the modified Hummers' method as reported elsewhere. Briefly, 2 g graphite powders were added to a mixture of 1 g NaNO3 and 46 ml H2SO4 and the mixture was cooled to 10 °C using an ice bath. In the next step, 6 g KMnO4 was gradually added to the solution and the reaction temperature was maintained below 20 °C. The mixture was then stirred at 35 °C for 2 h. The resulting solution was diluted by adding 92 ml of deionized water until a dark brown suspension was obtained. Then, the solution was treated by adding 340 ml H2O2 solution. Finally, a uniform suspension of GO nanosheets was obtained by adding water to the resulting precipitate and 12 h of sonicating. The resulting suspensions were uniformly drop casted on a LightScribe DVD disk and then dried under the air at an ambient temperature. The GO coated DVD disk was placed in a LightScribe DVD drive with a wavelength of 780 nm. Raman result confirm that the laser irradiation properly reduce GO to graphene sheets. The structure of graphene arrays were studied by SEM images the results indicated that the laser based reduction was a useful method to production graphene layers. The CV curves of pristine rGO at various scan rates showed that the ultimate product has the power of storing energy in a supercapacitor level. Finally, the long-term charge-discharge stability of the LSG has been plotted which indicates that specific capacitance has decreased very slightly from its primary capacitance of ~ 10 F cm-3 and its cyclic stability is favorable over 1000 cycles.