A high performance selectively grown nano-octahedral Mn3O4 on lignin derived laser scribed graphene for microsupercapacitor applications

Abstract

Porous graphene infused with mixed valency metal oxide as a supercapacitor material has received much attention. However, the existing approach to directly infusing mixed valency metal oxide such as Mn3O4 on graphene electrodes results in poor electrochemical performance. We report the facile fabrication of oil palm lignin derived laser scribed graphene with sol-gel hydrothermal grown nano-octahedral shaped Mn3O4 nanoparticles to boost the electrochemical performance of the flexible hybrid microsupercapacitor. The newly formed Mn3O4 nanoparticles (Mn3O4 NPs) were octahedral shaped and 15 to 30 nm in size, without any agglomeration and detrimental effect on the porosity of the laser scribed lignin-graphene. Further, the addition of Mn3O4 NPs grown for 3 h increased the specific surface area of the lignin-graphene by 66 %, which improved the microsupercapacitor's areal capacitance by five times to 136.19 mFcm−2 at 0.08 mAcm−2 measured in PAAS/K2SO4 gel electrolyte. The resulting highly stable and pliable microsupercapacitor retained 93.4 of its initial capacitances over 5000 charge-discharge cycles at 0.5 mAcm−2 and 97 % over 400 bending cycles at 50 mVs−1, respectively. The direct synthesis of Mn3O4 on IDE-patterned lignin-derived LSG electrodes presents new possibilities in energy storage applications.