Scalable synthesis of micro@meso porous carbon using crop-waste as cost-effective electrode materials for energy storage

Development of recycling pathways to produce sustainable and high-surface area carbon materials using crop-waste biomass is highly desirable for the design of cost-effective energy storage devices. In this study, three different activated carbon-based materials for supercapacitor application were prepared via simple metal halide activation on crop- waste biomass, specifically from the banana plant derivatives. The prepared samples with the single step activation show exceptional high surface area and large porosity, which are essential for elevating the energy storage performance. Among the different samples developed, stalk-derived activated carbon shows the highest surface area of 1311 m²/g and the average pore diameter of 1.77 nm. Nevertheless, all the samples constitute of three different porosities including micro-, meso-, and macro-pores responsible for the energy storage application. When tested for flexible electrode using porous carbon coated hydrophilic carbon cloth in symmetric supercapacitor, the device exhibits high specific/areal capacitance of 166.3 F/g/415.7 mF/cm² at a current density of 3 mA/cm² with exceptional cycling stability of 94% retention after 10,000 cycles. Moreover, the symmetric supercapacitor device enables the maximum energy and power densities of 17.2 Wh/kg and 2214 W/kg, respectively. This simple approach illustrates the utilization of biomass waste as an inexpensive resource for the development of energy storage devices with high energy density and power densities.