Preparation of starch-based porous carbon electrode and biopolymer electrolyte for all solid-state electric double layer capacitor.

An ever-increasing demand for energy coupled with environmental pollution associated with conventional energy production continues to drive the search for alternative renewable energy storage solutions. In this regard, a high surface area (1841 m2 g-1), hierarchically porous (∼1.18 cm3 g-1) and self-inherited nitrogen (2.1 at.wt%) based activated carbon are obtained from Artocarpus heterophyllus seed derived starch as a result of ZnCl2 chemical activation. A flexible, conductive, thermally stable and bio-degradable biopolymer electrolyte film is prepared from Manihot esculenta starch powder. These eco-friendly hierarchically porous architectured carbon electrode and flexible biopolymer electrolytes are employed as significant components in a coin cell-based all-solid-state supercapacitor. The resulting device delivers a high specific capacitance of 240 Fg-1 at 0.5 mA with 97% coulombic efficiency over 2000 cycles. In addition, the device provided excellent specific energy (17 Wh kg-1) and specific power (3823 W kg-1). Interestingly, the starch derived biopolymer electrolyte film, when buried under soil, shows a favourable natural rate of degradation. Therefore, this fabricated electric double layer capacitor can be used as a promising device with little to no potential environmental harm.