Blending of Activated Low-Grade Coal Powder with Coconut Shell Waste for Supercapacitor Applications

Activated carbons (ACs) are the key components for supercapacitors due to their several advantages including abundant availability, low cost, ease of fabrication, and controllable physico-chemical properties. In recent times, the investigation on the relationship between supercapacitor performances and the morphology, texture, and dimensions of different types of activated carbons is becoming essential to optimize the best energy storage devices. The main objective of the current study is to create an improved activated carbon material by blending low-grade coal powder (subbituminous rank available in Northeast India) and waste coconut shell-based activated carbon at different weight ratios to use as indigenous supercapacitor electrode materials. The mixed-blend improved ACs exhibit excellent electrochemical performance (specific capacitance of 251.67 F g–1 at 0.5 A g–1) as compared to the commercially available AC sample. The prototype supercapacitor (45.6 cm2 pouch cell configuration) fabricated by using the blended coal- and coconut shell-based activated carbons shows an estimated capacitance of ∼30 F at 2.7 V in an organic electrolyte (1.5 M TEABF4 in ACN) with cellulose paper-based separators (TF40-30; NKK). It was also observed that the fabricated prototype supercapacitor is capable of lighting an LED (32 mW) for an entire hour, demonstrating a promising future in high-performance and low-cost energy storage technologies.