Waste‐Derived Activated Carbon for Supercapacitors: Current Trends and Future Prospects

The primary challenge for supercapacitor technology lies in achieving battery‐level performance while reducing costs. Enhancing energy density involves strategic adjustments such as increasing capacitance, reliance on electrode–electrolyte interactions, or boosting cell voltage, dependent on electrolyte stability. Thus, optimizing energy density requires careful electrode material design and electrolyte selection. Because of their abundant availability, exceptional performance, and simple processing methods, various naturally occurring bio‐wastes and industrial wastes have been explored for the production of activated carbon for supercapacitors. Additionally, agricultural by‐products such as sugarcane bagasse, rice husk, tea waste, coconut shell, peanut shell, lotus stem, and hemp fiber show promise as raw materials for graphene synthesis. Life cycle assessments beyond greenhouse gas emissions and energy efficiency, along with calibrated evaluation techniques and techno‐economic analyses, are essential for meaningful sustainability comparisons. The rapid expansion of the bioenergy sector underscores the need for responsible management and sustainability evaluations. This article emphasizes the potential of waste‐derived activated carbon as a sustainable and efficient electrode material for supercapacitors.