On the Selection of the Current Collector for Water Processed Activated Carbon Electrodes for their Application in Electrochemical Capacitors

Electrode manufacturing for electrochemical energy storage technologies often relies on hazardous fluorine‐containing compounds and toxic organic solvents. To align with sustainability goals and reduce costs, there is a pressing need for water‐processable alternatives. These alternatives can halve electrode processing costs and ease regulatory burdens. While progress has been made with water‐processed graphite electrodes using eco‐friendly binders, challenges persist for high‐mass loading activated carbon (AC) electrodes. This study investigates the impact of modified aluminium current collectors on water‐processed AC electrodes, focusing on compatibility, processability, and electrochemical performance. Various aluminium foils, including etched and carbon‐coated types, were evaluated. The results show that modifications at the interface significantly improve the wetting properties and mechanical stability. Electrochemical tests revealed that carbon‐coated aluminium provided the lowest internal resistance and highest rate capability due to intimate contact between the electrode components. In contrast, etched aluminium foil exhibited higher contact resistance and poorer performance. Ageing studies demonstrated that carbon‐coated foils maintained better electrochemical performance over time, as the carbon layer reduced degradation reactions and contact resistance. These findings suggest that uniformly carbon‐coated aluminium current collectors are the optimal choice for high‐power electrochemical capacitors, balancing performance, sustainability, and cost‐efficiency.