Expanding the Cathodic Potential Window of Activated Carbon Electrodes in a Lithium‐Salt Containing Electrolyte

Abstract Activated carbon is the most common material used for electrochemical double layer capacitors. With the recent development of Li‐ion capacitors, activated carbon is also used in Li‐salt‐containing organic electrolytes. The cathodic potential of activated carbon is in general limited to 1.5 V vs. Li/Li + , in order to avoid the decomposition of the electrolyte, which can block the porosity and accessible area of the carbon. This work aims to investigate the unexplored region, below 1.5 V vs. Li/Li + to understand how a lower limit cut‐off can influence the electrochemical performance of activated carbon. Interestingly, a very critical potential is 1.0 V. When an electrode is cycled until this limit, the performance drastically falls down. On the other side, by further expanding the lower potential limit to 0.5 V, the capacity increases, without substantially compromising the resistance and the cycling stability. At even lower potentials (i. e., 0.2 V, 0.1 V and 0.005 V) the capacity further increases, but at the cost of the cycling stability. This work opens new directions on the use of activated carbon at potentials below the standard cathodic limit of 1.5 V vs. Li/Li + .