After drying, circular electrodes were cut from the carbon film using a steel punch (0.5 inch diameter). Each electrode was cut to achieve a mass within 10% of 15 mg, and trimmed down if necessary (e.g. due to uneven film thickness). The mass of each electrode was recorded three times, with the mass recorded as the mean of the measurements and the error as the deviation from that mean. Filter paper (Whatman 55 mm Cat No. 1001-055) was used for a separator, cut into a circle slightly less than the diameter of the current collector. This minimized chances of a short circuit, such as from a misaligned electrode or bending titanium mesh contacting the opposite current collector.