where mave is the average mass of one electrode in the cell (mave = ½ (me,1 + me,2)). Cg,1 has units of F g -1 . This interpretation results in a specific capacitance value four times greater than the previous interpretation. However, it must be noted that Equation assumes that the capacitances of the positive and negative electrodes are equal. Although this may not be the case in practice, the value obtained from Equation 4 will still give an indication of the performance of a device and is often quoted in literature, as seen from the fact that 36 -37% of the groups in this study reported Cg,2. We recommend that three-electrode measurements are also performed to independently evaluate the capacitance of both the positive and negative electrode independently in their respective operating potential windows. Derivations for Equations 3 and 4 are stated in the Supplementary Information (SI Section 2).