As reported in Table , we observe that V increases with substitution of metals with Al, as shown by the difference in voltage for NMF (3.01 V) and NMA (3.60 V), and FTV (4.56 V) and FTA (3.02 V). This is a significant increase of at least 20%, which agrees with previous research. We return to this trend, and offer chemical insight into its origin, after completing electronic structure analysis.