The 𝐸°′ was determined by measuring the equilibrium potential in PC solutions of 1 mM FcPF6 +1 mM Fc in the presence of 0, 1, 10, 100 or 1000 mM LiPF6. The diffusion coefficients of Fc and Fc + were determined with the Cottrell equation from potential step amperometry in 1mM FcPF6 + 1 mM Fc in the presence of 100 or 1000 mM LiPF6 at 𝐸°′ ± 0.25 V.