The value of Δ𝜙 is, as expected, most negative at 𝐶 sup = 0 (Figure ), where Δ𝜙 almost cancels the 𝐸 -𝐸°r ds ′ value leading to the linear response. The Δ𝜙 is a certain magnitude even at 𝐶 sup = 100 . This is surprising as it is often considered sufficient to add a supporting electrolyte at a concentration 100 times that of the reactant. This would be the result of a combination of the low self-supporting effect of the reactant/product (Fc + /Fc) being monovalent and electrically neutral, and the low diffusion coefficient of the supporting electrolyte of LiPF6 in PC. parameters are: 𝑘 0 =1.7 ×10 -4 m mol s -1 , 𝑐 A = 1 mM, 𝑐 B = 0 mM, 𝐷 Fc += 4.2 × 10 -10 m 2 s -1 , 𝐷 Fc = 3.6 × 10 -10 m 2 s -1 , 𝐷 Li + = 2.166 × 10 -10 m 2 s -1 , 𝐷 PF 6 -= 4.681 × 10 -10 m 2 s -1 ,