Addendum to “On the exploitability of thermo-charged capacitors” [Physica A 390 (2011) 482–491]

In the article [Physica A 390 (2011) 482–491], an explicit discussion on contact potential (and its alleged consequences) arising between the inner metallic sphere of a thermo-charged spherical capacitor and its Ag–O–Cs coating is missing. This addendum aims to clarify this issue.