Estimation of energy efficiency in neptunium redox flow batteries by the standard rate constants

The light actinide has two kinds of the isostructural redox couple, An(4+)/An(3+) and AnO(2)(2+)/AnO(2)(+). The battery with these couples is expected to be excellent energy efficiency due to the rapid electrode reactions. In the present paper, the standard rates for Np4+/Np3+ and NpO22+/NpO2+ electrode reactions were evaluated by the cyclic voltammetry and the energy efficiency in the neptunium battery was estimated from the standard rate constants. As a result, the efficiency is found to be excellent. Moreover, the uranium battery with U4+/U3+ and UO22+/UO2+ couples is expected to be feasible in the aprotic solvents. (c) 2004 Published by Elsevier Ltd.