Liquid Madelung Potential as The “Beyond Debye-Hückel” Concept Validated for Several Metal Electrodes

Achievement of carbon neutrality requires the development of electrochemical technologies suitable for practical energy storage and conversion. In any electrochemical system, electrode potential <i>E</i> is the central variable that regulates the driving force of redox reactions. However, quantitative understanding of the electrolyte dependence of <i>E</i> has been limited to the classic Debye-Hückel theory that approximates the Coulombic interactions in the electrolyte under the dilute limit conditions. Therefore, accurate expression of <i>E</i> for practical electrochemical systems has been a holy grail of electrochemistry research for over a century. Here we show that the “<i>liquid Madelung potential</i>” (<i>E</i>_LM) based on the conventional explicit treatment of solid-state Coulombic interactions enables quantitatively accurate expression of the electrode potential, with the <i>E</i>_LM shift obtained from molecular dynamics reproducing a hitherto-unexplained huge experimental shift for the several metal electrode. Thus, a long-awaited method for description of the electrode potential in any electrochemical system is now available. Examples of battery system optimization based on this new concept will be demonstrated.