Phenyl Disulfide Additive for Solution‐Mediated Carbon Dioxide Utilization in Li–CO2 Batteries

Phenyl disulfide (PDS) is employed as an electrolyte additive in lithium–carbon dioxide (Li–CO₂) batteries to allow for a solution‐mediated carbon dioxide reduction pathway. Thiophenolate anions, generated via electrochemical reduction of PDS, act as CO₂ capture agents by forming the adduct S‐phenyl carbonothioate (SPC^?) in solution. A mechanism of SPC^?‐mediated CO₂ capture and utilization is proposed and supported via carbon‐13 nuclear magnetic resonance spectroscopy and Fourier‐transform infrared spectroscopy. Reversible formation and decomposition of lithium carbonate and amorphous carbon during cycling, facilitated by the solution‐mediated pathway, are demonstrated with an array of characterization techniques. Li–CO₂ batteries employing the PDS additive show vastly improved capacity, energy efficiency, and cycle life. The enhanced Li–CO₂ battery performance offered by the proposed solution‐mediated reaction pathway offers a compelling step forward in the pursuit of reversible CO₂ utilization.