Experimental and Computational Analysis of the Solvent‐Dependent O₂/Li⁺‐O₂⁻ Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium–Oxygen Batteries

Abstract

Abstract Understanding and controlling the kinetics of O 2 reduction in the presence of Li + ‐containing aprotic solvents, to either Li + ‐O 2 − by one‐electron reduction or Li 2 O 2 by two‐electron reduction, is instrumental to enhance the discharge voltage and capacity of aprotic Li‐O 2 batteries. Standard potentials of O 2 /Li + ‐O 2 − and O 2 /O 2 − were experimentally measured and computed using a mixed cluster‐continuum model of ion solvation. Increasing combined solvation of Li + and O 2 − was found to lower the coupling of Li + ‐O 2 − and the difference between O 2 /Li + ‐O 2 − and O 2 /O 2 − potentials. The solvation energy of Li + trended with donor number (DN), and varied greater than that of O 2 − ions, which correlated with acceptor number (AN), explaining a previously reported correlation between Li + ‐O 2 − solubility and DN. These results highlight the importance of the interplay between ion–solvent and ion–ion interactions for manipulating the energetics of intermediate species produced in aprotic metal–oxygen batteries.