Calculations of oxidation potentials of redox shuttle additives for Li-ion cells

The oxidation potentials of seventeen molecules used as candidate shuttle additives in Li-ion cells were calculated using density functional theory and compared with experiment. The root-mean-square deviation between the calculated and measured oxidation potentials of these seventeen molecules is 0.15 V with the maximum deviation being 0.25 V, indicating that the ab initio calculation is in good agreement with the experiment. Neglecting thermal contributions in the calculation of standard oxidation potentials at ambient conditions does not lead to significant errors. An empirical relation between the oxidation potentials and the orbital energies of these molecules in solution is presented. The oxidation potential of a molecule could be estimated based on the orbital energy of the molecule's highest occupied molecular orbital or its cation's lowest unoccupied molecular orbital in solution with an error less than 0.3 V for most molecules reported. (c) 2006 The Electrochemical Society.