Calculations of the Electrolyte Oxidation Stability

While DFT calculations often reprodnced experimentally observable trends for the oxidation stability of anions [17,19] and solvents [7,18,21,24, 39], they often failed to quantitatively relate the calcnlated oxidation potential for numerous electrolytes and experimentally measnred data. For example, the intrinsic oxidation potentials of common electrolyte solvents or anions obtained from DFT and higher level correlated methods were significantly higher than experimentally determined valnes from LSV experiments, especially when LSV measnrements were extrapolated to low scan rates [16, 34-36]. A step toward reconciling QC predictions and LSV measnrements was made in recent DFT stndies [16,34-36], which focused on the oxidation stability of solvent-anion and solvent-solvent clusters. These studies showed that the oxidation stabihty of solvent-solvent and solvent-anion clusters is lower than stability of the isolated solvents and anions that comprise these clusters. 

In order to connect the oxidation stability of the model electrolyte complexes to LSV experimental data, one needs to consider the reaction rates for the oxidation reaction of each complex. Indeed, the H-transfer reaction in the solvent-solvent or solvent-anion complexes leads to a significant molecular rearrangement and distortion thus, one expects a significant barrier for these oxidation reactions compared to the oxidation of an isolated EC. Rates for each electron transfer reaction can be estimated in a first approximation using Marcus theory of electron transfer, where the rate (k) of the activation-controlled reaction is proportional to 

10 mm in diameter [41]. Reprinted with permission from [41] Copyright 2001 Elsevier  

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