Investigating oxidative stability of lithium-ion battery electrolytes using synthetic charge-discharge profile voltammetry

Among the many properties which determine the applicability of a Li-ion battery electrolyte, electrochemical stability is a key parameter to consider. Despite being simple and straightforward to employ, the conventional linear sweep voltammetry (LSV) technique often leads to an over-estimation of oxidative stability. In this study, an alternative approach termed Synthetic Charge-discharge Profile Voltammetry (SCPV) is explored to investigate oxidative electrolyte stability. We have found this to be a convenient method of quantifying the anodic stability of the electrolyte in a more practically representative manner, in which passivation kinetics and electrode potential changes at the electrode-electrolyte interface are more appropriately reproduced. The viability of this technique is explored with liquid electrolytes based on ether, carbonate, sulfone and carbonate-sulfone mixtures, all with lithium hexafluorophosphate (LiPF6) salt, tested for a potential profile equivalent to LiNi0.5Mn1.5O4 electrodes. The credibility of this technique is validated by correlations to the coulombic efficiencies of corresponding half-cells.