Abstract:
 
Reversible electrochemical conversion reactions, although promising from fundamental energy perspectives, face challenges related to reversibility and cycle life. The energy inefficiencies associated with hysteresis in the reaction potential and capacity loss during long term cycling, limit the advancement of high-capacity conversion batteries towards commercial applications. During conversion, both atomic structure and nano structure of the electrode undergo continuous, complex and dynamic changes increasing the number of potential processes that can degrade reversibility, reduce cycle life and contribute to failure. Identifying correlations in electrochemical performance to the atomic and electronic constituents is a significant characterization challenge magnified by the nanoscale nature and chemical heterogeneity of the electrode and reaction products. Using pair distribution function analysis of high energy X-ray data and small angle scattering measurements applied operando, during electrochemical cycling, we identify the origins of limitations in these multiphase reactions governing energy storage in these complex materials.