Chemical and electrochemical interactions between positive electrode materials and electrolyte solutions and the evolution of the transport properties of subsequent products represent some of the most studied but still least understood lifetime determining phenomena occurring in batteries. This stems from a combination of characterization difficulty, inhomogeneity of products, and the real world deviation from ideal surfaces. The latter presents a further degree of challenge to theoretical modelling of such interactions. Despite the lack of a comprehensive understanding, experimental data from many groups over the past 20 years have consistently shown that the control of the positive electrode surface chemistry and the management of deleterious reactions through the chemistry of the electrolyte have resulted in truly extraordinary stabilization of the electrochemical performance. This talk will explore some of the relevant examples in contrasting electrochemical systems we have explored in our group and collaborators over the past two decades. The intent is to extract some of the common performance defining motifs and address some of the distinct differences observed. Examples from metal fluoride conversion, 4.7V LiNi0.5Mn1.5O4, and especially R-3m layered positive electrodes will be presented. Specific attention will be given to establishing the relative importance of addressing surface reactions vs. other failure modes.

A reflection on the performance defining properties induced by the positive electrode – Electrolyte interface chemistry

256th National Meeting (2018)

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