Rational design of layered oxide materials for sodium-ion batteries

TLDR

Layered metal oxides, such as lithium cobalt oxide, are key for rechargeable batteries, but in sodium cells both octahedral and trigonal prismatic structures can form, and how to predict and control these structures remains unclear. The authors predict sodium coordination by weighting ion charge and radius with stoichiometry to decide if interlayer sodium stays octahedral or becomes trigonal prismatic. Zhao et al., Science, p.

Abstract

Layering the charge Layered metal oxides such as lithium cobalt oxide have attracted great attention for rechargeable batteries. In lithium cells, only the octahedral structure forms, but in sodium cells, trigonal prismatic structures are also possible. However, there is a lack of understanding about how to predict and control the formation of each structure. Zhao et al. used the simple properties of ions, namely their charge and their radius appropriately weighted by stoichiometry, to determine whether sodium in the interlayers between the transition metal or other ion-oxide layers remain octahedral rather than switching over to trigonal prismatic coordination. Science , this issue p. 708