Thermodynamic and Kinetic Properties of Materials for Next-Generation Rechargeable Batteries from First-Principles.

[摘要] To break out of small electronics and into vehicles, rechargeable battery technology needs to overcome several obstacles.First, safety issues plague the usage of liquid electrolytes in traditional Li-ion battery systems.Secondly, alternative elements to Li would be more earth-abundant as well as potentially have higher capacities.With these factors in mind, we will discuss thermodynamic and kinetic properties from first-principles calculations surrounding three next-generation materials for rechargeable batteries:a solid electrolyte, Li3OCl, for use in Li-ion batteries. a magnesium battery electrode (MgTiS2), and a sodium battery electrode (NaCoO2).First, we explore diffusion in Li3OX (X=Cl, Br), a superionic conductor with experimental conductivities on the order of 1 mS/cm. These compounds, which have an anti-perovskite crystal structure, have potential applications as solid electrolytes in Li-ion batteries to replace the currently-employed liquid electrolytes.We identify a low-barrier three-atom hop mechanism involving Li interstitial dumbbells. This hop mechanism is facile within the (001) crystallographic planes of the perovskite crystal structure and is evidence for the occurrence of concerted motion, similar to ionic transport in other solid electrolytes. Our first-principles analysis of phase stability predicts that antiperovskite Li3OCl (Li3OBr) is metastable relative to Li2O and LiCl (LiBr) at room temperature.Second, we examine the thermodynamic and kinetic properties of MgTiS2 and compare it to its well-known analog, LiTiS2 in order to better understand the difficulties obtaining facile diffusion in Mg-ion batteries.We show that although thermodynamically, the two systems are incredibly similar, the extra electron that Mg has over Li hinders diffusion immensely.Thirdly, we briefly investigate the spinel NaCoO2.Unlike any other spinel structure where intercalating species first occupy all tetrahedral sites then proceed to occupy octahedral sites, with sodium, both octahedral and tetrahedral sites are filled at various compositions leading to some unique thermodynamic and kinetic results.

[发布机构] University of Michigan

[效力级别] materials science

[关键词] first-principles calculations;materials science;rechargeable batteries;Materials Science and Engineering;Engineering;Science;Materials Science and Engineering