The role of grain boundaries in solid-state Li-metal batteries

Abstract

Despite the potential advantages promised by solid-state batteries, the success of solid-state electrolytes has not yet been fully realised. This is due in part to the lower ionic conductivity of solid electrolytes. In many solid superionic conductors, grain boundaries are found to be ionically resistive and hence contribute to this lower ionic conductivity. Additionally, in spite of the hope that solid electrolytes would inhibit lithium filaments, in most scenarios their growth is still observed, and in some polycrystalline systems this is suggested to occur along grain boundaries. It is apparent that grain boundaries affect the performance of solid-state electrolytes, however a deeper understanding is lacking. In this perspective, the current theories relating to grain boundaries in solid-state electrolytes are explored, as well as addressing some of the challenges which arise when trying to investigate their role. Glasses are presented as a possible solution to reduce the effect of grain boundaries in electrolytes. Future research directions are suggested which will aid in both understanding the role of grain boundaries, and diminishing their contribution in cases where they are detrimental.

On the Origin of the Non‐Arrhenius Na‐ion Conductivity in Na3OBr

“…The importance of non-bulk factors in determining the overall ionic conductivity of solid electrolytes has been previously investigated, with the majority of work focusing on the effect of grain boundaries. [30,[39][40][41][42][43] However, the…”

Computational Design of Antiperovskite Solid Electrolytes

“…We first consider GBs, which are defined as surfaces of contact between differently orientated crystallites that often display different structural and composition features when compared to the bulk crystal . GBs can significantly influence the overall conductivity of a material, either positively or detrimentally. ,− Despite the fact that GBs are known to significantly impact the overall kinetics of ion transport, their pertinent properties and influence are still not fully understood, especially when compared to those of bulk materials.…”

Quantitative Mapping of Chemical Defects at Charged Grain Boundaries in a Ferroelectric Oxide

“…[ 4 ] Furthermore, grain boundaries play a crucial role for the fundamental physical characteristics of polycrystalline materials and co‐determine, for instance, their thermal and electronic conductivities. Understanding their unique local properties is essential for optimizing the functional properties of polycrystals, enabling the improvement of varistors [ 5 ] and solid electrolytes, [ 6 ] and material systems for caloric cooling [ 7 ] and next‐generation capacitors. [ 8 ] In many cases, the newly formed properties are attributed to, or go hand in hand with, an accumulation (or depletion) of point defects.…”