  An all solid-state thin film lithium ion battery has been touted the holy
grail for energy storage technology ever since the inception of the first one
in 1986 by Keiichi Kanehori. Solid-state batteries provide the distinct
advantage of outperforming current technology by having a simpler composition,
being easier and cheaper to manufacture, safer and having a higher theoretical
gravimetric and volumetric energy density. The commercialization of this
technology however, is plagued by its own set of challenges, primarily low
ionic conductivity and interfacial stability of the solid-state electrolyte
separating the anode and cathode, a small electrochemical window and sub-par
mechanical properties. In the last decade considerable progress has been made
in remedying these issues with garnet-type electrolytes, especially
Li7La3Zr2O12 (LLZO), having emerged the leading contender. This has prompted
renewed effects into the field of solid-state ionic's and maximizing the ionic
conductivity of LLZO by modifying its properties, primarily by means of doping
with a varying degree of success. Carving a clear road ahead requires an
in-depth understanding of the origin of the high Li+ ion conductivity, the
primary means of investigating which is by first-principle methods. In this
term paper we try to gain insight into the origin of mechanisms at play that
drive the collective migration of Li+ ions in LLZO using a first-principles
approach, to gain a deeper understanding and appreciation for optimizing its
properties for use in next-generation energy storage systems.
