Ceramic Li Ion Electrolytes for Next Generation Solid-State Li Ion Batteries

Abstract

At present, there is a growing interest in the development of safe and low-cost all-solid-state Li ion batteries for transport applications due to their higher practical volumetric and gravimetric energy densities compared to other known secondary batteries. The commercial Li ion battery utilizes LiPF6 dissolved organic polymer as an electrolyte, graphite anode and LiCoO2 electrode that exhibit several issues including safety, low energy density and inadequate chemical stability and durability. To this end, numerous solid-state Li ion electrolytes such as two-dimensional layered structures Li-beta alumina and Li3N, and three-dimensional structured Li4SiO4, Li2+2xZn1-xGeO4, Li1+xTi2−xAlxP3O12, (Li,Ln)TiO3 and Li5La3M2O12 (M = Nb, Ta) have been studied for all-solid-state Li ion batteries. Among these materials, garnet-like oxides have recently gained much attention because of their high Li ion conductivity, low electronic conductivity at high Li activity, and high electrochemical stability window, up to 6 V/Li. The lithium stuffing in the parent garnet-type Li5La3M2O12 increases Li ion conduction. For example, x = 0.75 members of Li5+2xLa3M2-xYxO12 show the highest Li ion conductivity of 10-4 Scm-1 at room temperature. In this talk, role of crystal chemistry on Li ion conductivity of the garnet-type solid Li ion electrolytes will be presented.