中性子を利用したLi₂S-P₂S₅系リチウムイオン伝導体の構造およびイオン伝導経路の可視化

抄録

Designing the next generation of lithium ion batteries （LIBs） requires fundamental information that surprisingly often is still unknown-for example, details of how ions actually move through a working device. Li₇P₃S₁₁ crystal and （Li₂S）x（P₂S₅）_100－x glasses have received a great deal of attention as a solid electrolyte for all-solid-state LIBs because of its extremely high ionic conductivity of 10^－4 to 10^－2 S/cm at room temperature. The authors predict and visualize the conduction pathways of Li ions in Li₇P₃S₁₁ crystal and （Li₂S）x（P₂S₅）_100－x glasses, using reverse Monte Carlo （RMC） modeling and the bond valence sum （BVS） approach with neutron diffraction data. The conduction pathways of Li ions can be classified into two types: relatively “stable” regions and “metastable” regions for Li ions. Furthermore, the authors use quasielastic neutron scattering to directly monitor the fast diffusion of Li ions in Li₇P₃S₁₁ crystal. According to the jump diffusion model, Li ions migrate between stable regions within a jump length ＜l＞＝4.3 Å along conduction pathways.