High ionic conductivity and critical current density of Li7−xLa2.95Yb0.05Zr2−xTaxO12 solid electrolyte by modulation of Li+ distribution

Abstract

Safety concerns caused by organic liquid electrolyte in lithium battery might limit its application. Li7La3Zr2O12 is a promising electrolyte for solid-state lithium batteries due to its high ionic conductivity and interfacial stability with lithium. The influence of Ta doping on the structure, transport property and ionic conductivity of Li7−xLa2.95Yb0.05Zr2−xTaxO12 (0 ≤ x ≤ 0.2) has been investigated. Ta drives some Li ions from 24d to 96 h site and simultaneously optimizes the size of Li ion transport pathway. This structure modification increases the mobility, jump rate, and diffusion coefficient of lithium ion. Besides, the densification and grain contact have also been enhanced. The ionic conductivity of Li6.85La2.95Yb0.05Zr1.85Ta0.15O12 reaches 1.07 × 10−3 S cm−1 at 30 °C. The solid-state battery assembled with Li6.85La2.95Yb0.05Zr1.85Ta0.15O12 exhibits high critical current density of 1.1 mA cm−2 and discharge capacity of 166.7 mAh g−1, indicating that Li6.85La2.95Yb0.05Zr1.85Ta0.15O12 is a competitive solid electrolyte for solid-state lithium batteries.