Investigation of Zn Doped Li_1.5Al_0.5−xZn_xGe_1.5(PO₄)₃ (x = 0, 0.1 & 0.2) as a Solid Electrolyte for Li Ion Batteries

Abstract

All solid lithium-ion batteries (ASLB) have gained a lot of attention as it could deliver high energy and power density. In order to completely establish ASLB, proper understanding of solid electrolyte is very vital and the research from diverse point is still undergoing. Among them, NASICON-type phosphate based solid electrolytes are one of the promising materials due to good ionic conductivity and atmospheric stability. Addition of proper dopants into the parent material could cause an increment in their ionic conductivity as well as stability, thus fitting the material apt as solid electrolyte. This study aims in understanding the effect of ionic conductivity and stability of Lithium Aluminium Germanium Phosphate (LAGP) material upon adding Zinc as dopant material. We explored the effect of structural, ionic conductivity, stability against Li and Ac conductivity properties of Li1.5Al0.5−xZnxGe1.5(PO4)3 solid electrolyte with x = 0, 0.1 and 0.2. Our study showed that doping of aluminium with slightly bigger Zn ion could enhance the stability and conductivity of the material without changing the crystal structure. When x = 0.1 the ionic conductivity of the material attained is 1 × 10−5 S cm−1 at RT, which reaches 2.57 × 10−5 S cm−1 at 60 °C. Such a change in conductivity arises due to the expansion of ionic pathways which can be further tuned by exploring the limiting concentration 0 ≤ x < 0.1. Moreover, the sample also showed good stability at 0.03 and 0.05 mA cm−2 current densities against Li metal. Present study shows that Zn doping can improve the ionic conductivity of LAGP moderately and it can be used as a solid electrolyte for fabricating all-solid-state batteries.