Smart construction of multifunctional Li1.5Al0.5Ge1.5(PO4)3|Li intermediate interfaces for solid-state batteries

Due to high ionic conductivity, low cost and excellent air stability, NASICON-type Li1.5Al0.5Ge1.5(PO)(4) (LAGP) electrolyte has been a promising candidate for high-performance solid-state batteries. Nevertheless, the poor interfacial compatibilities between LAGP and lithium (Li) metal (i.e., intrinsic instability of LAGP to metallic Li, growth of dendrite Li) retard its commercial application. Herein, a nano multifunctional LiF@Li-zinc (Zn) alloy layer consisting of electrically insulated but ionic conductive lithium fluoride (LiF) and Li-Zn alloy is introduced at the LAGP|Li interface (Z-LAGP) by in-situ conversion reactions. Such LiF@Li-Zn layer not only leads to stable and tight interface with low resistance and effective inhibition of side reactions, but also homogenizes the Li-ion flux with free of dendrite Li. Consequently, the Li|Z-LAGP|Li cells present the improved critical current density as high as 2.0 mA cm (-2), stable cycles with longer than 1000 h at 0.1 mA cm(- 2), and as well as superior cycling performance from 0.1 to 0.5 mA cm(-2) with stable overpotential. What is more, the solid-state batteries of Li|ZLAGP|LiFePO4 show the good cycle stability with highly reversible capacity ( > 150 mA h g(-1)) at 0.1 C under room temperature. This work highlights a rational design for the robust LAGP|Li interface and a novel strategy to optimizing interfacial compatibilities.

Automated summary

Due to its high ionic conductivity, low cost, and excellent air stability, the NASICON-type Li1.5Al0.5Ge1.5(PO)(4) (LAGP) electrolyte is considered a promising candidate for high-performance solid-state batteries. However, the poor interfacial compatibilities between LAGP and lithium metal hinder its commercial application. In this study, a nano multifunctional LiF@Li-zinc (Zn) alloy layer is introduced at the LAGP|Li interface to improve the interfacial stability and homogenize the Li-ion flux. This design leads to stable and tight interface with low resistance, effective inhibition of side reactions, and dendrite-free Li-ion flux.