Amorphous Lithium Lanthanum Titanate for Solid-State Microbatteries

Jungwoo Z Lee,Thomas A Wynn,Ying Shirley Meng,Huolin L Xin,Ziying Wang

doi:10.1149/2.0411701jes

Abstract

Lithium lanthanum titanate (LLTO) is a promising solid state electrolyte for solid state batteries due to its demonstrated high bulk ionic conductivity. However, crystalline LLTO has a relatively low grain boundary conductivity, limiting the overall material conductivity. In this work, we investigate amorphous LLTO (a-LLTO) thin films grown by pulsed laser deposition (PLD). By controlling the background pressure and temperature we are able to optimize the ionic conductivity to 3 × 10−4 S/cm and electronic conductivity to 5 × 10−11 S/cm. XRD, TEM, and STEM/EELS analysis confirm that the films are amorphous and indicate that oxygen background gas is necessary during the PLD process to decrease the oxygen vacancy concentration, decreasing the electrical conductivity. Amorphous LLTO is deposited onto high voltage LiNi0.5Mn1.5O4 (LNMO) spinel cathode thin films and cycled up to 4.8 V vs. Li showing excellent capacity retention. These results demonstrate that a-LLTO has the potential to be integrated into high voltage thin film batteries.

Highlights

FOCUS ISSUE OF SELECTED PAPERS FROM IMLB 2016 WITH INVITED PAPERS CELEBRATING 25 YEARS OF LITHIUM ION BATTERIES
These results demonstrate that a-LLTO is stable across the full voltage range and has minimal adverse interfacial reactions with LNMO
LLTO target characteristics.—X-ray diffraction (XRD) of the sintered ceramic pellet confirms that the target is highly crystalline and consists of the cubic perovskite phase mixed with the tetragonal phase (Fig. 1a)

Summary

Introduction

FOCUS ISSUE OF SELECTED PAPERS FROM IMLB 2016 WITH INVITED PAPERS CELEBRATING 25 YEARS OF LITHIUM ION BATTERIES. By controlling the background pressure and temperature we are able to grow films with high ionic conductivity (3 × 10−4 S/cm) several orders of magnitude higher than its electronic conductivity. Amorphous LLTO is deposited onto high voltage LiNi0.5Mn1.5O4 (LNMO) spinel thin films and cycled up to 4.8 V vs Li showing excellent capacity retention.

Results

Conclusion