Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

23 September 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Non-crystalline Li+-ion solid electrolytes (SEs), such as lithium phosphorous oxynitride, can uniquely enable high-rate solid-state battery operation over thousands of cycles in thin film form. However, they are typically produced by expensive and low throughput vacuum deposition, limiting their wide application and study. Here, we report a non- crystalline SE of composition Li-Al-P-O (LAPO) with an ionic conductivity >10-7 S cm-1 at room temperature by spin coating from aqueous solutions and subsequent annealing in air. Homogenous, dense, flat layers can be synthesised with sub- micron thickness at temperatures as low as 230 °C. Control of the composition is shown to significantly affect the ionic con- ductivity, with increased Li and decreased P content being optimal, while higher annealing temperatures result in decreased ionic conductivity. Activation energy analysis reveals a Li+-ion hopping barrier of 0.42(1) eV. Additionally, these SEs exhibit low room temperature electronic conductivity (<10-11 S cm-1) and moderate Young’s modulus of ≈54 GPa, which may be beneficial in preventing Li dendrite formation. In contact with Li metal, LAPO is found to form a stable, but high impedance passivation layer comprised of Al metal, Li-P and Li-O species. These findings should be of value when engineering non- crystalline SEs for Li-metal batteries with high energy and power densities.

Supplementary materials

Title
Description
Actions
Title
Supporting Information
Description
Ionic conductivity comparison, XRD additional XPS and DRT analyses are provided.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.