Li4-xGe1-xPxO4 a potential solid-state electrolyte for all-oxide microbatteries

TL;DR

This study explores Li4-xGe1-xPxO4 as a promising solid-state electrolyte for all-oxide microbatteries, demonstrating its potential through experimental thin film deposition and first-principles simulations of lithium ion conductivity.

Contribution

It introduces Li4-xGe1-xPxO4 as a novel electrolyte material with favorable properties for microbatteries, combining experimental and computational analysis.

Findings

Thin films can be fully crystalline or amorphous depending on deposition temperature.

Conductivity is stable despite grain boundaries, air exposure, or lithium deficiencies.

Simulations estimate a maximum conductivity of 10^-2 S/cm at 300°C.

Abstract

Solid-state electrolytes for Li-ion batteries are attracting growing interest as they allow building safer batteries, also using lithium metal anodes. Here we studied a compound in the lithium superionic conductor (LISICON) family, i.e. Li4-xGe1-xPxO4 (LGPO). Thin films were deposited via pulsed laser deposition and their electrical properties were compared with ceramic pellets. A detailed characterization of the micro structure shows that thin films can be deposited fully crystalline at higher temperatures but also partially amorphous at room temperature. The conductivity is not strongly influenced by the presence of grain boundaries, exposure to air or lithium deficiencies. First-principles molecular dynamics simulations were employed to calculate the lithium ion diffusion profile and the conductivity at various temperatures of the ideal LGPO crystal. Simulations gives the upper limit of conductivity for a defect free crystal, which is in the range of 10-2 S cm-1 at 300 deg. The ease of thin film fabrication, the room-temperature Li-ion conductivity in the range of a few microS cm-1 make LGPO a very appealing electrolyte material for thin film all-solid-state all-oxide microbatteries.