Atomic Layer Deposition of Lithium Tantalum Oxide Solid State Electrolyte Deposited Over Zirconium Oxide Protected Lithium Discs
Abstract
We report the successful deposition of a lithium-tantalum oxide (LixTayOz) solid-state electrolyte on ZrO2-coated lithium discs using Plasma Enhanced Atomic Layer Deposition (PEALD). ZrO2 layers deposited on lithium discs successfully increased the lithium substrates thermal stability, allowing the deposition temperature of the lithium tantalum oxide layer to be increased to 175 deg C. A pulsing sequence of 1 x Li2O + 6 x Ta2O5 was used for the deposition process. The effects of different tantalum ethoxide (TaEO) pulse durations on the deposited lithium tantalumoxide film were also studied. The deposited solid-state electrolyte layer was characterized using SEM, XPS, AFM, and four-point probe conductivity. From this characterization, we confirmed the successful uniform deposition of a lithium tantalum oxide solid-state electrolyte. The deposition rate of the solid-state electrolyte averaged 6.3 A per cycle as measured by AFM. The resistivity of the lithium tantalum film was 2.0 kOmega per square, which indicates that the solid-state electrolyte is electronically insulating and could help prevent energy leakage and side reactions in the battery. We observed two types of chemical binding energy within the lithium tantalum film: Li-O-Ta and Ta-O-Ta. The ratio of the two binding types is closely related to the TaEO pulse duration and the number of Ta2O5 subcycles. The composition of lithium tantalum oxide film, LixTayOz, can also be tuned by the number of Ta2O5 subcycles. We also found that Ta2O5 can prevent Li2O on the surface of the lithium tantalum oxide electrolyte layer from reacting with ambient CO2. Therefore, Ta2O5 can be used to increase the stability of the lithium tantalum oxide film. However, excess Ta in the lithium tantalum oxide film will reduce the Li+ conductivity of the deposited layer, which is detrimental to solid-state electrolyte applications.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2021
- Accession Number
- AD1146695
Entities
People
- Bo Yin
- Jeffrey R. Alston
Organizations
- North Carolina Agricultural and Technical State University