Atomic Layer Deposited Lithium Silicates as Solid-State Electrolytes for All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Fabricating solid-state electrolyte (SSE) thin films is crucial for developing all-solid-state batteries (ASSBs).
• Conventional deposition methods struggle to produce uniform and conformal SSE thin films with precise control.
• Atomic layer deposition (ALD) offers a promising alternative for controlled thin-film fabrication.

Purpose of the Study:

• To utilize atomic layer deposition (ALD) for fabricating lithium silicate thin films as potential solid-state electrolytes (SSEs) for all-solid-state batteries (ASSBs).
• To investigate the growth characteristics, composition, and ionic conductivity of ALD-deposited lithium silicate thin films.

Main Methods:

• Lithium silicate thin films were deposited using ALD by combining Li₂O and SiO₂ subcycles.
• Precursors included lithium tert-butoxide, tetraethylorthosilane, and H₂O.
• Characterization involved X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS).

Main Results:

• Uniform and self-limiting growth of lithium silicate thin films was achieved between 225 and 300 °C.
• XAS confirmed a SiO₄ tetrahedron structure with lithium oxide as a network modifier.
• XPS verified the chemical state of Li, and film composition was tunable by adjusting subcycle ratios.
• The thin film prepared at 250 °C showed an ionic conductivity of 1.45×10⁻⁶ S cm⁻¹ at 373 K.

Conclusions:

• ALD is an effective technique for depositing uniform lithium silicate SSE thin films.
• The ionic conductivity is attributed to high lithium concentration and low activation energy.
• These findings highlight the potential of ALD-grown lithium silicate for advanced ASSB applications.