Work

Process-induced chemical reactions on interfaces of thin film ionic materials

Year: 2026

Type: article

Abstract: The success of ionic devices relies on the capability of miniaturizing them without compromising charge transport mechanisms and the optimum control of their interfacial properties, which remains as a challenge in this field. This study investigates autolithiation, wherein Li spontaneously transfers from growing dielectric layers (LiPON and Li 2 O) with similar thermodynamic stability but different reaction pathways into an underlying layered oxide film (V 2 O 5 ) commonly implemented in microbatteries and memory devices during magnetron sputtering. Electrochemical impedance combined with ellipsometry, X-ray photoelectron spectroscopy, and Raman spectroscopy reveal that interface reactions continue throughout deposition and post processing. LiPON forms stable, electron-blocking overlayers as thin as 15 nm while lithiating the underlying V 2 O 5 at rates equivalent to ∼1 μA/cm 2 . In contrast, Li 2 O deposition results in an overlayer growth of less than 2 nm with nearly complete Li transfer into the V 2 O 5 , achieving compositions approaching Li 3 V 2 O 5 . The results demonstrate that LiPON remains functional at nanoscale thicknesses despite concurrent autolithiation, while Li 2 O sputtering provides rapid lithium insertion with minimal overlayer formation, enabling rational design of thin film fabrication sequences for energy storage and neuromorphic devices.

Source: Solid State Ionics

DOI: 10.1016/j.ssi.2026.117271