Li2MnO3 Thin Films with Tilted Domain Structure as Cathode for Li-Ion Batteries

Abstract

Li2MnO3 thin film cathodes with tilted domain morphology have been synthesized by a simple one-step oblique-angle deposition (OAD) method using pulsed laser deposition. The cathode thin films with tilted domains show significantly improved kinetics than the conventional planar form of Li2MnO3 thin film, which is attributed to the facilitated Li-ion intercalation paths in the tilted domains. The OAD grown Li2MnO3 decreases the cathode–electrolyte interphase thickness as evidenced by transmission electron microscopy and X-ray photoelectron spectrometry data. The cathode with the tilted domains in the coin cell battery can be continuously cycled for 100 times, while the conventional planar Li2MnO3 failed after nine cycles. In the electrochemical window of 2.0–4.8 V, the tilted Li2MnO3 demonstrates first cycle capacity of 99.5 μAh cm–2 μm–1 with about 80% capacity retention after 100 cycles. This demonstration on morphology tuning in thin film cathode suggests enormous potential in thin film cathode designs toward future high efficiency thin film Li-ion batteries.