Excellent electrochemical properties, Li ion dynamics and room temperature work function of Li2MnO3 cathode thin films

Abstract

We report on excellent electrochemical properties, Li ion diffusion coefficient and work function of Li2MnO3 thin films fabricated by RF sputtering technique. The x-ray diffraction study confirms the formation of Li2MnO3 thin film in layered structure. The x-ray photoelectron spectroscopy study confirms the existence of Li and Mn ions and their appropriate oxidation states in Li2MnO3 thin film. Work function of the Li2MnO3 thin film has been measured using scanning Kelvin probe microscopy and is found to be 5.51 eV. Electrochemical studies show that the Li2MnO3 thin film exhibits oxidation and reduction peaks at 2.98 V and 2.81 V respectively with the discharging capacity of 10 μAh cm−2 in the first cycle and 9 μAh cm−2 in the 100th cycle at a C rate of 25 μA cm−2. Electrochemical stability of Li2MnO3 thin film is probed by measuring the charge discharge profile with high sweep rate of 500 mV s−1. Li ion diffusion coefficient value is seen to 1.6 × 10−14 cm2 s−1 and 2.56 × 10−14 cm2 s−1 before and after the cycling respectively. Electrochemical studies indicate that Li2MnO3 thin films can be utilized as a promising cathode layer in all-solid thin film battery fabrication.