Enhancing electrochemical performance of thin film lithium ion battery via introducing tilted metal nanopillars as effective current collectors

Novel Li₂MnO₃ (LMO)-Au nanocomposite thin film with tilted Au pillars has been synthesized by using an oblique angle deposition technique (OAD) in pulsed laser deposition. The tilt angle and dimension of the Au nanopillars can be tuned by varying the inclination angle of the incoming flux and the growth rate. The obtained LMO-Au nanocomposite structure exhibits an initial volumetric discharge capacity of 35.78 μAh cm⁻² μm⁻¹ for the 1st cycle but increases to 62.32 μAh cm⁻² μm⁻¹ at the 100th cycle. Such an increase in discharge capacity upon cycling is attributed to significantly increased reaction depth upon cycling, indicating that Au pillars function as effective current collectors and the LMO-Au interfaces improve the cycling stability. In addition, the LMO-Au nanocomposites display highly anisotropic optical complex dielectric function in-plane and out-of-plane, reduced bandgap, and high hardness of 10 GPa which almost doubled that of pure Li₂MnO₃. This study presents a novel approach for processing nanocomposite thin films with tunable tilted current collectors towards advanced thin film battery cathode, nanoscale plasmonic systems, and other oxide-metal hybrid electrochemical systems.