Enhancement of Ultrahigh Rate Chargeability by Interfacial Nanodot BaTiO3 Treatment on LiCoO2 Cathode Thin Film Batteries

Nanodot BaTiO3 supported LiCoO2 cathode thin films can dramatically improve high-rate chargeability and cyclability. The prepared BaTiO3 nanodot is <3 nm in height and 35 nm in diameter, and its coverage is <5%. Supported by high dielectric constant materials on the surface of cathode materials, Li ion (Li+) can intercalate through robust Li paths around the triple-phase interface consisting of the dielectric, cathode, and electrolyte. The current concentration around the triple-phase interface is observed by the finite element method and is in good agreement with the experimental data. The interfacial resistance between the cathode and electrolyte with nanodot BaTiO3 is smaller than that without nanodot BaTiO3. The decomposition of the organic solvent electrolyte can prevent the fabrication of a solid electrolyte interface around the triple-phase interface. Li+ paths may be created at non solid electrolyte interface covered regions by the strong current concentration originating from high dielectric constant materials on the cathode. Robust Li+ paths lead to excellent chargeability and cyclability.