Enhanced electrochemical properties of fluoride-coated LiCoO2 thin films
The electrochemical properties of fluoride-coated lithium cobalt oxide [LiCoO2] thin films were characterized. Aluminum fluoride [AlF3] and lanthanum fluoride [LaF3] coating layers were fabricated on a pristine LiCoO2 thin film by using a spin-coating process. The AlF3- and LaF3-coated films exhibited a higher rate capability, cyclic performance, and stability at high temperature than the pristine film. This indicates that the AlF3 and LaF3 layers effectively protected the surface of the pristine LiCoO2 film from the reactive electrolyte.
Atomic Layer Deposition of a Particularized Protective MgF2 Film on a Li-Ion Battery LiMn1.5Ni0.5O4 Cathode Powder Material
A several atomic layers thick magnesium fluoride (MgF2) film is successfully deposited onto each individual grain of an ultrahigh-potential LiMn1.5Ni0.5O4-powder material for Li-ion batteries. The resulting film has a marked protection action, as it does not compromise the cathode performance substantially, while it extends the cycle life of the cathodes prepared from the coated powder. The protective effect is pronounced at 45 °C and the catastrophic capacity fading is halted. The essence of the protecting action is suggested to be in blocking the access of aggressive electrolyte-decomposition byproducts to the cathode material surface.
HRTEM study of orthorhombic zirconia in MgO-PSZ
High-resolution transmission electron microscopy (HRTEM) was used to study the phase of orthorhombic ZrO2 formed in magnesia partially stabilized zirconia (MgO-PSZ) during HRTEM specimen preparation. Based on the three reported crystal structures of orthorhombic ZrO2, with the space groups Pbcm, Pbc21 and Pbca, here it is shown that orthorhombic ZrO2 formed in MgO-PSZ has the Pbcm structure.