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 degrees 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.