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 (MgF 2 ) film is successfully deposited onto each individual grain of an ultrahigh‐potential LiMn 1.5 Ni 0.5 O 4 ‐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.