A method of forming a metal oxy-fluoride surface on lithium metal oxide cathode material particles is disclosed. Such a metal oxy-fluoride surface may help to prevent lithium metal oxide cathode active materials from reacting with water, thus enabling aqueous processing of cathodes made from such materials in the manufacture of lithium batteries. Such a method may also reduce lithium battery manufacturing costs and time by substituting water for currently-used organic solvents that are expensive and require special handling and disposal. Such a method may also reduce the cost of lithium metal oxide cathode active materials as the requirements for moisture-free manufacture, storage, and processing will be reduced or eliminated.