A method for preparing a positive electrode material for a rechargeable lithium battery, comprising the steps of: —providing a Li metal (M) oxide electroactive material, —providing an inorganic oxidizing chemical compound, —providing a chemical that is a Li-acceptor, —mixing the Li metal (M) oxide, the oxidizing compound and the Li-acceptor, and —heating the mixture at a temperature between 200 and 800° C. in an oxygen comprising atmosphere. In an embodiment the positive electrode material comprises a Li metal (M) oxide electroactive material, and between 0.15 and 5 wt % of a LiNaS04 secondary phase. The Li metal oxide may have the general formula Li1+a′M1−aO2, with a′