The　Li-rich　cathode　material　Li1.2Co0.4Mn0.4O2(=0.5Li(2)MnO(3)center　dot　0.5LiCoO(2))　was　prepared　by　an　improved　molten　salt　method.　The　effects　of　sintering　temperature　and　time　on　the　physical　and　electrochemical　properties　of　Li1.2Co0.4Mn0.4O2　were　investigated.　With　increasing　sintering　temperature,　excellent　crystallinity　and　a　stable　structure　are　obtained,　which　lead　to　excellent　electrochemical　properties.　However,　the　sample　sintered　at　900　A　degrees　C　has　poor　performance　because　its　large　powder　diameter　prolongs　the　transportation　length　of　Li+　ions.　Higher　specific　surface　areas　are　obtained　when　samples　are　sintered　at　850　A　degrees　C　for　a　shorter　time,　which　leads　to　more　activity　and　excellent　charge/discharge　capacity.　The　evolution　of　a　derivative　peak　at　about　3.0　V　in　the　differential　capacity　(dQ/dV)　curves　is　observed　along　with　the　formation　of　a　spinel-like　phase,　which　is　verified　by　analysis　using　a　high-resolution　transmission　electron　microscope.　Therefore,　it　is　a　simple　and　quick　method　to　characterize　the　structure　evolution　upon　cycling　of　Li-rich　cathode　materials　by　means　of　analysis　of　the　derivative　peak.