The　Li-rich　cathode　materials　Li[CoxLi(1/3-x/3)Mn(2/3-2x/3)]O-2　with　different　Co　contents　(x=0.4,　0.5,　0.6)　were　synthesized　by　modified　Pechini　method.　The　results　of　XRD　confirmed　that　the　crystals　of　the　Li-rich　compounds　possess　layered　structure　and　have　good　crystallinity.　The　initial　discharge　capacities　of　the　compounds　are　high　between　200　similar　to　220　mAh/g,　increasing　with　the　increase　of　Co　contents.　The　material　with　x=0.4　exhibits　the　best　cycling　property.　The　capacity　retainment　is　about　75%　after　50　cycles　at　0.5　C　(100　mA/g).　The　peak　of　Mn4+/Mn3+　occurred　below　3.5　V　in　the　plots　of　dQ/dV,　and　the　area　of　the　peak　increases　with　the　cycle　numbers.　The　results　of　the　XRD　during　the　cycling　process　show　the　layer　structure　of　the　Li-rich　materials　transfers　to　the　spinel　phase,　and　the　impurities　appears　during　the　cycling,　resulting　in　the　capacity　fade.