LiNi0.5Co0.2Mn0.3O2　cathode　material　synthesized　by　a　sol-gel　method　was　surface-modified　by　double-layer　coating.　The　results　of　X-ray　diffraction　(XRD)　confirm　that　the　intrinsic　structure　was　no　change　after　surface　modification.　A　double-layer　structure　consisting　of　an　inner　V2O5　(VO)　layer　and　an　outer　conductive　graphene　oxide　(GO)　layer　was　coated　on　the　surface　of　active　material,　as　confirmed　by　transmission　electron　microscopy　(TEM).　The　results　of　field　emission　scanning　electron　microscope　(FESEM)　equipped　with　an　energy　dispersive　spectroscope　(EDS)　show　that　both　graphene　oxide　and　V2O5　uniformly　covered　LiNi0.5Co0.2Mn0.3O2　cathode　material.　The　double-layer-coated　LiNi0.5Co0.2Mn0.3O2　cathode　material　shows　improved　electrochemical　performance　with　a　capacity　retention　of　74.2%　after　50　cycles　in　a　range　of　2.5-4.5　V　at　55　degrees　C,　compared　with　only　67.8%　capacity　retention　for　the　pristine　material.　In　addition,　the　double-layer-coated　LiNi0.5Co0.2Mn0.3O2　releases　116.6　mAh　g(-1)　under　a　high　current　rate,　while　the　pristine　material　only　remains　at　105.7　mAh　g(-1).　The　results　can　be　ascribed　to　the　double　coating　layer　not　only　avoids　the　side　reaction　between　electrolyte　and　active　material　but　also　promotes　Li+　and　electronic　conductivity.　Differential　capacity　(dQ/dV)　and　electrochemical　impedance　spectroscopy　(EIS)　measurements　reveal　that　the　double　coating　layer　effectively　suppresses　the　increase　of　the　electrode　polarization　during　cycling.　(C)　2017　Elsevier　B.V.　All　rights　reserved.