LiNi0.5Co0.2Mn0.3O2powders　synthesised　via　a　citric　acid　assisted　sol-gel　method　were　subsequently　surface-modified　with　graphene　oxide　using　a　wet　chemical　method.　X-ray　diffraction　(XRD)　results　showed　that　the　graphene-oxide-coated　LiNi0.5Co0.2Mn0.3O2powders　exhibited　only　minor　differences　in　their　phase-structural　composition　compared　to　the　original　LiNi0.5Co0.2Mn0.3O2powders.　The　graphene-oxide-coated　LiNi0.5Co0.2Mn0.3O2sample　presented　a　core-shell　structure,　with　a　uniform　coating　layer　with　a　thickness　of　about　1　nm　discovered　on　the　surface,　as　confirmed　by　field　emission　scanning　electron　microscopy　(FE-SEM)　and　transmission　electron　microscopy　(TEM).　X-ray　photoelectron　spectroscopy　(XPS)　revealed　that　the　transition　metals　(M　=　Ni,　Co,　Mn)　maintained　a　high　oxidation　state　after　surface　modification　with　graphene　oxide.　The　cycle　performance　of　the　graphene-oxide-coated　LiNi0.5Co0.2Mn0.3O2was　significantly　enhanced　at　a　high　temperature　of　55　°C,　leading　to　a　capacity　retention　of　72%　after　100　cycles　compared　with　only　64%　for　the　bare　LiNi0.5Co0.2Mn0.3O2.　The　graphene-oxide-coated　LiNi0.5Co0.2Mn0.3O2also　demonstrated　better　performance　at　different　rates　than　the　pristine　sample.　The　effect　of　the　graphene　oxide　coating　layer　was　further　investigated　via　electrochemical　impedance　spectroscopy　(EIS),　which　indicated　that　this　layer　plays　an　important　role　in　stabilising　the　interface　between　electrolyte　and　cathode　during　cycling.　©　2017　Elsevier　B.V.