Ni-rich　layered　oxides　have　been　widely　applied　commercially　due　to　their　high　energy　density　and　capacity.　However,　there　are　still　some　drawbacks　of　capacity　fading,　O-2　release,　and　Li/Ni　exchange.　Cation　doping　has　been　proven　to　be　one　of　the　most　promising　strategies　to　improve　the　electrochemical　performances　of　Ni-rich　layered　oxides.　Herein,　density　functional　theory　(DFT)　calculations　have　been　performed　to　investigate　the　effects　of　doping　various　cations　(Sb5+,　Sn4+,　Ga3+,　Ge4+,　and　V5+)　on　the　structural　stability　and　electrochemical　performances　of　LiNi0.5Co0.2Mn0.3O2　(NCM523).　The　theoretical　results　show　that　Sb,　Sn,　Ga,　Ge,　and　V　doping　can　reduce　the　oxidation　state　of　Ni　ions.　Moreover,　doping　with　these　metals　can　inhibit　O-2　release　and　Li/Ni　exchange,　which　improves　the　safety,　capacity　retention,　and　rate　capacity.　Furthermore,　Ga　and　Ge　doping　can　improve　the　stability　of　partially　deintercalated　states,　suppress　lattice　distortion,　and　increase　the　intercalation　voltage.　In　conclusion,　Ga　and　Ge　doping　is　an　effective　strategy　to　optimize　the　electrochemical　performances　of　NCM523.