Low-cost　layered　oxides　free　of　Ni　and　Co　are　considered　to　be　the　most　promising　cathode　materials　for　future　sodium-ion　batteries.　Biphasic　Na0.78Cu0.27Zn0.06Mn0.67O2　obtained　via　superficial　atomic-scale　P3　intergrowth　with　P2　phase　induced　by　Zn　doping,　consisting　of　inexpensive　transition　metals,　is　a　promising　cathode　for　sodium-ion　batteries.　The　P3　phase　as　a　covering　layer　in　this　composite　shows　not　only　in　excellent　electrochemical　performance　but　also　its　tolerance　to　moisture.　The　results　indicate　that　partial　Zn　substitutes　can　effectively　control　biphase　formation　for　improving　the　structural/electrochemical　stability　as　well　as　the　ionic　diffusion　coefficient.　Based　on　in　situ　synchrotron　X-ray　diffraction　coupled　with　electron-energy-loss　spectroscopy,　a　possible　Cu2+/3+　redox　reaction　mechanism　has　now　been　revealed.