The high voltage application of the LiNi0.5Co0.2Mn0.3O2 cathode is still hindered by its unstable surficial structure and poor capacity retention. Surface coating has been proved to be an effective strategy to deal with these problems. However, previous multistep surface coating approaches greatly complicate the synthesis procedure. In this work, a simple and large-scale solid-state approach is developed to prepare lanthanum-based oxides co-coated LiNi0.5Co0.2Mn0.3O2 cathode materials. Electrochemical tests indicate that the co-coated samples exhibit superior cycle life and higher rate performance than those of the pristine sample. Further studies reveal that the enhanced interface stability and facilitated electron transportation can be attributed to the synergetic contribution provided by the lanthanum-based oxides co-coating layer. The present work demonstrates that our approach can achieve cathode synthesis and surface coating synchronously, and shows great potential to apply on a large scale and extent to all Ni-rich cathodes. •Lanthanum-based oxide co-coated LiNi0.5Co0.2Mn0.3O2 is prepared via a simple route.•The smart route achieves cathode synthesis and surface coating simultaneously.•The co-coated LiNi0.5Co0.2Mn0.3O2 shows superior electrochemical performance.•The co-coating layers enhance the de-lithiation kinetic and conductivity.•The co-coating layers suppress electrochemical degradation.