Li-rich 3d-transition metal layered oxides xLi2MnO3·(1 − x)LiMO2, one of the increasingly prospective cathode materials for high energy–density lithium-ion batteries, have attracted intensive attention by the research community. Nevertheless, their practical commercial applications are hindered by problems like the drop in the capacity and discharge voltage during cycling. Here, Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 is synthesized by sol–gel process. The outstanding electrochemical performance of which is benefited from its layered-spinel heterostructure which composited by amounts of spinel LiNi0.5Mn1.5O4. The results indicate that spinel LiNi0.5Mn1.5O4 can inhibit phase transformation as well as facilitate fast lithium-ion transportation. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.