Due to well-known Jahn-Teller distortion in spinel LiMn1.5Ni0.5O4 it can only be reversibly electrochemically cycled between 3 and 4.8 V with a limited reversible capacity of similar to 147 mAh g(-1). This study intends to embed the layer-structured Li2MnO3 nanodomains into LiMn1.5Ni0.5O4 spinel matrix so that the Jahn-Teller distortion can be suppressed even when the average Mn oxidation state is below +3.5. A series of xLi(2)MnO(3).(1 - x)LiMn1.5Ni0.5O4 where x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and I are synthesized by coprecipitation method. The composites with intermediate values of x = 0.1, 0.2, 0.3, 0.4 and 0.5 exhibit both spinet and layered structural domains in the particles and show greatly improved cycle stability than that of the pure spinel. Among them, 0.3Li(2)MnO(3).0.7LiMn(1.5)Ni(0.5)O(4) delivers the highest and almost constant capacity after a few conditional cycles and shows superior cycle stability. Ex-situ X-ray diffraction results indicate that no Jahn-Teller distortion occurs during the cycling of the 0.3Li(2)MnO(3). 0.7LiMn(1.5)Ni(0.5)O(4) composite. Additionally, 03Li(2)MnO(3). 0.7LiMn(1.5)Ni(0.5)O(4) possesses a high energy density of similar to 700 Wh kg(-1), showing great promise for advanced high energy density lithium-ion batteries. (C) 2014 Elsevier B.V. All rights reserved.