Lithium ion batteries (LIBs) have been considered as promising energy storage devices in the past decades owing to their high operating voltage, large energy density and outstanding cycle performance. However, the currently commercial LIBs could not fulfill the demand of electric vehicles(EV) or hybrid electric vehicles(HEV) applications. Thence, superior electrode materials possessing either higher capacity or higher voltage have gained enormous interest. Taking this into account, spinel LiNi_0.5Mn_1.5O₄ which owns high operating voltage, relatively high theoretical capacity (147 mAh ·g^-1) and three-dimensional lithium ion transport channels has become one of the most excellent cathode materials. In the presented paper, the structure and synthesis of this material are reviewed, and special emphases are shown to the current research activities on LiNi_0.5Mn_1.5O₄ cathodes in ion doping along with surface coating synthesized by various synthetic techniques. Finally, the key issues and prospects of the cathode material are commented.

Contents
1 Introduction
2 Structure of LiNi_0.5Mn_1.5O₄ cathode material
3 Synthesis of LiNi_0.5Mn_1.5O₄ cathode material
4 Problems of LiNi_0.5Mn_1.5O₄ cathode material
5 Modification of LiNi_0.5Mn_1.5O₄ cathode material
5.1 Ion doping
5.2 Surface modification
5.3 Other methods
6 Conclusions and outlook