Enhanced Electrochemical Performance in Ni-Doped LiMn2 O4-Based Composite Cathodes for Lithium-Ion Batteries

High-voltage and high-performance Ni-doped LiMn2O4-basedcomposite cathodes have been obtained from the nominal formula of Li2Mn1-xNixSiO4, synthesized by using a citric acidassisted sol-gel method. The spinel Li(Mn, Ni)(2)O-4 and layered Li-2 SiO3 coexist in the composites with x= 0 and 0.05, whereas the materials with x= 0.15 and 0.25 consist of Li(Mn, Ni)(2)O-4, Li-2 SiO3 and layered LiNiO2; at x >= 0.35, the impurity phases of NiO and Ni6MnO8 are detected. A significant improvement in discharge capacity and rate performance of the materials has been caused by the simultaneous existence of LiNiO2 and Li2SiO3. The composite with x= 0.25 givesa very high initial discharge capacity of 168 mAhg(-1) in the potential range of 3-5 V and exhibits an excellent rate performance. Our study shows that the composites consisting of Li(Mn, Ni)(2)O-4, Li-2 SiO3, and LiNiO(2)w may be promising candidates for high-voltage and high-performance lithium-ion batteries.