Enhanced Electrochemical Performance in Ni-Doped LiMn₂O₄-Based Composite Cathodes for Lithium-Ion Batteries

KGaA, Weinheim 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 acid-assisted sol-gel method. The spinel Li(Mn,Ni)2O4and layered Li2SiO3coexist in the composites with x=0 and 0.05, whereas the materials with x=0.15 and 0.25 consist of Li(Mn,Ni)2O4, Li2SiO3and layered LiNiO2; at x≥ 0.35, the impurity phases of NiO and Ni6MnO8are detected. A significant improvement in discharge capacity and rate performance of the materials has been caused by the simultaneous existence of LiNiO2and Li2SiO3. The composite with x=0.25 givesa very high initial discharge capacity of 168 mAh g−1in the potential range of 3–5 V and exhibits an excellent rate performance. Our study shows that the composites consisting of Li(Mn,Ni)2O4, Li2SiO3, and LiNiO2may be promising candidates for high-voltage and high-performance lithium-ion batteries.