Influence of lithium content on high rate cycleability of layered Li1+xNi0.30Co0.30Mn0.40O2 cathodes for high power lithium-ion batteries

Layered Li1+xNi0.30Co0.30Mn0.40O2 (x = 0, 0.05, 0.10, 0.15) materials have been synthesized using citric acid assisted sol–gel method. The materials with excess lithium showed distinct differences in the structure and the charge and discharge characteristics. The rate capability tests were performed and compared on Li1+xNi0.30Co0.30Mn0.40O2 (x = 0, 0.05, 0.10, 0.15) cathode materials. Among these materials, Li1.10Ni0.30Co0.30Mn0.40O2 cathode demonstrated higher discharge capacity than that of the other cathodes. Upon extended cycling at 1C and 8C, Li1.10Ni0.30Co0.30Mn0.40O2 showed better capacity retention when compared to other materials with different lithium content. Li1.10Ni0.30Co0.30Mn0.40O2 exhibited 93 and 90% capacity retention where as Li1.05Ni0.30Co0.30Mn0.40O2, Li1.15Ni0.30Co0.30Mn0.40O2, and Li1.00Ni0.30Co0.30Mn0.40O2 exhibited only 84, 71, and 63% (at 1C), and 79, 66 and 40% (at 10C) capacity retention, respectively, after 40 cycles. The enhanced high rate cycleability of Li1.10Ni0.30Co0.30Mn0.40O2 cathode is attributed to the improved structural stability due to the formation of appropriate amount of Li2MnO3-like domains in the transition metal layer and decreased Li/Ni disorder (i.e., Ni content in the Li layer).