Effect of Ni(2+) content on lithium/nickel disorder for Ni-rich cathode materials.

Li excess LiNi0.8Co0.1Mn0.1O2 was produced by sintering the Ni0.8Co0.1Mn0.1(OH)2 precursor with different amounts of a lithium source. X-ray photoelectron spectroscopy confirmed that a greater excess of Li(+) leads to an increase in the number of Ni(2+) ions. Interestingly, the level of Li(+)/Ni(2+) disordering decreases with an increase in Ni(2+) content determined by the I003/I104 ratio in the X-ray diffraction patterns. The electrochemical measurement shows that the cycling stability and rate capability improve with an increase in Ni(2+) content. After cycling, electrochemical impedance spectroscopy shows decreased charge transfer resistance, and the XRD patterns exhibit an increased I003/I104 ratio with an increase in Ni(2+) content, reflecting the decrease in the level of Li(+)/Ni(2+) disorder during cycling.