Dual Influence of Li Concentration and Nanoparticle Size in LiCoO2 on the Conductivity and Storage Capacity of Lithium Batteries

LixCo1−xO2 nanocomposites with molar concentrations x (0.1, 0.3, 0.5, 0.7, 0.9) were prepared using the sol–gel method. The optical and electrical properties were determined using UV-Vis spectrometer. The results obtained indicate that the absorption coefficient increases upon increase of nanoparticle size, while the energy gap decreases when nanoparticle size increases. The storage capacity reaches its maximum value near resonance at minimum nanoparticle size. This is attributed to the fact that the optical properties, electrical conductivity, and actual electrical permittivity reach their maximum values near the resonance region and increase as the nanoparticle size decreases. The operating voltages at which the storage capacity attains maximum value in the range from 2.3 to 3.5 volts. These operating voltages can be adjusted to achieve the required range by controlling the Li concentrations and the crystallite size of LixCo1−xO2 NPs which directly affect the energy gap and, in turn, influence the operating voltage. The operating voltage can thus be increased by increasing the energy gap, which requires decreasing the nano size and the Li concentration.