Influence of the particle size on the electrochemical properties of lithium manganese oxide

LiMn2O4 powders with different particle sizes were obtained by sieving, and the influence of particle size on the electrochemical behavior was examine d. With a decrease in particle size, both the specific capacity and the cou lomb efficiency become markedly increased. It is suggested that the small p articles with large interface area provide more lithium ions for diffusion, leading to the high ionic current and specific capacity. The large interfa ce area between LiMn2O4 and the liquid electrolyte also increases the oppor tunity for lithium ions to intercalate back into the host structure. In the cyclic voltammetry test, small LiMn2O4 particles exhibit the oxidation pea ks at higher voltage during the deintercalation process. It is considered t hat the size of pores among LiMn2O4 particles is reduced when the particle size is decreased, and the reduced opening results in an increase in the ma ss-transfer resistance, therefore, more driving force is required to extrac t lithium ions from the cathode materials. (C) 2001 Elsevier Science B.V. A ll rights reserved.