Capacity fading of spinel phase LiMn2O4 with cycling

Abstract

Abstract The capacity fading with cycling between 3.5 V and 4.3 V of the spinel phase LiMn2O4 reveals the decrease in the lengths of two voltage plateaus at 4.15 V and 4.0 V in the V vs. x curves, corresponding to the two-phase reaction and the one-phase reaction, respectively. These reactions are also shown by the oxidation and reduction peaks in the cyclic voltammogram. As the number of cycle increases, the regions of the two-phase reaction and the one-phase reaction in the V vs. x curves decrease simultaneously. The lattice destruction induced by strain causes the capacity fading of LiMn2O4 with cycling. The expansion and contraction of spinel phase LiMn2O4 due to the intercalation and deintercalation make the unit cell strained and distorted. With cycling, the interstitial sites and thus the spinel structure will be destroyed. This decreases the fraction of the spinel phase, leading to the capacity fading of LiMn2O4 with cycling. Vacancy of interstitial sites by the deintercalation of Li ions and the attraction of oxygen with the remaining Li ions make shorter the lattice parameters of the cubic structure phases as the deintercalation proceeds.