Capacity fading of spinel phase LiMn2O4 with cycling

The capacity fading with cycling between 3.5 V and 4.3 V of the spinel phas e 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 reacti on and the one-phase reaction, respectively. These reactions are also shown by the oxidation and reduction peaks in the cyclic voltammogram. As the nu mber 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 d estruction induced by strain causes the capacity fading of LiMn2O4 with cyc ling. The expansion and contraction of spinel phase LiMn2O4 due to the inte rcalation and deintercalation make the unit cell strained and distorted. Wi th cycling, the interstitial sites and thus the spinel structure will be de stroyed. This decreases the fraction of the spinel phase, leading to the ca pacity 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. (C) 1999 Elsevier Science S.A. All rights reserved.