Factor affecting the capacity retention of lithium-ion cells

Capacity failure due to the imbalance of coulombic efficiencies between positive and negative electrodes in a lithium-ion (shuttlecock) cell was examined by fabricating two types of cells, i.e., Li[Li1/3Ti5/3]O4/LiNiO2 and carbon/LiNiO2. Rechargeable capacity of a lithium-ion cell consisting of Li[Li1/3Ti5/3]O4 and LiNiO2 faded more rapidly than that of a cell based on natural graphite and LiNiO2 in spite of superior coulombic efficiency of Li[Li1/3Ti5/3]O4 (very close to 100%) compared with that of natural graphite (about 98%). The important role of the electrolyte upon the capacity retention of lithium-ion cells is described and specific problems to extend cycle life are discussed.