The Origin of Capacity Fading upon Lithium Cycling in Li1.1V3O8

Two Li 1 . 1 V 3 O 8 samples prepared by two different routes were investigated: SG350, obtained by firing a sol-gel precursor at 350°C, and SS580, obtained by solid-state reaction at 580°C. The electrochemical lithium insertion behaviors were studied and revealed important differences, especially on capacity fading upon lithium cycling. This article is focused on the lithium insertion mechanism in Li 1 . 1 V 3 O 8 and on its consequences on cyclability of the materials studied. This study shows that the capacity fading due to the two-phased phenomenon at 2.6 V could be related to an increase of the drastic change in cell lattice constants leading to local damage of the crystal structure. It seems also to depend on the morphology of the compound studied. The dissolution of small quantity of V I I I in the electrolyte may occur during the last electrochemical phenomenon at 2.35 V. It is also evidenced that this dissolution depends on the morphology of the compound studied. Discussions are provided on possible mechanisms for the dissolution process and on the relationships between the dissolution reaction and the capacity fading upon cycling.