Electrochemical and structural study on cycling performance of γ-LiV2O5 cathode

Electrochemical and structural properties of LiV2O5 cathode were investigated. Obtained by solid state reaction at high temperature the material crystallized as gamma polymorph phase, gamma-LiV2O5. The gamma structure provides two crystallographic sites to accommodate lithium ions, Li1 and Li2 position. Lithium insertion at these two sites occurs at two respective voltages versus lithium metal: -3.6 V (Li1) and -2.4 V (Li2). Intercalation at Li1 position is reversible in both organic and aqueous electrolyte and provides stable cycling performance at the high voltage. On the contrary, sluggish insertion/removal of Li+ at Li2 sites causes unstable performance and significant storage capacity fade at lower voltages. Lithium diffusion 3d landscape was determined by bond valence calculations applied on the gamma-LiV2O5 phase, as well as on the metastable phases of gamma '-V2O5 and zeta-Li2V2O5 that exist at high and low voltages respectively. The model was proposed based on inactivity of Li2 position of the metastable zeta-Li2V2O5 phase which provides explanation for the observed storage capacity loss at low voltages.

Automated summary

The electrochemical and structural properties of the LiV2O5 cathode were investigated, revealing differences in lithium ion insertion efficiency and stability at the Li1 and Li2 crystallographic sites, leading to different cycling performance at high and low voltages.