Structural and electrochemical properties of gamma LiV2O5 cathode

Abstract

For its capability to reversibly remove and insert lithium ions in the range of 0 ≤ x ≤ 1.4, gamma polymorph phase of LixV2O5 makes a solid candidate for cathode application in rechargeable batteries. Accommodation of lithium in concentrations higher than x ≈1.4 brings stability issues related to the transformation towards the metastable ζ phase, which significantly limits utilization of higher capacities the material could achieve. The presented investigation has been conducted on γ-LiV2O5 powder obtained via solid state reaction at high temperatures. Structural refinement of the prepared γ phase has been carried out. Based on bond valence analysis of γ as well as of metastable γ’ and ζ phase, which occur at low and high lithium concentrations, respectively, mechanism is proposed for the observed capacity decrease. Electrochemical characteristics of γ-LiV2O5 were investigated in both aqueous and organic electrolyte in the voltage range 4-2.3 V vs. Li+/Li in order to record performances of all three occurring phases, γ and both lithium poor γ’ (high voltage region) and lithium rich ζ (low voltage region). Ionic exchange of Li+ with Mg2+, Ca2+ and Al3+ in their respective aqueous electrolytes has been conducted to examine potential use of the material in the postlithium rechargeable batteries.