Unusual Conversion-type Lithiation in LiVO3 Electrode for Lithium-Ion Batteries

Abstract

This work finds that LiVO3 is lithiated by a conversion reaction at 25 °C, which is unusual for the family of vanadium oxides. The spectroscopic studies and first-principle calculations performed on the lithiation mechanism of LiVO3 consistently propose that a two-phase insertion-type lithiation proceeds in the early stage of lithiation; LiVO3 transforms into a rock-salt structured Li2VO3. The continuing single-phase Li+ insertion into the tetrahedral sites in the rock-salt Li2VO3 produces a more Li-rich phase (Li2.5VO3), which is highly distorted because of the unfavorable Li+ insertion into the tetrahedral sites such as to be vulnerable to lattice breakdown. Hence, a two-phase (nucleation/growth type) conversion reaction is followed along with a structural disintegration; the Li2.5VO3 phase decomposes into metallic vanadium and Li2O. To determine the factors facilitating the conversion reaction of LiVO3, galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EI...