Impact of synthesis method on phase transformations of layered Lithium Vanadium Oxide upon Electrochemical (De)lithiation

Li_1.1V₃O₈ (LVO) has shown promise as a cathode material for lithium-based batteries due to its high theoretical capacity (360mAh.g^-1) and good rate capability; however, LVO batteries suffer from capacity fade upon extended cycling. The impact of synthetic material control on electrochemistry and capacity retention was explored through solvothermal synthesis of LVO fibers and sol-gel synthesis of LVO rhombohedrons. Cyclic voltammetry (CV) of the twomaterials revealed key differences where lithiation of the solvothermal-derived LVO material resulted in less β phase formation as compared with the sol-gel-derived material. Structural evolution of the materials during lithiation was characterized through in situ XRD which revealed that the α→β phase conversion is essentially complete in the sol-gel product with only partial conversion in the solvothermal product. Under galvanostatic cycling, the sol-gel product delivered higher capacity but displayed more capacity fade as compared to the solvothermal product as foretold by both CV and XRD findings. When cycled within the αphase region, improved preservation of both energy delivery and structural integrity was observed. These findings substantiate the proposed cause of capacity degradation as originating from an α→β structural change and illustrate the possibility of minimizing β phase formation through synthetic control of LVO.