Synthesis and Electrochemical Behavior in Redox Reaction with Lithium of K,Na (V-Oxide Compounds)

Abstract

UDC 544.643-621.357

DOI https://doi.org/10.5281/zenodo.4455852

Heterogeneous vanadium-oxide compounds (bronzes, vanadates) attract the attention of developers of lithium batteries due to an increased structural stability of those oxides in the redox reaction with lithium as compared with the resistance of V₂O₅ oxide, a traditional intercalation electrode material for Li-batteries. Structural stabilization improves the discharge characteristics of Li-batteries based on potassium-containing and sodium-containing vanadium oxide compounds. In this work, the combined effect of potassium and sodium ions on the electrochemical transformation of vanadium oxide compounds in electrodes for usage in a Li-battery was investigated. According to the data of the X-ray phase analysis, dispersed deposits were obtained at the anode, depending on the composition of the electrolyte. From the solutions of potassium metavanadate in the presence of sodium ions, the deposits contain Na₅V₁₂O₃₂ and KV₅O₁₃ vanadates; from the solutions of vanadyl sulfate in the presence of potassium and sodium ions, vanadates Na₁₀V₂₄O₆₄ and KV₅O₁₃ are formed. The evaluation of the electrochemical parameters of the synthesized material indicates the possibility of its use in Li-batteries. The cycling efficiency of vanadates obtained from vanadyl sulfate solutions in thin-layer ballastless electrodes of a lithium battery exceeds that of V₂O₅ oxide. The positive combined potassium-sodium effect can be useful for the implementation of thin-layer lithium batteries based on electrochemically synthesized K,Na (V-oxide compounds) obtained from a solution of vanadyl sulfate.

Keywords: lithium battery, K,Na-vanadates, electrochemical synthesis, discharge capacity, metavanadate and vanadyl sulfate electrolytes.