K,Na-Vanadium Oxide Compounds for Lithium-Ion Batteries: Synthesis and Electrochemical Performance in a Redox Reaction with Lithium

Heterogeneous vanadium oxide compounds (bronzes and vanadates) attract designers of lithium-ion batteries due to their superior structural integrity in a redox reaction with lithium compared to V2O5, a standard intercalation electrode material for lithium-ion batteries. The structural stability favors improved discharge behavior of lithium-ion batteries based on potassium- and sodium-containing vanadium oxide compounds. We investigate the effect that the copresence of potassium and sodium ions has on the electrochemical transformation of vanadium oxide compounds in electrodes for rechargeable lithium-ion batteries. Results of X-ray diffraction analysis suggest that dispersed precipitates deposited at the anode depend on the electrolyte composition. The precipitates containing the vanadates Na5V12O32 and KV5O13 are formed in potassium metavanadate solutions containing sodium ions, and the vanadates Na10V24O64 and KV5O13 are formed in vanadyl sulfate solutions containing potassium and sodium ions. The evaluation of electrochemical behavior of the synthesized material suggests that it has potential for use in lithium-ion batteries. The vanadates prepared in vanadyl sulfate solutions and incorporated in thin-layer matrix-free electrodes of a lithium battery display superior cycling efficiency compared to V2O5. Implementations of thin-layer lithium batteries based on the Na,K-vanadium oxide compound synthesized in vanadyl sulfate solution may benefit from the positive effect resulting from the copresence of potassium and sodium.

Automated summary

This study investigates the effect of potassium and sodium ions on the electrochemical transformation of vanadium oxide compounds in electrodes for rechargeable lithium-ion batteries. The results suggest that the synthesized material has potential for use in lithium-ion batteries, especially in thin-film lithium batteries displaying superior cycling efficiency.