Comparative Electrochemical Study of Li⁺, Na⁺ and Mg²⁺-ion Insertion into VO<inf>2</inf>(B) from Aqueous Nitrate Solutions

Abstract

The insertion of Li+, Na+ and Mg2+ into nanostructured VO2(B) from aqueous nitrate solutions was sudied by using cyclic voltammetry (CV) and galvanostaic (GS) cycling. CV experiments demonstrated fast and very stable insertion/deinsertion process of all three ions at scan rates 10-50 mV·s−1, but showed that extraction of Na+ and Mg2+ ion happens in wider voltage range and is more complex. GS cycling of nanostructured VO2(B), at current rates 200, 500 and 1000 mA·g−1, showed fairly large capacity values for all cations, with the highest Coulombic efficiency at the highest current rate. The GS cycling confirmed the two-step extraction of Mg2+-ions, while in the case of Na+-ions the extraction occurred more like a one step process.