Keywords: sol-gel process, bilayered vanadium oxide, intercalation, electrode materials, batteries
Summary:Continuously growing demand for energy storage stimulates research into new electrochemical systems, such as intercalation based beyond lithium-ion (BLI) batteries. Affordability of such batteries, compared to lithium-ion batteries, is related to the higher abundance and therefore lower cost of sodium, magnesium and other BLIs with respect to lithium. However, these ions are heavier and either larger (Na+ or K+ ions) or more highly charged (Mg2+ or Al3+ ions), which leads to slow diffusion and deterioration of battery performance parameters, such as capacity, power density and electrochemical stability over extended cycling. Therefore, development of the methods for improving diffusion of the beyond lithium charge carrying ions is essential for creating next generation energy storage systems with high performance. In this work, we present a new materials synthesis method that allows insertion of inorganic ions into the crystal structure of battery electrode material using soft chemistry approach, prior to the electrochemical cycling. We use vanadium oxide as high capacity host electrode material. We will discuss the importance of synthesis parameters for the formation of bilayered V2O5, a unique crystallographic form of vanadium oxide with exceptionally large interlayer distance (~10 – 13 Å) that favors diffusion of the charge carrying ions. Using a chemical pre-intercalation technique developed in our laboratory, we have synthesized Li-, Na-, K-, Mg-, and Ca-stabilized bilayered V2O5. We will demonstrate the record high specific capacity of Na-preintercalated V2O5 in Na-ion batteries and discuss strategies for the improvement of capacity retention based on post-synthesis treatment and pillaring of the bilayered V2O5. Our method can be used for the chemical pre-intercalation of a wide variety of alkali and alkali-earth metal ions, opening an opportunity to create efficient battery electrodes for various intercalation based BLI batteries.