Vanadium oxide–propylene carbonate composite as a host for the intercalation of polyvalent cations

A vanadium oxide/propylene carbonate nanocomposite has been synthesized by the sol–gel method using vanadium alkoxide as a precursor. The resulting bicontinuous structure consisted of mesopores filled with PC molecules and a network of hydrated vanadium oxide. The structure, engineered for the insertion of polyvalent cations, resulted in a specific capacity as high as 465 mAh per gram of vanadium oxide when Ca2+ was the guest cation. This is close to 80% of the theoretical capacity for 2e− per V. The critical role of the PC has been clearly demonstrated. The specific capacity of the nanocomposite when Ca2+ was used as the guest cation was two to ten times better when the propylene carbonate or its decomposition products was present in the structure as opposed to when it was either not added or extracted. It has also been shown that the nanocomposite exhibited better electrochemical performances with Ca2+ as the guest cation than with Li+.