Exploration of vanadium benzenedicarboxylate as a cathode for rechargeable lithium batteries.

The electrochemical reaction with lithium of a vanadium-based metal-organic framework V IV (O)(bdc) [MIL-47], which is isostructural to the iron compound MIL-53(Fe), was investigated. The large open channels which can accommodate small guest species, such as Li + ions, together with the redox properties of the tetravalent vanadium ions make this material of potential interest as a rechargeable intercalation electrode for lithium batteries. The electrochemical properties were investigated in Li|1 M LiPF 6 in ethylene carbonate (EC) and dimethyl carbonate (DMC)|V(O)(bdc) cells between 4.0 and 1.5 V vs. Li/Li + . V(O)(bdc) cathodes can be reversibly cycled in Li cells with good rate capability and specific capacity. At a current density of C /12, Li/V(O)(bdc) cells can be cycled between 0 ≤ x ≤ 0.7 in Li x V(O)(bdc) with ∼100% coulombic efficiency corresponding to 82 mAh g −1 which is a higher capacity than that found for MIL-53(Fe). The cell performance and electrochemical profiles at various current conditions are discussed. Structural evolution taking place during lithium intercalation was monitored by powder X-ray diffraction on phases of Li x V(O)(bdc) (0 < x ≤ 2) chemically prepared by using n-BuLi. Previous studies of the reaction of lithium with metal-organic frameworks are briefly reviewed for comparison with the data presented for Li x V(O)(bdc). [ABSTRACT FROM AUTHOR]