The sol-gel chromium-modified V6O13 as a cathodic material for lithium batteries

A new V6O13-based material has been synthesized via the sol-gel route. This sol-gel mixed oxide has been obtained from an appropriate heat treatment of the chromium-exchanged V2O5 xerogel performed under reducing atmosphere. This new compound, with the chemical formula Cr0.36V6O13.50, exhibits a monoclinic structure (C2/m) with the following unit cell parameters, a=11.89 angstrom, b=3.68 angstrom, c=10.14 angstrom, beta=101.18 degrees. The electrochemical characterization of this compound has been performed using galvanostatic discharge-charge experiments in the potential range 4-1.5 V and completed by ac impedance spectroscopy measurements. It exhibits a specific capacity of about 370 mAh g(-1), which makes the compound Cr0.36V6O13.50 the best one in the V6O13-based system: 85% of the initial capacity (315 mAh g(-1)) after the 35th cycle is still available at C/25 without any polarization. From impedance spectroscopy, a high kinetics of Li transport (D (Li)=1.8x10(-9) cm(2) supercript stop s(-1)) is found at mid-discharge.