Rate capabilities are reported of Li/V6O13 cells at room temperature (22 degrees C) using composite gel electrolytes. The performance of cells containing base liquid electrolyte are compared with composite gel electrolytes that are formed by adding fumed silica nanoparticles to a solution of poly (ethylene glycol) dimethylether + lithium bis (trifluoromethylsulfonylimide). The dischargecharge rate capabilities are improved with addition of fumed silica. The average Coulombic efficiencies using gel electrolytes containing 10% A200, which have a native silanol surface, and 10% R805, which have an octyl-modified surface, remain at approximately 99% up to a C/2 rate, while the average Coulombic efficiency for the base liquid electrolyte decreases with increasing C rate. The improved rate capabilities for composite gel electrolytes are suggested to be related to their ability to inhibit lithium dendrite formation and form stable interfaces between electrolyte and electrodes. (c) 2006 The Electrochemical Society.