A novel type of 2 V rocking-chair lithium batteries with nano-crystalline TiO2 (anatase) as the negative and LiNi0.5Co0.5O2 as the positive electrode with LiN(CF3SO2)(2)+ethylene carbonate/dimethoxyethane electrolyte has been studied. The closed R921 button cells showed excellent cycling performance and a charge density of about 50 mAh/g. The advantages of the specific porous morphology of nano-crystalline insertion materials for Li insertion and release are discussed.