Rechargeable aqueous lithium ion batteries have been developed by using olivine LiMn0.05Ni0.05Fe0.9PO4 as cathode material, Nasicon LiTi2(PO4)3 as anode material, and saturated Li2SO4 solution as electrolyte. The cycling performance and rate capability of these batteries have been investigated. At a current density of 0.2mA/cm2, the initial discharge capacity of the battery was approximately 103.9mAh/g, and the potential plateau was located at 0.92V. The rate capability of aqueous electrolyte was found to be preferable to that of organic electrolyte. Such inexpensive, secure and high rate rechargeable lithium ion battery should have a potential for use in many applications.