NOVELTY - An aqueous lithium ion secondary cell (10) consists of positive electrode (13) containing active material which discharges lithium ion at the time of charging and occludes lithium ion at the time of discharge, negative electrode (14), aqueous electrolyte solution (17), and separator (16) provided between the electrodes. The electrode (14) contains electrode active material which occludes lithium ion at the time of charging and discharges lithium ion at the time of discharge. The separator is hydrophilic porous polyolefin film or polyolefin non-woven fabric.    USE - Aqueous lithium ion secondary cell for use in electric vehicles and hybrid electric vehicles.    ADVANTAGE - The aqueous lithium ion secondary cell has favorable initial stage capacitance and favorable charging/discharging cycle characteristics. The separator has excellent liquid maintaining property, swelling resistance and favorable strength.    DETAILED DESCRIPTION - An aqueous lithium ion secondary cell consists of positive electrode containing active material which discharges lithium ion at the time of charging and occludes lithium ion at the time of discharge, negative electrode, aqueous electrolyte solution containing lithium salt as main electrolyte, and separator provided between the electrodes. The negative electrode contains electrode active material which occludes lithium ion at the time of charging and discharges lithium ion at the time of discharge. The separator is hydrophilic porous polyolefin film or polyolefin non-woven fabric. The polyolefin is polyethylene, polypropylene or their copolymers. The positive electrode active material contains lithium phosphoric acid compound of olivine structure having lithium and iron. The negative electrode active material contains lithium complex oxide of spinel structure containing lithium and vanadium as main component.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of aqueous lithium ion secondary cell.    Aqueous lithium ion secondary cell (10)    Positive electrode (13)    Negative electrode (14)    Separator (16)    Aqueous electrolyte solution (17)