NOVELTY - A power storage device (100) comprises positive electrode (111); negative electrode (101), electrolyte (121) between positive electrode and negative electrode, where the electrolyte includes an ion-conductive high molecular compound, an inorganic oxide, and a lithium salt; and the inorganic oxide is included in the electrolyte at 30-50 wt.% to the total of the ion-conductive high molecular compound and the inorganic oxide.    USE - As power storage device (claimed) e.g. lithium-ion secondary battery and a lithium-ion capacitor.    ADVANTAGE - The lithium-ion secondary battery has a small memory effect, high energy density, large capacity, and high output voltage. Thus, the size and weight of the lithium ion secondary battery can be reduced. The lithium ion secondary battery does not easily degrade due to repetitive charge and discharge and can be used for a long time, so that cost can be reduced. Since the electrolyte includes both an inorganic oxide and an ion-conductive high molecular compound, crystallization of the ion-conductive high molecular compound is suppressed, so that the ion conductivity of the electrolyte is increased. As a result, transfer of mobile ions between the positive electrode and the negative electrode can be easy, so that a charge-discharge capacity can be increased.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacturing a power storage device involving mixing an ion-conductive high molecular compound, an inorganic oxide, and a lithium salt for forming slurry; coating a substrate with the slurry; drying the slurry for forming an electrolyte; separating the electrolyte from the substrate; and sandwiching the electrolyte between a positive electrode and a negative electrode.    DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of power storage device.    Power storage device (100)    Negative electrode (101)    Negative electrode current collector (102)    Negative electrode active material layer (103)    Positive electrode (111)    Positive electrode current collector (112)    Positive electrode active material layer (113)    Electrolyte (121)