NOVELTY - An electrical storage device consists of a positive electrode (101), a negative electrode (102), and an electrolyte solution. The positive electrode contains nitroxyl compound having nitroxyl radical-cation partial structure (I) in an oxidation state and nitroxyl radical partial structure (II) in a reduction state. The electrolyte solution contains lithium salt and aprotic organic solvent. The amount of propylene carbonate contained in the electrolyte solution is 1-25 volume% with respect to the organic solvent.    USE - Electrical storage device e.g. lithium ion capacitor is used for electrical storage apparatus of solar energy and wind power generation, electric vehicle, hybrid electric vehicle, storage power supply for assistance, domestic electric appliance, and portable electronic devices e.g. notebook computer and mobile telephone.    ADVANTAGE - The electrical storage device has excellent long-term reliability and high output characteristics even in low-temperature environment.    DETAILED DESCRIPTION - An electrical storage device consists of a positive electrode, a negative electrode, and an electrolyte solution. The positive electrode contains nitroxyl compound having nitroxyl radical-cation partial structure of formula (I) in an oxidation state and nitroxyl radical partial structure of formula (II) in a reduction state. The negative electrode contains carbon material capable of reversibly inserting or detaching lithium ions. The electrolyte solution contains lithium salt and aprotic organic solvent. The amount of propylene carbonate contained in the electrolyte solution is 1-25 volume% with respect to the organic solvent. An INDEPENDENT CLAIM is included for manufacture of electrical storage device.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the lamination-type electrical storage device.    Positive electrode (101)    Negative electrode (102)    Electrical power collector (103)    Electrode lead (104)    Separator (105)