NOVELTY - The device has a solid electrolyte (300) formed of a solid polymer electrolyte that contains fine composite particles (B) comprising a polymer brush layer formed of a polymer graft chain. A negative electrode (100) or a negative electrode material layer (102) and/or a positive electrode (200) or a positive electrode material layer (202) includes gaps that are filled with the fine composite particles. The polymer brush layer is utilized as a contact interface between the solid electrolyte and the electrode material layer or the electrode.    USE - Electrochemical device e.g. lithium ion secondary battery and electrochemical capacitor (both claimed). Can also be used in nickel-hydrogen secondary battery, organic radical cell, primary battery, polymer electrolyte fuel cell, organic pigment solar cell and electrical double layer capacitor.    ADVANTAGE - The size of the electrochemical device is reduced, and the safety and reliability of the electrochemical device are improved. The heat resistance of the electrochemical device is improved. The liquid spill from the electrochemical device is prevented.    DETAILED DESCRIPTION - The device contains an ionic liquid monomer. The surface occupation rate of composite particles of polymeric graft chain is 5-50%. The molecular weight distribution index of polymeric graft chain is 1.5 or less, and the size of composite particle is 30nm-10mm. The liquid contained in the electrochemical device is an ionic liquid having compatibility with the polymeric graft chain. A bipolar electrode is arranged by inserting the solid electrolyte between the negative and positive electrodes. A mobile lithium ion is provided in the electrochemical device. An electrode-material layer is formed on sheet-like collectors (101,201), and the side of the electrode-material layer of solid electrolyte is enclosed. The electrochemical device is contacted and supported to the collector of the negative electrode and positive electrode to prevent the bending of the collector. An INDEPENDENT CLAIM is included for manufacturing method of electrochemical device, which involves forming a frame in the surroundings of the electrode-material layer with respect to the electrode. A solid electrolytic membrane is introduced into the frame. The electrode active materials are formed by impregnating the ion liquid solution of the composite particles with respect to the electrode. The electrode-material layer that overlaps the electrode plane, with which the composite particles are filled, is formed.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of the battery.    Negative electrode (100)    Collectors (101,201)    Negative electrode material layer (102)    Positive electrode (200)    Positive electrode material layer (202)    Solid electrolyte (300)    Composite particle (B)    Particulate electrode active material (P)