TECHNOLOGY FOCUS - ELECTRONICS - Preferred Composition: (I) is disposed so as to be in contact with at least one of a cathode and an anode, where the concentration of the ceramic powder in a contact portion that contacts the cathode and/or the anode is higher than that in an electrode surface portion of the cathode and/or the anode that contacts the contact portion. Preferred Components: The cathode includes a belt-shaped cathode collector and a cathode active material layer that is stacked on the cathode collector and contains a cathode active material, the anode includes a belt-shaped anode collector and an anode active material layer that is stacked on the anode collector and contains an anode active material, the nonaqueous electrolyte includes extending portions formed so as to protrude from the cathode active material layer and the anode active material layer in a direction perpendicular to a stacking direction, and the extending portions cover a width of 0.1-5 mm (preferably 0.1-2 mm) from a side edge of at least one of the cathode active material layer and the anode active material layer. The amount of the ceramic powder per unit area between the cathode and the anode is 0.6-3.5 mg/cm2. The nonaqueous electrolyte material has a viscosity of 40-70 mPa.s. The nonaqueous electrolyte material further includes a viscosity-adjusting solvent.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The ceramic powder comprises aluminum oxide, zirconium oxide, titanium oxide or magnesium oxide. The content ratio of the ceramic powder to the matrix polymer is 1/1 to 5/1 by mass. The electrolyte salt is a lithium salt, and the concentration of the lithium salt in (I) is 0.6-2 mole/kg.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The matrix polymer contains polyvinylidene fluoride and has a weight-average molecular weight of 550000 or more. EXAMPLE - Pulverized artificial graphite powder (90 parts by weight (pbw)) and polyvinylidene fluoride (PVdF) (10 pbw) were dispersed in N-methyl-2-pyrrolidone to prepare a slurry. The slurry was uniformly applied on both surfaces of belt-shaped copper foil and dried. The resultant body was press-formed using a roll press machine to manufacture an anode. Subsequently, lithium cobalt oxide (91 pbw), graphite (6 pbw) and PVdF (10 pbw) were dispersed in N-methyl-2-pyrrolidone to prepare a slurry. The slurry was uniformly applied on belt-shaped aluminum foil and dried. The resultant body was press-formed using a roll press machine to manufacture a cathode. The PVdF (10 pbw) was dissolved in the nonaqueous electrolytic solution (90 pbw), and aluminum oxide or ceramic were added to the mixed solution to give a gel nonaqueous electrolyte.