▎ 摘　　要

NOVELTY - The secondary battery (100) has a first electrode containing a positive electrode active material. A second electrode includes a negative electrode active material. A layer (103) contains a graphene compound. The layer containing a graphene compound has ion conductivity and is configured to prevent a short circuit between the first electrode and the second electrode. The layer containing a graphene compound includes oxygen and a functional group. The functional group is ether or ester. The layer containing a graphene compound further includes silicon. The layer containing a graphene compound includes a graphene oxide, where the silicon is bonded to oxygen of the graphene oxide, and the functional group is bonded to the silicon. An end portion of the graphene compound is terminated with ester and is chemically modified with an alkyl group. USE - Lithium-ion secondary battery such as power storage device for portable mobile electronic device and wearable electronic device. Uses include but are not limited to mobile electronic device, medical equipment, next-generation clean energy vehicle such as hybrid electric vehicle (HEV), electric vehicle (EV) and plug-in hybrid electric vehicle (PHEV), hearing aid, imaging device, vacuum cleaner, electric tool, electric shaver, lighting device, toy, medical device, robot, electric vehicle e.g. hybrid car, power storage source of building e.g. house, two-wheeled motor vehicle such as scooter, boarding-type mobile assistive robot. ADVANTAGE - The appropriate molecule is bonded or adsorbed to a graphene compound, so that the surface of the graphene compound is chemically modified, since the layer for preventing a short circuit between the positive electrode and the negative electrode is formed. Since a graphene compound is resistant to deformation, a solid electrolyte using the graphene compound is prevented from being deformed by an external pressure. The graphite is preferred because it has relatively high capacity per unit volume, relatively small volume expansion, low cost, and higher level of safety than that of a lithium metal. The graphene compound has excellent electrical characteristics of high conductivity and excellent physical properties of high flexibility and high mechanical strength. The graphene oxide has relatively low electron conductivity, and it has low reduction resistance and thus is easily reduced to RGO having high electron conductivity. The high durability is especially important for a lithium-ion secondary battery to prevent a serious accident such as firing or explosion caused by an unexpected reaction due to damage to a component in the battery. The power storage device has high capacity and excellent cycle characteristics, the small and lightweight vaporizer which is used for a long time for a long period is provided. The power storage devices of these products are handling ease for users, small and lightweight stick type power storage devices with high capacity are desired. DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a power storage device. Lithium-ion secondary battery (100) Positive electrode (101) Negative electrode (102) Layer (103)