Abstract: A lithium-ion secondary battery with a high capacity retention rate is provided. In addition, a fabricating method of a lithium-ion secondary battery with a high capacity retention rate is provided. The lithium-ion secondary battery includes a positive electrode, a negative electrode, and an electrolyte solution. The negative electrode includes a negative electrode active material layer. The electrolyte solution includes at least one of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and lithium bis(fluorosulfonyl)amide (LiFSA). The electrolyte solution includes vinylene carbonate (VC). A coating film including lithium oxide is on a surface of the negative electrode active material layer.

Abstract: A novel element is provided. A novel film formation method is provided. A novel element manufacturing method is provided. Furthermore, a film including graphene is formed at low cost and high yield. The element includes a first electrode and a second electrode located apart from the first electrode. The first electrode and the second electrode include graphene. The film including graphene is formed through a first step of forming a film including graphene oxide over a substrate, a second step of immersing the film including graphene oxide in an acidic solution, and a third step of reducing graphene oxide included in the film including graphene oxide. Furthermore, before graphene oxide included in the film including graphene oxide is reduced, the film including graphene oxide is selectively removed by a photolithography technique.

Abstract: An object is to provide graphene which has high conductivity and is permeable to ions of lithium or the like. Another object is to provide, with use of the graphene, a power storage device with excellent charging and discharging characteristics. Graphene having a hole inside a ring-like structure formed by carbon and nitrogen has conductivity and is permeable to ions of lithium or the like. The nitrogen concentration in graphene is preferably higher than or equal to 0.4 at. % and lower than or equal to 40 at. %. With use of such graphene, ions of lithium or the like can be preferably made to pass; thus, a power storage device with excellent charging and discharging characteristics can be provided.

Abstract: To provide a power storage device whose charging and discharging characteristics are unlikely to be degraded by heat treatment. To provide a power storage device that is highly safe against heat treatment. The power storage device includes a positive electrode, a negative electrode, a separator, an electrolytic solution, and an exterior body. The separator is located between the positive electrode and the negative electrode. The separator contains polyphenylene sulfide. The electrolytic solution contains a solute and two or more kinds of solvents. The solute contains LiFSA at a concentration of higher than or equal to 0.1 wt % and lower than or equal to 50 wt % in the electrolytic solution. One of the solvents is propylene carbonate.

Abstract: To provide a power storage device having excellent charge/discharge cycle characteristics and a high charge/discharge capacity. The following electrode is used as an electrode of a power storage device: an electrode including a current collector and an active material layer provided over the current collector. The active material layer includes a plurality of whisker-like active material bodies. Each of the plurality of whisker-like active material bodies includes at least a core and an outer shell provided to cover the core. The outer shell is amorphous, and a portion between the current collector and the core of the active material bodies is amorphous. Note that a metal layer may be provided instead of the current collector, the active material bodies do not necessarily have to include the core, and a mixed layer may be provided between the current collector and the active material layer.

Abstract: A power storage device a positive electrode including a positive electrode active material layer and a negative electrode including a negative electrode active material layer. The positive electrode active material layer includes a plurality of particles of x[Li2MnO3]-(1?x)[LiCo1/3Mn1/3Ni1/3O2] (obtained by assigning 0.5 to x, for example) which is a positive electrode active material, and multilayer graphene with which the plurality of particles of the positive electrode active material are at least partly connected to each other. In the multilayer graphene, a plurality of graphenes are stacked in a layered manner. The graphene contains a six-membered ring composed of carbon atoms, a poly-membered ring which is a seven or more-membered ring composed of carbon atoms, and an oxygen atom bonded to one or more of the carbon atoms in the six-membered ring and the poly-membered ring, which is a seven or more-membered ring.

Abstract: A power storage device is reduced in weight. A metal sheet serving as a negative electrode current collector is separated and another negative electrode current collector is formed. For example, through the step of forming silicon serving as a negative electrode active material layer over a titanium sheet and then performing heating, the titanium sheet can be separated. Then, another negative electrode current collector with a thickness of more than or equal to 10 nm and less than or equal to 1 ?m is formed. Thus, light weight of the power storage device can be achieved.

Abstract: A novel element is provided. A novel film formation method is provided. A novel element manufacturing method is provided. Furthermore, a film including graphene is formed at low cost and high yield. The element includes a first electrode and a second electrode located apart from the first electrode. The first electrode and the second electrode include graphene. The film including graphene is formed through a first step of forming a film including graphene oxide over a substrate, a second step of immersing the film including graphene oxide in an acidic solution, and a third step of reducing graphene oxide included in the film including graphene oxide. Furthermore, before graphene oxide included in the film including graphene oxide is reduced, the film including graphene oxide is selectively removed by a photolithography technique.

Abstract: To provide a storage battery including a carbon-based material. To provide a graphene compound film having desired ion conductivity and mechanical strength while preventing direct contact between electrodes in a storage battery. To achieve long-term reliability. A lithium-ion storage battery includes a positive electrode, a negative electrode, an exterior body, and a separator between the positive electrode and the negative electrode. In the lithium-ion storage battery, one of the positive electrode and the negative electrode is wrapped in a first film, and the positive electrode, the negative electrode, and the separator are stored in the exterior body. The first film may include a first region in which the first film includes a first functional group. The first film may further include a second region in which the first film includes a second functional group different from the first functional group. The first film may be a graphene compound film.

Abstract: To provide a power storage device with a high capacity. To provide a power storage device with a high energy density. To provide a highly reliable power storage device. To provide a long-life power storage device. To provide an electrode with a high capacity. To provide an electrode with a high energy density. To provide a highly reliable electrode. To provide a long-life electrode. The power storage device includes a first electrode and a second electrode. The first electrode includes a first current collector and a first active material layer. The first active material layer includes a first active material and a first binder. The first active material is graphite. A separation strength F of the first electrode that is measured when the first active material layer is separated from the first current collector after the first electrode is immersed in a solution at a temperature higher than or equal to 20° C. and lower than or equal to 70° C.

Abstract: Provided are an electrode for a power storage device having much better charge/discharge characteristics and a power storage device using the electrode. A plurality of cavities is provided in a surface of an active material layer over a current collector. A graphene covering the active material layer facilitates rapid charge/discharge and prevents breakdown of the current collector caused by charge/discharge. With improved charge/discharge characteristics, an electrode for a power storage device which does not easily deteriorate and a power storage device using the electrode can be provided.

Abstract: To provide a power storage device exhibiting excellent charge and discharge characteristics at high temperature. To provide a power storage device exhibiting excellent charge and discharge characteristics at a wide range of temperature. Such a power storage device includes a positive electrode, a negative electrode, a separator, and an electrolytic solution. The separator is located between the positive electrode and the negative electrode and contains polyphenylene sulfide. The electrolytic solution contains an ionic liquid and an alkali metal salt.

Abstract: To provide a method of manufacturing a lithium-ion secondary battery having stable charge characteristics and lifetime characteristics. A positive electrode is subjected to an electrochemical reaction in a large amount of electrolytic solution in advance before a secondary battery is completed. In this manner, the positive electrode can have stability. The use of the positive electrode enables manufacture of a highly reliable secondary battery. Similarly, a negative electrode is subjected to an electrochemical reaction in a large amount of electrolytic solution in advance. The use of the negative electrode enables manufacture of a highly reliable secondary battery.

Abstract: A power storage device in which silicon is used as a negative electrode active material layer and which can have an improved performance such as higher discharge capacity, and a method for manufacturing the power storage device are provided. A power storage device includes a current collector and a silicon layer having a function as an active material layer over the current collector. The silicon layer includes a thin film portion in contact with the current collector, a plurality of bases, and a plurality of whisker-like protrusions extending from the plurality of bases. A protrusion extending from one of the plurality of bases is partly combined with a protrusion extending from another one of the plurality of bases.

Abstract: When cellulose is used as a separator, the cellulose is impregnated with an ionic liquid. Charge and discharge are repeated with this separator touching a surface of a current collector; then, the separator is changed in color. Thus, it is an object to provide a power storage device with a structure in which a side reaction other than a battery reaction, e.g., a change in color of separator, is unlikely to occur. In the power storage device, a separator impregnated with an ionic liquid is not in contact with a surface of a current collector. The separator has a tubular shape, a bag-like shape, or a sheet-like shape. The separator includes cellulose. The power storage device including the ionic liquid is non-volatile and non-flammable. The power storage device can be bent.

Abstract: A lithium-ion storage battery with a favorable cycle life at high temperatures is provided. A lithium-ion storage battery with a longer lifetime due to reduction of the capacity decrease is provided. A lithium-ion storage battery where reaction between a positive electrode active material and an electrolyte in an electrolyte solution is inhibited is provided. One embodiment of the present invention is a lithium-ion storage battery including a positive electrode, a negative electrode, an electrolyte solution. The positive electrode includes an active material, the active material includes a metal, and the electrolyte solution includes at least one of LiTFSA and LiFSA. Note that, in the lithium-ion storage battery of one embodiment of the present invention, the positive electrode may include a current collector, and the current collector may include Al. In the lithium-ion storage battery, the electrolyte solution may further include LiPF6.

Abstract: A lithium-ion storage battery with a high capacity retention rate is provided. A lithium-ion storage battery with a longer lifetime is provided. A method for fabricating a lithium-ion storage battery with a high capacity retention rate is provided. A lithium-ion storage battery includes a positive electrode, a negative electrode, and an electrolyte solution. A coating film which includes lithium oxide is provided over the surface of the negative electrode. The electrolyte solution may include LiTFSA or LiFSA. The method for fabricating a lithium-ion storage battery includes a first step of enclosing a positive electrode, a negative electrode, and an electrolyte solution in an exterior body and a second step of keeping the exterior body including the positive electrode, the negative electrode, and the electrolyte solution at temperature higher than or equal to 70 degrees Celsius for longer than or equal to 24 hours after the first step.

Abstract: An object is to provide graphene which has high conductivity and is permeable to ions of lithium or the like. Another object is to provide, with use of the graphene, a power storage device with excellent charging and discharging characteristics. Graphene having a hole inside a ring-like structure formed by carbon and nitrogen has conductivity and is permeable to ions of lithium or the like. The nitrogen concentration in graphene is preferably higher than or equal to 0.4 at. % and lower than or equal to 40 at. %. With use of such graphene, ions of lithium or the like can be preferably made to pass; thus, a power storage device with excellent charging and discharging characteristics can be provided.

Abstract: A power storage device is reduced in weight. A metal sheet serving as a negative electrode current collector is separated and another negative electrode current collector is formed. For example, through the step of forming silicon serving as a negative electrode active material layer over a titanium sheet and then performing heating, the titanium sheet can be separated. Then, another negative electrode current collector with a thickness of more than or equal to 10 nm and less than or equal to 1 ?m is formed. Thus, light weight of the power storage device can be achieved.

Abstract: An object is to provide graphene which has high conductivity and is permeable to ions of lithium or the like. Another object is to provide, with use of the graphene, a power storage device with excellent charging and discharging characteristics. Graphene having a hole inside a ring-like structure formed by carbon and nitrogen has conductivity and is permeable to ions of lithium or the like. The nitrogen concentration in graphene is preferably higher than or equal to 0.4 at. % and lower than or equal to 40 at. %. With use of such graphene, ions of lithium or the like can be preferably made to pass; thus, a power storage device with excellent charging and discharging characteristics can be provided.