Abstract: A battery module with high impact resistance is provided. A battery module using an elastic body such as rubber for its exterior body covering a battery is provided. A bendable battery module is provided. As the exterior body covering a battery, an elastic body such as rubber is used, and the exterior body is molded in two steps. First, a first portion provided with a depression in which a battery is stored is molded using a first mold. Next, a battery is inserted into the first portion. Subsequently, second molding is performed using a second mold so as to fill an opening of the depression in the first portion, so that a second portion is formed. The second portion serves as a cover for closing the opening of the depression in the first portion. The second portion is formed in contact with part of the electrodes in the battery and part of an end portion of the second exterior body in the battery.

Abstract: A negative electrode active material with high capacity and excellent cycle performance and rate performance is provided. In addition, a secondary battery including the negative electrode active material, and an electronic device including the secondary battery are provided. Nanosilicon is mixed with a solid electrolyte containing lithium, titanium, phosphorus, and oxygen, and graphene oxide is further added thereto. Then, graphene oxide contained in the mixture is reduced with ethanol in which ascorbic acid and lithium hydroxide hydrate are dissolved, so that the negative electrode active material is manufactured.

Abstract: A storage battery includes positive and negative electrodes and an electrolytic solution. The negative electrode includes a first element and carbon. The first element is any of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. The negative electrode includes an active material and a first layer in contact with a surface of the active material. The first layer has a thickness of 10 nm to 1000 nm inclusive. The electrolytic solution contains first and second cations. The first cation is one or more of a lithium ion, a sodium ion, a calcium ion, and a magnesium ion. The second cation is an imidazolium cation or a tertiary sulfonium cation.

Abstract: A storage battery includes positive and negative electrodes and an electrolytic solution. The negative electrode includes a first element and carbon. The first element is any of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. The negative electrode includes an active material and a first layer in contact with a surface of the active material. The first layer has a thickness of 10 nm to 1000 nm inclusive. The electrolytic solution contains first and second cations. The first cation is one or more of a lithium ion, a sodium ion, a calcium ion, and a magnesium ion. The second cation is an imidazolium cation or a tertiary sulfonium cation.

Abstract: To provide a power storage device whose charge and discharge 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 or solvent-spun regenerated cellulosic fiber The electrolytic solution contains a solute and two or more kinds of solvents. The solute contains LiBETA. One of the solvents is propylene carbonate.

Abstract: To provide a power storage device whose charge and discharge 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 or solvent-spun regenerated cellulosic fiber. The electrolytic solution contains a solute and two or more kinds of solvents. The solute contains LiBETA. One of the solvents is propylene carbonate.

Abstract: A power storage device with high capacity is provided. Alternatively, a power storage device with high energy density is provided. Alternatively, a highly reliable power storage device is provided. Alternatively, a long-life power storage device is provided. A power storage device is characterized by comprising a separator, a first electrode, a second electrode, an electrolytic solution, in which the separator is provided between the first electrode and the second electrode, the first electrode includes an active material layer and a current collector, the first electrode includes a pair of coating films between which the current collector is sandwiched, the active material layer includes a region in contact with the current collector, the active material layer includes a region in contact with at least one of the pair of coating films, and the electrolytic solution includes an alkali metal salt and an ionic liquid.

Abstract: Provided is a power storage device whose charging and discharging characteristics are unlikely to be degraded by heat treatment or 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 electrolyte, and an exterior body. The separator is positioned between the positive electrode and the negative electrode and includes polyphenylene sulfide or cellulosic fiber. The electrolyte includes propylene carbonate, ethylene carbonate, and vinylene carbonate, lithium hexafluorophosphate, and lithium bis(pentafluoroethanesulfonyl)amide. A concentration of lithium hexafluorophosphate with respect to the electrolyte is more than or equal to 0.01 wt % and less than or equal to 1.9 wt % in a weight ratio.

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 power storage device with high capacity is provided. Alternatively, a power storage device with high energy density is provided. Alternatively, a highly reliable power storage device is provided. Alternatively, a long-life power storage device is provided. A power storage device is characterized by comprising a separator, a first electrode, a second electrode, an electrolytic solution, in which the separator is provided between the first electrode and the second electrode, the first electrode includes an active material layer and a current collector, the first electrode includes a pair of coating films between which the current collector is sandwiched, the active material layer includes a region in contact with the current collector, the active material layer includes a region in contact with at least one of the pair of coating films, and the electrolytic solution includes an alkali metal salt and an ionic liquid.

Abstract: A battery module with high impact resistance is provided. A battery module using an elastic body such as rubber for its exterior body covering a battery is provided. A bendable battery module is provided. As the exterior body covering a battery, an elastic body such as rubber is used, and the exterior body is molded in two steps. First, a first portion provided with a depression in which a battery is stored is molded using a first mold. Next, a battery is inserted into the first portion. Subsequently, second molding is performed using a second mold so as to fill an opening of the depression in the first portion, so that a second portion is formed. The second portion serves as a cover for closing the opening of the depression in the first portion. The second portion is formed in contact with part of the electrodes in the battery and part of an end portion of the second exterior body in the battery.

Abstract: A power storage device with a high capacity is provided. A power storage device with a high energy density is provided. A highly reliable power storage device is provided. A power storage device with a long lifetime is provided. A method for manufacturing an electrode is characterized by including the steps of: mixing an active material, a binder, and a conductive additive to form a slurry; applying the slurry onto a current collector; drying the applied slurry to form an active material layer; and performing heat treatment in an atmosphere containing oxygen to form a film in contact with the current collector. The film is formed on a surface of the current collector where the active material layer is not provided and includes at least one component of the current collector and oxygen.

Abstract: A storage battery includes positive and negative electrodes and an electrolytic solution. The negative electrode includes a first element and carbon. The first element is any of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, and indium. The negative electrode includes an active material and a first layer in contact with a surface of the active material. The first layer has a thickness of 10 nm to 1000 nm inclusive. The electrolytic solution contains first and second cations. The first cation is one or more of a lithium ion, a sodium ion, a calcium ion, and a magnesium ion. The second cation is an imidazolium cation or a tertiary sulfonium cation.

Abstract: To provide a power storage device whose charge and discharge 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 or solvent-spun regenerated cellulosic fiber. The electrolytic solution contains a solute and two or more kinds of solvents. The solute contains LiBETA. One of the solvents is propylene carbonate.

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 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: 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.