Abstract: A sturdy electronic device is provided. A reliable electronic device is provided. A novel electronic device is provided. An electronic device includes a first board, a second board, a display portion having flexibility, and a power storage device having flexibility. The first board and the second board face each other. The display portion and the power storage device are provided between the first board and the second board. The display portion includes a first surface facing the power storage device. The first surface includes a first region not fixed to the power storage device. The first region overlaps with a display region of the display portion.

Abstract: A wearable device needs to have a design corresponding to complicated surfaces of human bodies. Thus, an electronic device that can fit the characteristics of each individual human body after being purchased and can be worn naturally and comfortably is provided. The electronic device includes a secondary battery which can be transformed. By using a secondary battery which can be transformed, for example, a secondary battery can be efficiently placed in a narrow and elongated space in the electronic device, and the elongated secondary battery can be bent together with the electronic device. Furthermore, the weight balance of the electronic device can be easily adjusted.

Abstract: A gel electrolyte and a separator are provided between the positive electrode current collector and the negative electrode current collector. The plurality of positive electrode current collectors and the plurality of negative electrode current collectors are stacked such that surfaces of negative electrodes with which active material layers are not coated or surfaces of positive electrodes with which active material layers are not coated are in contact with each other.

Abstract: A highly portable and highly browsable light-emitting device is provided. A light-emitting device that is less likely to be broken is provided. The light-emitting device has a strip-like region having high flexibility and a strip-like region having low flexibility that are arranged alternately. In the region having high flexibility, a light-emitting panel and a plurality of spacers overlap with each other. In the region having low flexibility, the light-emitting panel and a support overlap with each other. When the region having high flexibility is bent, the angle between normals of facing planes of the two adjacent spacers changes according to the bending of the light-emitting panel; thus, a neutral plane can be formed in the light-emitting panel or in the vicinity of the light-emitting panel.

Abstract: A structure suitable for a portable information terminal or a wearable device is provided. In addition, an electronic device having a novel structure that can have various forms is provided. It is preferable that a buffer layer which absorbs a difference in the amount of change in form be provided between adjacent film substrates which overlap with each other. As the buffer layer, a gelled resin material, a rubber resin material, a liquid material, an air layer, or the like can be used. Furthermore, an optical film such as a polarizing film or a color filter may be used as the buffer layer. A plurality of buffer layers may be provided in an electronic device.

Abstract: To provide a secondary battery that is suitable to a portable information terminal or a wearable device. To provide an electronic device having a novel structure that can have various forms and a secondary battery that fits the forms of the electronic device. The secondary battery includes a film provided with depressions or projections that can ease stress on the film due to application of external force. The sizes of the depressions or projections are different between a center portion and an end portion of the film. The end portion of the film is sealed with an adhesive layer. The depressions or projections of the film are formed by pressing such as embossing.

Abstract: An electronic device of a novel embodiment, specifically an arm-worn electronic device used while being worn on an arm, is provided. An arm-worn secondary battery used while being worn on an arm is provided. An electronic device is provided, which includes a structure body having a curved surface as a support structure body, a flexible secondary battery including a film as an exterior body over the curved surface of the support structure body, and a display portion including a plurality of display elements between a pair of films over the secondary battery. The plurality of display elements and the secondary battery overlap with each other at least partly. It is possible to provide an electronic device which has a small maximum thickness of 1 cm or less and a light weight of 50 g or less even when an arm-worn secondary battery is provided with a display portion.

Abstract: A highly portable and highly browsable light-emitting device is provided. A light-emitting device that is less likely to be broken is provided. The light-emitting device has a strip-like region having high flexibility and a strip-like region having low flexibility that are arranged alternately. In the region having high flexibility, a light-emitting panel and a plurality of spacers overlap with each other. In the region having low flexibility, the light-emitting panel and a support overlap with each other. When the region having high flexibility is bent, the angle between normals of facing planes of the two adjacent spacers changes according to the bending of the light-emitting panel; thus, a neutral plane can be formed in the light-emitting panel or in the vicinity of the light-emitting panel.

Abstract: A sturdy electronic device is provided. A reliable electronic device is provided. A novel electronic device is provided. An electronic device includes a first board, a second board, a display portion having flexibility, and a power storage device having flexibility. The first board and the second board face each other. The display portion and the power storage device are provided between the first board and the second board. The display portion includes a first surface facing the power storage device. The first surface includes a first region not fixed to the power storage device. The first region overlaps with a display region of the display portion.

Abstract: A structure suitable for a portable information terminal or a wearable device is provided. In addition, an electronic device having a novel structure that can have various forms is provided. It is preferable that a buffer layer which absorbs a difference in the amount of change in form be provided between adjacent film substrates which overlap with each other. As the buffer layer, a gelled resin material, a rubber resin material, a liquid material, an air layer, or the like can be used. Furthermore, an optical film such as a polarizing film or a color filter may be used as the buffer layer. A plurality of buffer layers may be provided in an electronic device.

Abstract: Part of an electrode, specifically a current collector and an active material layer, for a secondary battery is subjected to cutting processing to have a complex shape. For example, a stack of the first current collector and the first active material layer has a first slit and a second slit. Each of the first slit and the second slit passing across the first current collector and the first active material layer and extending from an edge of the first current collector. Another stack of the second current collector and the second active material layer has a third slit and a fourth slit. Each of the third slit and the fourth slit passing across the second current collector and the second active material layer and extending from an edge of the second current collector.

Abstract: To provide a secondary battery that is suitable to a portable information terminal or a wearable device. To provide an electronic device having a novel structure that can have various forms and a secondary battery that fits the forms of the electronic device. The secondary battery includes a film provided with depressions or projections that can ease stress on the film due to application of external force. The sizes of the depressions or projections are different between a center portion and an end portion of the film. The end portion of the film is sealed with an adhesive layer. The depressions or projections of the film are formed by pressing such as embossing.

Abstract: An electronic device of a novel embodiment, specifically an arm-worn electronic device used while being worn on an arm, is provided. An arm-worn secondary battery used while being worn on an arm is provided. An electronic device is provided, which includes a structure body having a curved surface as a support structure body, a flexible secondary battery including a film as an exterior body over the curved surface of the support structure body, and a display portion including a plurality of display elements between a pair of films over the secondary battery. The plurality of display elements and the secondary battery overlap with each other at least partly. It is possible to provide an electronic device which has a small maximum thickness of 1 cm or less and a light weight of 50 g or less even when an arm-worn secondary battery is provided with a display portion.

Abstract: A sturdy electronic device is provided. A reliable electronic device is provided. A novel electronic device is provided. An electronic device includes a first board, a second board, a display portion having flexibility, and a power storage device having flexibility. The first board and the second board face each other. The display portion and the power storage device are provided between the first board and the second board. The display portion includes a first surface facing the power storage device. The first surface includes a first region not fixed to the power storage device. The first region overlaps with a display region of the display portion.

Abstract: Disclosed is a power storage unit which can safely operate over a wide temperature range. The power storage unit includes: a power storage device; a heater for heating the power storage device; a temperature sensor for sensing the temperature of the power storage device; and a control circuit configured to inhibit charge of the power storage device when its temperature is lower than a first temperature or higher than a second temperature. The first temperature is exemplified by a temperature which allows the formation of a dendrite over a negative electrode of the power storage device, whereas the second temperature is exemplified by a temperature which causes decomposition of a passivating film formed over a surface of a negative electrode active material.

Abstract: A structure suitable for a portable information terminal or a wearable device is provided. In addition, an electronic device having a novel structure that can have various forms is provided. It is preferable that a buffer layer which absorbs a difference in the amount of change in form be provided between adjacent film substrates which overlap with each other. As the buffer layer, a gelled resin material, a rubber resin material, a liquid material, an air layer, or the like can be used. Furthermore, an optical film such as a polarizing film or a color filter may be used as the buffer layer. A plurality of buffer layers may be provided in an electronic device.

Abstract: Part of an electrode, specifically a current collector and an active material layer, for a secondary battery is subjected to cutting processing to have a complex shape. For example, a stack of the first current collector and the first active material layer has a first slit and a second slit. Each of the first slit and the second slit passing across the first current collector and the first active material layer and extending from an edge of the first current collector. Another stack of the second current collector and the second active material layer has a third slit and a fourth slit. Each of the third slit and the fourth slit passing across the second current collector and the second active material layer and extending from an edge of the second current collector.

Abstract: A highly portable and highly browsable light-emitting device is provided. A light-emitting device that is less likely to be broken is provided. The light-emitting device has a strip-like region having high flexibility and a strip-like region having low flexibility that are arranged alternately. In the region having high flexibility, a light-emitting panel and a plurality of spacers overlap with each other. In the region having low flexibility, the light-emitting panel and a support overlap with each other. When the region having high flexibility is bent, the angle between normals of facing planes of the two adjacent spacers changes according to the bending of the light-emitting panel; thus, a neutral plane can be formed in the light-emitting panel or in the vicinity of the light-emitting panel.

Abstract: Disclosed is a power storage unit which can safely operate over a wide temperature range. The power storage unit includes: a power storage device; a heater for heating the power storage device; a temperature sensor for sensing the temperature of the power storage device; and a control circuit configured to inhibit charge of the power storage device when its temperature is lower than a first temperature or higher than a second temperature. The first temperature is exemplified by a temperature which allows the formation of a dendrite over a negative electrode of the power storage device, whereas the second temperature is exemplified by a temperature which causes decomposition of a passivating film formed over a surface of a negative electrode active material.

Abstract: A structure suitable for a portable information terminal or a wearable device is provided. In addition, an electronic device having a novel structure that can have various forms is provided. It is preferable that a buffer layer which absorbs a difference in the amount of change in form be provided between adjacent film substrates which overlap with each other. As the buffer layer, a gelled resin material, a rubber resin material, a liquid material, an air layer, or the like can be used. Furthermore, an optical film such as a polarizing film or a color filter may be used as the buffer layer. A plurality of buffer layers may be provided in an electronic device.