Abstract: To improve the long-term cycle performance of a lithium-ion battery or a lithium-ion capacitor by minimizing the decomposition reaction of an electrolytic solution and the like as a side reaction of charge and discharge in the repeated charge and discharge cycles of the lithium-ion battery or the lithium-ion capacitor. A current collector and an active material layer over the current collector are included in an electrode for a power storage device. The active material layer includes a plurality of active material particles and silicon oxide. The surface of one of the active material particles has a region that is in contact with one of the other active material particles. The surface of the active material particle except the region is partly or entirely covered with the silicon oxide.

Abstract: A power storage system or a power storage device that can restore reduced capacity is provided. The power storage device includes a first exterior body, a first electrode, a second electrode, a first electrolyte solution, and a carrier ion permeable film. The first electrode, the second electrode, and the first electrolyte solution are covered with the first exterior body. The first electrode and the second electrode are in contact with the first electrolyte solution. The first electrolyte solution includes carrier ions. A first opening is provided in the first exterior body. The carrier ion permeable film is provided to be in contact with the first electrolyte solution and so as to block the first opening without any space. The carrier ion permeable film is configured to be impermeable to water and air but permeable to the carrier ions.

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: To provide a fabricating method and a fabricating apparatus for 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 fabrication 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 fabrication of a highly reliable secondary battery.

Abstract: To improve the long-term cycle performance of a lithium-ion battery or a lithium-ion capacitor by minimizing the decomposition reaction of an electrolytic solution and the like as a side reaction of charge and discharge in the repeated charge and discharge cycles of the lithium-ion battery or the lithium-ion capacitor. A current collector and an active material layer over the current collector are included in an electrode for a power storage device. The active material layer includes a plurality of active material particles and silicon oxide. The surface of one of the active material particles has a region that is in contact with one of the other active material particles. The surface of the active material particle except the region is partly or entirely covered with the silicon oxide.

Abstract: A lithium ion secondary battery includes a positive electrode including a positive electrode active material layer containing lithium iron phosphate, a negative electrode including a negative electrode active material layer containing graphite, and an electrolyte including a lithium salt and a solvent including ethylene carbonate and diethyl carbonate between the positive electrode and the negative electrode. When the battery temperature of the lithium ion secondary battery or the temperature of an environment in which the lithium ion secondary battery is used is T and given temperatures are T1 and T2 (T1<T2), in the case where T<T1, constant current charge is performed until voltage reaches a given value and then constant voltage charge is performed; in the case where T1?T<T2, only constant current charge is performed; and in the case where T2?T, charge is not performed.

Abstract: An object is to reduce variation in shape of crystals that are to be formed. Solutions containing respective raw materials are made in an environment where an oxygen concentration is lower than that in air, the solutions containing the respective raw materials are mixed in an environment where an oxygen concentration is lower than that in air to form a mixture solution, and with use of the mixture solution, a composite oxide is formed by a hydrothermal method.

Abstract: An object is to suppress electrochemical decomposition of an electrolyte solution and the like at a negative electrode in a lithium ion battery or a lithium ion capacitor: thus, irreversible capacity is reduced, cycle performance is improved, or operating temperature range is extended. A negative electrode for a power storage device including a negative electrode current collector, a negative electrode active material layer which is over the negative electrode current collector and includes a plurality of particles of a negative electrode active material, and a film covering part of the negative electrode active material. The film has an insulating property and lithium ion conductivity.

Abstract: A semiconductor device in which a circuit and a battery are efficiently stored is provided. In the semiconductor device, a first transistor, a second transistor, and a secondary battery are provided over one substrate. A channel region of the second transistor includes an oxide semiconductor. The secondary battery includes a solid electrolyte, and can be fabricated by a semiconductor manufacturing process. The substrate may be a semiconductor substrate or a flexible substrate. The secondary battery has a function of being wirelessly charged.

Abstract: To increase the conductivity and electric capacity of an electrode which includes active material particles and the like and is used in a battery, a graphene net including 1 to 100 graphene sheets is used instead of a conventionally used conduction auxiliary agent and binder. The graphene net which has a two-dimensional expansion and a three-dimensional structure is more likely to touch active material particles or another conduction auxiliary agent, thereby increasing the conductivity and the bonding strength between active material particles. This graphene net is obtained by mixing graphene oxide and active material particles and then heating the mixture in a vacuum or a reducing atmosphere.

Abstract: A semiconductor device in which a circuit and a power storage element are efficiently placed is provided. The semiconductor device includes a first transistor, a second transistor, and an electric double-layer capacitor. The first transistor, the second transistor, and the electric double-layer capacitor are provided over one substrate. A band gap of a semiconductor constituting a channel region of the second transistor is wider than a band gap of a semiconductor constituting a channel region of the first transistor. The electric double-layer capacitor includes a solid electrolyte.

Abstract: A lithium ion secondary battery includes a positive electrode including a positive electrode active material layer containing lithium iron phosphate, a negative electrode including a negative electrode active material layer containing graphite, and an electrolyte including a lithium salt and a solvent including ethylene carbonate and diethyl carbonate between the positive electrode and the negative electrode. When the battery temperature of the lithium ion secondary battery or the temperature of an environment in which the lithium ion secondary battery is used is T and given temperatures are T1 and T2 (T1<T2), in the case where T<T1, constant current charge is performed until voltage reaches a given value and then constant voltage charge is performed; in the case where T1?T<T2, only constant current charge is performed; and in the case where T2?T, charge is not performed.

Abstract: A semiconductor device in which a circuit and a battery are efficiently stored is provided. In the semiconductor device, a first transistor, a second transistor, and a secondary battery are provided over one substrate. A channel region of the second transistor includes an oxide semiconductor. The secondary battery includes a solid electrolyte, and can be fabricated by a semiconductor manufacturing process. The substrate may be a semiconductor substrate or a flexible substrate. The secondary battery has a function of being wirelessly charged.

Abstract: An object is to reduce variation in shape of crystals that are to be formed. Solutions containing respective raw materials are made in an environment where an oxygen concentration is lower than that in air, the solutions containing the respective raw materials are mixed in an environment where an oxygen concentration is lower than that in air to form a mixture solution, and with use of the mixture solution, a composite oxide is formed by a hydrothermal method.

Abstract: An object is to suppress electrochemical decomposition of an electrolyte solution and the like at a negative electrode in a lithium ion battery or a lithium ion capacitor; thus, irreversible capacity is reduced, cycle performance is improved, or operating temperature range is extended. A negative electrode for a power storage device including a negative electrode current collector, a negative electrode active material layer which is over the negative electrode current collector and includes a plurality of particles of a negative electrode active material, and a film covering part of the negative electrode active material. The film has an insulating property and lithium ion conductivity.

Abstract: To increase the conductivity and electric capacity of an electrode which includes active material particles and the like and is used in a battery, a graphene net including 1 to 100 graphene sheets is used instead of a conventionally used conduction auxiliary agent and binder. The graphene net which has a two-dimensional expansion and a three-dimensional structure is more likely to touch active material particles or another conduction auxiliary agent, thereby increasing the conductivity and the bonding strength between active material particles. This graphene net is obtained by mixing graphene oxide and active material particles and then heating the mixture in a vacuum or a reducing atmosphere.

Abstract: A novel element, a novel formation method of a film, or a novel formation method of an element is provided. Alternatively, a film including graphene is formed at low cost and high yield. A formation method of a film including graphene includes a first step of forming a film including graphene oxide that includes a first region and a second region by application of a dispersion liquid in which graphene oxide is dispersed over a substrate and removal of dispersion medium from the applied dispersion liquid, a second step of forming a film including graphene by light irradiation to the first region to reduce the first region, and a third step of removing the second region by washing.

Abstract: A semiconductor device in which a circuit and a power storage element are efficiently placed is provided. The semiconductor device includes a first transistor, a second transistor, and an electric double-layer capacitor. The first transistor, the second transistor, and the electric double-layer capacitor are provided over one substrate. A band gap of a semiconductor constituting a channel region of the second transistor is wider than a band gap of a semiconductor constituting a channel region of the first transistor. The electric double-layer capacitor includes a solid electrolyte.

Abstract: A secondary battery module capable of feeding power to a wearable device in a non-contact manner is provided. A power feeding system for an electronic device is provided. The power feeding system includes a secondary battery module and an electronic device. The secondary battery module includes a flexible secondary battery, a power sending portion for non-contact power transmission, a flexible thermoelectric power generating device, and a belt portion storing the flexible secondary battery and the flexible thermoelectric power generating device. The electronic device includes a power receiving portion for non-contact power transmission and is capable of power transmission from the power sending portion for non-contact power transmission which is included in the secondary battery module to the power receiving portion for non-contact power transmission which is included in the electronic device.

Abstract: A fabricating method and a fabricating apparatus for a lithium-ion secondary battery having stable charge characteristics and lifetime characteristics are provided. A positive electrode is subjected to an electrochemical reaction in a large amount of electrolyte solution in advance before a secondary battery is completed. In this manner, the positive electrode can have stability. In a manner similar to that of the positive electrode, a negative electrode is also subjected to the electrochemical reaction in a large amount of the electrolyte solution in advance, whereby a high reliable secondary battery can be manufactured.