Abstract: To provide a positive electrode active material in which a phase transition is inhibited and a secondary battery including the positive electrode active material. An unprecedented synthesis method has been developed in which lithium cobalt oxide particles are treated with a molten salt of MgF2—LiF as a reaction accelerator to facilitate the diffusion and doping of magnesium into lithium cobalt oxide bulk and to form a stable coating layer in the particle surface portion. Ex situ XRD analysis confirms the inhibition of the harmful phase transition and the emergence of a novel phase as the modified LiCoO2 is charged up to 4.7 V. The modified LiCoO2 shows high electrochemical performance during high-voltage operation. This technology provides a guideline for suppressing fundamental degradation associated with phase transition and achieving ultra-high energy density LiCoO2 positive electrodes.

Abstract: A positive electrode and a secondary battery that are stable in a high potential state and/or a high temperature state are provided. Alternatively, a positive electrode and a secondary battery that have excellent cycle performance are provided. The positive electrode includes a positive electrode active material and a conductive material; at least part of a surface of the positive electrode active material is covered with the conductive material; the positive electrode active material includes lithium cobalt oxide containing magnesium, fluorine, aluminum, and nickel; the lithium cobalt oxide includes a region in which at least one or more concentrations of the magnesium, the fluorine, and the aluminum are the maximum in a surface portion; and the conductive material contains carbon. The conductive material is preferably one or more selected from carbon black, graphene, and a graphene compound.

Abstract: An object is to achieve a manufacturing apparatus that can fully automate the manufacturing of a solid-state secondary battery. A mask alignment chamber, a first transfer chamber connected to the mask alignment chamber, a second transfer chamber connected to the first transfer chamber, a first film formation chamber connected to the second transfer chamber, a third transfer chamber connected to the first transfer chamber, and a second film formation chamber connected to the third transfer chamber are included.

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 provide a battery having excellent charge-discharge characteristics even in a low-temperature environment. The battery includes a positive electrode, a negative electrode, an electrolyte solution, and a separator. The electrolyte solution and the separator are included between the positive electrode and the negative electrode; the negative electrode includes a carbon material; and the electrolyte solution includes a lithium salt, a potassium salt, a fluorinated cyclic carbonate, a fluorinated linear carbonate, and at least one kind of anion. The carbon material includes graphite; the lithium salt includes LiPF6; the potassium salt includes KFSI; the fluorinated cyclic carbonate includes fluoroethylene carbonate; and the fluorinated linear carbonate includes methyl trifluoropropionate.

Abstract: A method for forming a positive electrode active material applicable to a lithium-ion battery having excellent charge and discharge characteristics even in a low-temperature environment is provided. The method for forming a positive electrode active material includes: a first step of heating lithium cobalt oxide with a median diameter of less than or equal to 10 ?m; a second step of mixing a fluorine source and a magnesium source with the lithium cobalt oxide subjected to the first step, thereby forming a first mixture; a third step of heating the first mixture; a fourth step of mixing a nickel source and an aluminum source with the first mixture subjected to the third step, thereby forming a second mixture; and a fifth step of heating the second mixture. The third step and the fifth step are performed in a state where the first mixture is held to have a thickness of less than or equal to 2.0 mm in a first setter.

Abstract: The relative position shifts of a positive electrode and a negative electrode occur owing to bending in charge or discharge, whereby uneven distribution is caused and potential varies. Not graphite but a lithium metal film is used as the negative electrode. A lithium metal film is formed over one side of the negative electrode current collector by an evaporation method or a sputtering method, and a laminated body is formed such that surfaces of two negative electrode current collectors where no film is formed are in contact with each other.

Abstract: An all-solid-state secondary battery having a higher level of safety than a conventional lithium-ion secondary battery using an electrolyte solution, specifically, a thin-film-type solid-state secondary battery, and a manufacturing method thereof are provided. As a solid electrolyte, a mixed material obtained by co-evaporation of SiO and an organic complex of lithium is used. That is, a solid electrolyte layer formed using a mixed material of an inorganic material and an organic material is used in a solid-state secondary battery. The ratio of oxygen to silicon in the solid electrolyte layer is higher than 1 and lower than 2.

Abstract: A safe charging environment with respect to a flexible battery capable of following the movement of a housing is provided. A flexible battery management system or an electronic device mounted with the flexible battery includes a sensor that senses a movement of the flexible battery and a charge control circuit having a function of starting charging or stopping charging of the flexible battery on the basis of a signal from the sensor; charging of the flexible battery is started using the charge control circuit when the sensor senses the flexible battery in a first mode where the flexible battery is opened and senses the flexible battery in a second mode where the flexible battery is curved.

Abstract: To provide a highly reliable power storage device. To provide a long-life power storage device. To provide a power storage device electrode having high adhesion with a current collector. To reduce or inhibit electrochemical decomposition of an electrolytic solution or the like on a surface of an electrode. The power storage device electrode includes a current collector and a second electrode layer provided over the current collector and including a second binder and an active material. A first electrode layer including a first binder and conductive particles is provided between the current collector and the second electrode layer. At least part of a surface of the active material is provided with a coating film, and the coating film is porous.

Abstract: A secondary battery that can inhibit degradation of an electrode is provided. A flexible secondary battery is provided. A flexible secondary battery includes a positive electrode, a negative electrode, and an exterior body surrounding the positive electrode and the negative electrode. The positive electrode includes a positive electrode current collector and a positive electrode active material layer provided over the positive electrode current collector. The negative electrode includes a negative electrode current collector and a negative electrode active material layer provided over the negative electrode current collector. One or both of the positive electrode current collector and the negative electrode current collector have rubber elasticity.

Abstract: A secondary battery that has flexibility and can inhibit degradation of a positive electrode lead connection portion or a negative electrode lead connection portion is provided.

Abstract: To provide a battery in which electrode distortion is suppressed in connecting an electrode terminal and a current collector exposed portion. The battery includes an electrode, an exterior body surrounding the electrode, and a lead extending from the inside to the outside of the exterior body. The electrode includes a current collector and an active material layer. The electrode includes a first region where the active material layer is provided over the current collector, and a second region where the current collector is exposed. The second region of the electrode includes a third region where the current collector is folded. The lead is connected to the electrode in the third region.

Abstract: A lithium ion battery having excellent discharge characteristics even at a temperature below freezing is provided. The lithium ion battery includes a positive electrode containing a positive electrode active material, an electrolyte solution, and a negative electrode containing a negative electrode active material that is a carbon material; the carbon material has peaks at 2? of greater than or equal to 20° and less than or equal to 24°, 2? of greater than or equal to 42° and less than or equal to 46.5°, and 2? of greater than or equal to 78° and less than or equal to 82° in X-ray diffraction (XRD) analysis; and a value of the discharge capacity obtained by subjecting the lithium ion battery to constant current and constant voltage charging (0.1 C, 4.5 V, and a termination current of 0.01 C) at 25° C. and then discharging at ?40° C. is higher than or equal to 40% of a value of the discharge capacity in discharging at 25° C.

Abstract: A secondary battery management system for achieving a secondary battery capable of being used even at low temperatures. The secondary battery management system includes a secondary battery that is charged and discharged at higher than or equal to ?50° C. and lower than or equal to 0° C., a first circuit having a function of measuring a voltage of the secondary battery, a second circuit having a function of measuring a current of the secondary battery, and a control circuit to which information on voltage from the first circuit or information on current from the second circuit is input. The control circuit starts charging to the secondary battery. The control circuit performs arithmetic operation of data showing battery characteristics on the basis of a value input from the first circuit or the second circuit. The control circuit detects a local maximum value of the data. The control circuit stops the charging when detecting the local maximum value.

Abstract: An all-solid-state secondary battery having a higher level of safety than a conventional lithium-ion secondary battery using an electrolyte solution, specifically, a thin-film-type solid-state secondary battery, and a manufacturing method thereof are provided. As a solid electrolyte, a mixed material obtained by co-evaporation of SiO and an organic complex of lithium is used. That is, a solid electrolyte layer formed using a mixed material of an inorganic material and an organic material is used in a solid-state secondary battery. The ratio of oxygen to silicon in the solid electrolyte layer is higher than 1 and lower than 2.

Abstract: A lithium ion battery having an excellent discharge characteristics even at temperatures below freezing is to be provided. The lithium ion battery includes a positive electrode including a positive electrode active material, an electrolyte, and a negative electrode including a negative electrode active material that is a carbon material. In the lithium ion battery, a value of discharge capacity obtained by, after performing constant current charging at a charge rate of 0.1 C (where 1 C=200 mA/g) until a voltage reaches 4.5 V and then performing constant voltage charging at 4.5 V until a current value achieves 0.01 C in an environment of 25° C., performing constant current discharging at a discharge rate of 0.1 C until a voltage reaches 2.5 V in an environment of ?40° C. is higher than or equal to 50% of a value of discharge capacity obtained by, after performing constant current charging at a charge rate of 0.1 C (where 1 C=200 mA/g) until a voltage reaches 4.

Abstract: A lithium-ion secondary battery with a high capacity and excellent charge and discharge cycle performance is provided. A secondary battery with a high capacity is provided. A secondary battery whose shape hardly changes in a vacuum is provided. A bendable secondary battery is provided. The secondary battery contains a positive electrode active material and an electrolyte; the positive electrode active material is lithium cobalt oxide to which magnesium is added; magnesium has a gradient in which a concentration increases from an inner portion toward a surface of the positive electrode active material; the electrolyte contains an imidazolium salt; and a temperature range where the secondary battery can operate is higher than or equal to ?20° C. and lower than or equal to 100° C.

Abstract: A battery in which a decrease in discharge capacity retention rate in charge and discharge cycle tests is inhibited is provided. The battery includes a positive electrode and a negative electrode. The positive electrode is used as a positive electrode of a test battery in which a negative electrode includes a lithium metal. When a test of 50 repetitions of a cycle of charge and discharge in which, after constant current charge is performed at a charge rate of 1 C (1 C=200 mA/g) until a voltage of 4.6 V is reached, constant voltage charge is performed at a voltage of 4.6 V until the charge rate reaches 0.1 C, and constant current discharge is then performed at a discharge rate of 1 C until a voltage of 2.5 V is reached is performed in a 25° C. environment or a 45° C. environment and discharge capacity is measured in each cycle, a discharge capacity value measured in a 50th cycle accounts for higher than or equal to 90% and lower than 100% of a maximum discharge capacity value in all 50 cycles.

Abstract: A power storage system with excellent characteristics is provided. A power storage system with a high degree of safety is provided. A power storage system with less deterioration is provided. A storage battery with excellent characteristics is provided. The power storage system includes a neural network and a storage battery. The neural network includes an input layer, an output layer, and one or more hidden layers between the input layer and the output layer. The predetermined hidden layer is connected to the previous hidden layer or the previous input layer by a predetermined weight coefficient, and connected to the next hidden layer or the next output layer by a predetermined weight coefficient. In the storage battery, voltage and time at which the voltage is obtained are measured as one of sets of data. The sets of data measured at different times are input to the input layer and the operational condition of the storage battery is changed in accordance with a signal output from the output layer.