Abstract: A control system for a secondary battery which is less affected by the ambient temperature by performing temperature control of the secondary battery is provided. A control system for a secondary battery which is less affected by the ambient temperature and in which a plurality of kinds of secondary batteries are used for temperature control is achieved and mounted on a vehicle. Specifically, when the ambient temperature is low, some of second secondary batteries are heated by self-heating of a first secondary battery. After the second secondary batteries are sufficiently heated, the rest of the second secondary batteries are heated in stages by self-heating of the some of the second secondary batteries whose temperature has been increased.

Abstract: A light-emitting element includes a light-emitting layer including a guest, an n-type host and a p-type host between a pair of electrodes, where the difference between the energy difference between a triplet excited state and a ground state of the n-type host (or p-type host) and the energy difference between a triplet excited state and a ground state of the guest is 0.15 eV or more. Alternatively, in such a light-emitting element, the LUMO level of the n-type host is higher than the LUMO level of the guest by 0.1 eV or more, or the HOMO level of the p-type host is lower than the HOMO level of the guest by 0.1 eV or more.

Abstract: A positive electrode active material with little deterioration is provided. Positive electrode active material particles with little deterioration are provided. A power storage device with little deterioration is provided. A highly safe power storage device is provided. A novel power storage device is provided. A secondary battery includes a positive electrode and a negative electrode.

Abstract: Secondary batteries using lithium cobalt oxide as positive electrode active materials have a problem of a decrease in battery capacity due to repeated charging/discharging, for example. A positive electrode active material particle which hardly deteriorates is provided. In a first step, a container in which a lithium oxide and a fluoride are set is placed in a heating furnace, and in a second step, the inside of the heating furnace is heated in an atmosphere containing oxygen. The heating temperature of the second step is from 750° C. to 950° C., inclusive. By the manufacturing method, fluorine can be contained in the positive electrode active material particle to increase the wettability of the surface of the positive electrode active material so that the surface of the positive electrode active material is homogenized and planarized. The crystal structure of the thus manufactured positive electrode active material is unlikely to be broken in repeated high-voltage charging/discharging.

Abstract: A secondary battery with excellent cycle performance is provided. The secondary battery is an all-solid-state battery including a positive electrode current collector layer, a base film, a positive electrode active material layer, a buffer layer, and a solid electrolyte layer. The base film contains titanium nitride. The positive electrode active material layer contains lithium cobalt oxide. The buffer layer contains titanium oxide. The solid electrolyte layer contains a titanium compound. By using titanium oxide for the buffer layer, a side reaction between the positive electrode active material layer and the solid electrolyte layer can be suppressed, and cycle performance can be improved.

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: Provided is a light-emitting element with high emission efficiency including a fluorescent material as a light-emitting substance. In a light-emitting element including a pair of electrodes and an EL layer between the pair of electrodes, a delayed fluorescence component due to triplet-triplet annihilation accounts for 20% or more of light emitted from the EL layer, and the light has at least one emission spectrum peak in the blue wavelength range. The EL layer includes an organic compound in which an energy difference between the lowest singlet excited energy level and the lowest triplet excited energy level is 0.5 eV or more. The EL layer includes a benzo[a]anthracene compound.

Abstract: A secondary battery that can withstand at least high temperature is achieved by designing the structure of the secondary battery. The secondary battery uses: a positive electrode active material obtained by a formation method including a first step of forming a first mixture by pulverizing magnesium fluoride, lithium fluoride, a nickel source, and an aluminum source and then mixing the pulverized materials with powder of lithium cobalt oxide, and a second step of forming a second mixture by heating the first mixture at a temperature lower than an upper temperature limit of the lithium cobalt oxide; and an electrolyte solution to which LiBOB is added.

Abstract: A light-emitting device with low driving voltage and favorable reliability is provided. The light-emitting device includes an electron-injection layer between a cathode and a light-emitting layer. The electron-injection layer is a mixed film of a metal and an organic compound having a function of interacting with the metal as a tridentate or tetradentate ligand, and the metal atom and the organic compound form SOMO.

Abstract: A light-emitting element includes a light-emitting layer including a guest, an n-type host and a p-type host between a pair of electrodes, where the difference between the energy difference between a triplet excited state and a ground state of the n-type host (or p-type host) and the energy difference between a triplet excited state and a ground state of the guest is 0.15 eV or more. Alternatively, in such a light-emitting element, the LUMO level of the n-type host is higher than the LUMO level of the guest by 0.1 eV or more, or the HOMO level of the p-type host is lower than the HOMO level of the guest by 0.1 eV or more.

Abstract: A highly reliable solid-state secondary battery with improved cycle performance, reliability, or safety is provided. A negative electrode includes, over a negative electrode current collector, n negative electrode active material layers (n is an integer greater than or equal to 2) and n?1 separation layers. The negative electrode active material layers and the separation layers are alternately stacked. The thickness of the negative electrode active material is greater than or equal to 20 nm and less than or equal to 100 nm. The separation layers each include titanium. The separation layer preferably includes titanium (Ti), titanium nitride (TiN), or titanium oxynitride (TiOxNy, 0<x<2, 0<y<1). With the negative electrode having such a structure, the expansion of each negative electrode active material layer can be reduced. Accordingly, the negative electrode that has high capacity and hardly causes a crack or a breakage can be obtained.

Abstract: A light-emitting device with low driving voltage and favorable reliability is provided. The light-emitting device includes an electron-injection layer between a cathode and a light-emitting layer. The electron-injection layer is a mixed film of a metal and an organic compound having a function of interacting with the metal as a tridentate or tetradentate ligand, and the metal atom and the organic compound form SOMO.

Abstract: A quinoxaline derivative that is a novel organic compound is provided. A quinoxaline derivative represented by General Formula (G1) has a structure in which a quinoxaline skeleton is bonded to the 9-position of an anthracene skeleton, the 10-position of the anthracene skeleton is bonded to a heteroaromatic ring, and the 3-position of the heteroaromatic ring is nitrogen. In General Formula (G1) shown above, a and b each independently represent a substituted or unsubstituted arylene group having 6 to 13 carbon atoms in a ring. In addition, m and n are each independently 0, 1, or 2.

Abstract: A novel light-emitting device that is highly convenient, useful, or reliable is provided. An organic compound in which a substituted or unsubstituted naphtho[2,3-c]carbazolyl group or a substituted or unsubstituted benzo[c]naphtho[2,3-g]carbazolyl group is bonded to a substituted or unsubstituted 9H-carbazolyl group or a substituted or unsubstituted anthryl group through a substituted or unsubstituted arylene group. The arylene group has 6 to 13, inclusive, carbon atoms.

Abstract: A light-emitting device having a long lifetime is provided. In a light-emitting device that includes an EL layer between a pair of electrodes, the carrier balance is controlled with a hole-injection layer and an electron-transport layer of the EL layer having certain structures, so that the carrier balance spontaneously changes during driving and the initial degradation of the light-emitting device is inhibited. In addition, at this time, the rate of the spontaneous change is low when an electron-injection barrier at the interface between a light-emitting layer and the electron-transport layer of the EL layer which are stacked is high; thus, it is possible to obtain a light-emitting device which is excellent in terms of long-term degradation.

Abstract: A light-emitting device material with a low refractive index is provided. The light-emitting device material contains an organic compound which has a pyridine skeleton, a diazine skeleton, or a triazine skeleton and in which the proportion of carbon atoms forming a bond by sp3 hybrid orbitals is within a certain range. The light-emitting device material contains an organic compound including at least one six-membered heteroaromatic ring having 1 to 3 nitrogen atoms and a plurality of aromatic hydrocarbon rings each having 6 to 14 carbon atoms in a ring. At least two of the plurality of aromatic hydrocarbon rings are benzene rings. The organic compound has a plurality of hydrocarbon groups forming a bond by the sp3 hybrid orbitals. The ordinary refractive index of a layer containing the organic compound with respect to light with a wavelength in the range from 455 nm to 465 nm is 1.5 to 1.75.

Abstract: A material that can be used in a wide temperature range is provided. A graphene compound includes graphene or graphene oxide and a substituted or unsubstituted chain group, the chain group includes two or more ether bonds, and the chain group is bonded to the above graphene or graphene oxide through a Si atom. Alternatively, a method for forming a graphene compound includes a first step and a second step after the first step. In the first step, graphene oxide and a base are stirred under a nitrogen stream. In the second step, the mixture is cooled to room temperature, a silylating agent that has a group having two or more ether bonds is introduced into the mixture, and the obtained mixture is stirred. The base is butylamine, pentylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, tripropylamine, or pyridine.

Abstract: A novel compound for a host material is provided. A compound for a host material that is capable of increasing the lifetime of a light-emitting device is provided. A light-emitting device with a long lifetime is provided. A material whose thermophysical properties such as a glass transition temperature are high is provided. An anthracene compound for a host material represented by General Formula (G1) below is provided. (Note that in General Formula (G1), R1 to R7 each independently represent hydrogen or an aryl group having 1 to 25 carbon atoms.

Abstract: A novel organic compound represented by General Formula (G1) is provided. In General Formula (G1), X1 and X2 each independently represent a secondary or tertiary alkyl group having 3 to 6 carbon atoms and having a branched carbon atom which is bonded to a phenyl group. In addition, Ar1 represents a substituted or unsubstituted condensed aromatic ring skeleton having 10 to 60 carbon atoms and composed of two or more rings or a substituted or unsubstituted condensed heteroaromatic ring skeleton having 8 to 60 carbon atoms and composed of two or more rings. Furthermore, Ar2 represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Moreover, n represents any of 1 to 3, and in the case where n is 2 or more, two or more groups bonded to Ar1 may be identical or different.

Abstract: A novel organic compound with favorable thermophysical properties is provided. An organic compound represented by General Formula (G1) is provided. At least one of X1 to X5 is a secondary or tertiary alkyl group having 3 to 6 carbon atoms in which a carbon atom bonded to a phenyl group branches. Each of R1 to R7 is independently any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and an unsubstituted or alkyl-substituted aryl group having 6 to 13 carbon atoms. Ar1 represents a substituted or unsubstituted condensed heteroaromatic ring skeleton having 8 to 60 carbon atoms and composed of two or more aromatic rings, and Ar2 represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Furthermore, n is any of 1 to 3.