Abstract: An aspect of the present invention relates to a negative electrode for a sodium molten salt battery, the negative electrode including a negative electrode current collector and a negative electrode mixture layer arranged on a surface of the negative electrode current collector, the negative electrode mixture layer including negative electrode active material particles and a film arranged on a surface of each of the negative electrode active material particles, the negative electrode active material particles containing hard carbon, and the film containing a sodium-containing sulfide.

Abstract: A molten salt battery is provided which includes a positive electrode including a positive-electrode active material represented by the general formula: An(1?x)M1nxFe1?yM2yP2O7 (wherein n is 1 or 2, 0?x?0.5, 0?y?0.5, A is an alkali metal element, M1 is an element other than the element A, M2 is an element other than Fe), a negative electrode including a negative-electrode active material, a separator interposed between the positive electrode and the negative electrode, and a molten salt electrolyte. The molten salt electrolyte contains 90% by mass or more of an ionic liquid containing a salt of the element A.

Abstract: Provided is a sodium molten-salt battery having good charge-discharge cycle characteristics. The sodium molten-salt battery includes a positive electrode that contains a positive electrode active material, a negative electrode that contains a negative electrode active material, and a molten-salt electrolyte that contains a sodium salt and an ionic liquid that dissolves the sodium salt. The negative electrode active material contains non-graphitizable carbon. The ionic liquid is a salt of a bis(sulfonyl)imide anion and a first onium cation that does not cause a Faradaic reaction with the non-graphitizable carbon. The molten-salt electrolyte contains a second onium cation in an amount of 1,000 ppm by mass or less. The second onium cation is represented by a general formula (1): R1R2R3R4N+ where R1 to R4 are each independently a hydrogen atom or a methyl group.

Abstract: Provided is a sodium molten-salt battery having good storage characteristics and good charge-discharge cycle characteristics. The sodium molten-salt battery includes a positive electrode that contains a positive electrode active material, a negative electrode that contains a negative electrode active material, and a molten-salt electrolyte that contains a sodium salt and an ionic liquid that dissolves the sodium salt. The ionic liquid contains a salt of an anion and a pyrrolidinium cation having, at the 1-position, a methyl group and an alkyl group having 2 to 5 carbon atoms. A content of 1-methylpyrrolidine in the molten-salt electrolyte is 100 ppm by mass or less.

Abstract: Provided are a molten-salt electrolyte having good charge-discharge cycle characteristics and a sodium molten-salt battery using the same. The molten-salt electrolyte contains an ionic liquid whose ultraviolet-visible absorption spectrum does not have an absorption peak attributable to impurities in a wavelength range of 200 to 500 nm, and a sodium salt. The sodium molten-salt battery includes a positive electrode that contains a positive electrode active material, a negative electrode that contains a negative electrode active material, and the molten-salt electrolyte. The ionic liquid is preferably a salt of an organic onium cation and a bis(sulfonyl)imide anion.

Abstract: A positive electrode active material for sodium molten salt batteries includes a sodium-containing metal oxide that can electrochemically intercalate and deintercalate sodium ions, wherein a ratio by mass of sodium carbonate is 500 ppm or less. A ratio by mass of sodium carbonate in the positive electrode active material is more preferably 100 ppm or less.

Abstract: Provided is an electrode for a sodium molten-salt battery in which degradation of the electrode can be suppressed even when charging and discharging are repeated, and which has excellent cycle characteristics. The electrode for a sodium molten-salt battery includes a current collector and an electrode mixture adhering to a surface of the current collector, in which the electrode mixture includes an electrode active material and a binder containing a polymer, and the polymer does not contain a fluorine atom. The polymer can include, for example, at least one selected from the group consisting of polyamide resins and polyimide resins or at least one selected from the group consisting of acrylic resins, rubber-like polymers, and cellulose derivatives.

Abstract: A molten salt battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the electrolyte includes a molten salt, the molten salt contains at least sodium ions, and the moisture content We1 in the molten salt is 300 ppm or less in terms of mass ratio.

Abstract: The present invention relates to a sodium secondary battery comprising a positive electrode which includes a positive electrode current collector and a positive electrode material, the positive electrode material being carried on the positive electrode current collector, wherein the positive electrode material comprises a positive electrode active material reversibly containing sodium cation; a negative electrode which includes a negative electrode current collector and a negative electrode material, the negative electrode material being carried on the negative electrode current collector, wherein the negative electrode material comprises a negative electrode active material reversibly containing sodium cation; an electrolyte interposed at least between the positive electrode and the negative electrode; and a separator for retaining the electrolyte and separating the positive electrode and the negative electrode from each other; wherein the negative electrode active material is amorphous carbon, and the elect

Abstract: A heat resistant battery includes a positive electrode including a positive electrode current collector and a positive electrode active material fixed on the positive electrode current collector, wherein the positive electrode active material includes a sodium-containing transition metal compound capable of electrochemically storing and releasing a sodium ion; a negative electrode including a negative electrode current collector and a negative electrode active material fixed on the negative electrode current collector, wherein the negative electrode active material contains at least one selected from the group consisting of a sodium-containing titanium compound and a non-graphitizable carbon, each of the sodium-containing titanium compound and the non-graphitizable carbon capable of storing and releasing a sodium ion at a lower potential than a potential of the sodium-containing transition metal compound; and a sodium ion-conductive electrolyte provided at least between the positive electrode and the negative

Abstract: As a molten salt composition lacking a clear melting point and including a molten salt that can be suitably used as an electrolytic solution of a secondary battery, there is provided a molten salt composition including a mixture of two or more kinds of molten salts which can be used as an electrolytic solution of a secondary battery. Particularly, provided is a molten salt composition comprising two kinds of molten salts each having cations with ion diameters different from each other, composition ratio being set to a composition ratio within a range in which the molten salt composition lacks a melting point. Also provided is a secondary battery including the molten salt composition as an electrolytic solution, which can maintains an available state even when the temperature becomes low without rapidly becoming unavailable.

Abstract: A material design of a molten salt battery which is suitable for a temperature range in which the battery is used is shown, and a molten salt battery applicable even under a severe environment where vibrations are given is provided. In the molten salt battery according to the present invention, the operating temperature range of 25° C. to 300° C. is divided into ranges of 25° C. to 120° C., 80° C. to 140° C. and 140° C. to 300° C., and for each temperature range, a material that is a choice is defined for each of an outer package, a binder, an anode active material and a separator as well as an electrolytic solution. Further, the molten salt battery includes a vibration controlling portion for reducing vibrations given to the outer package. As for the electrolytic solution, for example, an electrolytic solution containing an organic cation and FSA as an anion, or NaFSA is suitable for the range of 25° C. to 120° C.

Abstract: Provided is a power supply system capable of being used in a well over a long period of time. A power supply system for a well according to the present invention includes a secondary battery having an operating temperature range including a temperature of the inside of a well and supplying power to a device installed in the well; and a charge-discharge mechanism for charging and discharging the secondary battery, and is installed in the well. The secondary battery to be used in the power supply system may be a molten salt battery, and may include a sensor and communication apparatus.

Abstract: Provided is a method for operating a molten salt battery having a sodium compound (NaCrO2) in a positive electrode and tin (Sn) in a negative electrode with a molten salt as an electrolytic solution. Although the operating temperature range of the molten salt battery is originally from 57° C. to 190° C., the molten salt battery is operated with an internal temperature thereof (temperature of electrodes and molten salt) set at from 98° C. to 190° C. to cause sodium to turn to a liquid phase. The sodium penetrates into a Sn—Na alloy micronized in the negative electrode, so that separation of the Sn—Na alloy is suppressed.