Abstract: A nonaqueous secondary battery electrolyte solution for use in a nonaqueous secondary battery comprising vanadium sulfide as a cathode active material and a lithium-containing compound as an anode active material, the nonaqueous secondary battery electrolyte solution comprising lithium bis(fluorosulfonyl)imide (LiFSI), cyclic carbonates, and a hydrofluoroether (HFE).

Abstract: A foreign element-containing vanadium sulfide contains, as constituent elements, vanadium, sulfur, and a foreign element, wherein the compositional ratio of the foreign element to the vanadium (M1/V) is in the range of 0.05 to 1.5 in terms of molar ratio; the compositional ratio of the sulfur to the vanadium (S/V) is in the range of 3.0 to 10.0 in terms of molar ratio; and the foreign element includes at least one member selected from the group consisting of Nb, Ti, Zr, Mo, Sc, and Y, or includes at least one member selected from the group consisting of Li, B, N, O, F, Mg, S, Cl, Ca, Br, Sr, Sc, I, Fe, Co, Ni, Zn, Y, Mo, Tc, and Cd. The foreign element-containing vanadium sulfide is an electrode active material for a lithium ion secondary battery that exhibits satisfactorily high initial capacity and that provides improved electrochemical performance or cycle performance.

Abstract: An electrolyte solution that satisfies at least one of the following (A) and (B) can improve the charge/discharge cycle performances of nonaqueous secondary batteries containing a lithium-free transition metal sulfide as a cathode active material and can also improve initial coulombic efficiency when a specific additive is used: (A) the nonaqueous secondary battery electrolyte solution contains an organic solvent containing a cyclic carbonate compound, and the content of the cyclic carbonate compound is 80 to 100 vol %, and the content of a chain carbonate compound is 0 to 20 vol %, based on the total amount of the organic solvent taken as 100 vol %; and (B) the nonaqueous secondary battery electrolyte solution contains an organic solvent containing a cyclic carbonate compound and an additive.

Abstract: The present invention provides coated metal sulfide particles comprising a metal sulfide that is partially or totally coated with a coating layer containing a metal oxide, the metal sulfide having a composition ratio of sulfur to a metal (S/M1) of 2.1 to 10 in terms of the molar ratio. The coated metal sulfide particles are a material that improves charge-and-discharge cycle characteristics without reducing the initial capacity.

Abstract: An electrode active material for lithium-ion secondary batteries that has a sufficiently high initial capacity, improved charge-and-discharge cycle characteristics, and improved coulombic efficiency in the mid-term charge-and-discharge cycles can be obtained by a phosphorus-containing low-crystalline vanadium sulfide comprising vanadium, phosphorus, and sulfur as constituent elements, the composition ratio of the phosphorus to the vanadium (P/V) being 0.1 to 1.0 in terms of the molar ratio, the composition ratio of the sulfur to the vanadium (S/V) being 4.00 to 10.00 in terms of the molar ratio.

Abstract: By using a potassium ion secondary battery positive electrode active material comprising a potassium compound represented by general formula (1): KnMOm, wherein M is copper or iron, n is 0.5 to 3.5, and m is 1.5 to 2.5, provided is a potassium ion secondary battery positive electrode active material having higher theoretical discharge capacity and higher effective capacity than a potassium secondary battery using Prussian blue as a positive electrode active material.

Abstract: Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1): KnAkBOm, wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

Abstract: A composite containing phosphorus, lithium, iron, sulfur, and carbon as constituent elements wherein lithium sulfide (Li2S) is present in an amount of 90 mol % or more, and wherein the crystallite size calculated from the half-width of a diffraction peak based on the (111) plane of Li2S as determined by X-ray powder diffraction measurement is 80 nm or less. The composite exhibits a high capacity (in particular, a high discharge capacity) useful as an electrode active material for a lithium-ion secondary battery (in particular, a cathode active material for a lithium-ion secondary battery), without the need for stepwise pre-cycling treatment.

Abstract: The main object is to provide a novel material with excellent charge and discharge characteristics, such as a high utilization rate of a positive electrode, a high capacity, and good cycle characteristic, in which the material is a compound containing as the major component lithium sulfide useful as a cathode active material for lithium secondary batteries. The invention provides a lithium sulfide-iron-carbon composite containing lithium, iron, sulfur and carbon as constituent elements, with lithium sulfide (Li2S), as the main phase, having a crystallite size of 50 nm or less as calculated from the half width of the diffraction peak based on the (111) plane of Li2S as determined by X-ray powder diffraction.

Abstract: The sulfide of the present invention comprises an amorphous (lithium) niobium sulfide having an average composition represented by formula (1): Lik1NbSn1 (wherein 0?k1?5; 3?n1?10; and when n1?3.5, k1?0.5), or an amorphous (lithium) titanium niobium sulfide having an average composition represented by formula (2): Lik2Ti1-m2Nbm2Sn2 (wherein 0?k2?5; 0<m2<1; 2?n2?10; and when n2?3.5, k2?1.5). The sulfide of the present invention is a material that is useful as a cathode active material for lithium batteries, such as lithium primary batteries, lithium secondary batteries, and lithium ion secondary batteries, and has a high charge-discharge capacity, high electrical conductivity, and excellent charge-discharge performance.

Abstract: By using a potassium ion secondary battery positive electrode active material comprising a potassium compound represented by general formula (1): KnMm, wherein M is copper or iron, n is 0.5 to 3.5, and m is 1.5 to 2.5, provided is a potassium ion secondary battery positive electrode active material having higher theoretical discharge capacity and higher effective capacity than a potassium secondary battery using Prussian blue as a positive electrode active material.

Abstract: Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1): KnAkBOm, wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

Abstract: The present invention provides a novel lithium titanium sulfide, lithium niobium sulfide, or lithium titanium niobium sulfide that contains a sulfide containing lithium, titanium and/or niobium, and sulfur as constituent elements, and that has excellent charge-discharge performance (especially excellent charge-discharge capacity and charge-discharge potential) useful as a cathode active material or the like for lithium batteries, such as metal lithium secondary batteries or lithium-ion secondary batteries.

Abstract: A composite containing phosphorus, lithium, iron, sulfur, and carbon as constituent elements wherein lithium sulfide (Li2S) is present in an amount of 90 mol % or more, and wherein the crystallite size calculated from the half-width of a diffraction peak based on the (111) plane of Li2S as determined by X-ray powder diffraction measurement is 80 nm or less. The composite exhibits a high capacity (in particular, a high discharge capacity) useful as an electrode active material for a lithium-ion secondary battery (in particular, a cathode active material for a lithium-ion secondary battery), without the need for stepwise pre-cycling treatment.

Abstract: The sulfide of the present invention comprises an amorphous (lithium) niobium sulfide having an average composition represented by formula (1): Lik1NbSn1 (wherein 0?k1?5; 3?n1?10; and when n1?3.5, k1?0.5), or an amorphous (lithium) titanium niobium sulfide having an average composition represented by formula (2): Lik2Ti1-m2Nbm2Sn2 (wherein 0?k2?5; 0<m2<1; 2?n2?10; and when n2?3.5, k2?1.5). The sulfide of the present invention is a material that is useful as a cathode active material for lithium batteries, such as lithium primary batteries, lithium secondary batteries, and lithium ion secondary batteries, and has a high charge-discharge capacity, high electrical conductivity, and excellent charge-discharge performance.

Abstract: The present invention provides a novel lithium titanium sulfide, lithium niobium sulfide, or lithium titanium niobium sulfide that contains a sulfide containing lithium, titanium and/or niobium, and sulfur as constituent elements, and that has excellent charge-discharge performance (especially excellent charge-discharge capacity and charge-discharge potential) useful as a cathode active material or the like for lithium batteries, such as metal lithium secondary batteries or lithium-ion secondary batteries.

Abstract: The main object is to provide a novel material with excellent charge and discharge characteristics, such as a high utilization rate of a positive electrode, a high capacity, and good cycle characteristic, in which the material is a compound containing as the major component lithium sulfide useful as a cathode active material for lithium secondary batteries. The invention provides a lithium sulfide-iron-carbon composite containing lithium, iron, sulfur and carbon as constituent elements, with lithium sulfide (Li2S), as the main phase, having a crystallite size of 50 nm or less as calculated from the half width of the diffraction peak based on the (111) plane of Li2S as determined by X-ray powder diffraction.

Abstract: The present invention provides a process for producing a lithium sulfide-carbon composite, the process comprising placing a mixture of lithium sulfide and a carbon material having a specific surface area of 60 m2/g or more in an electrically-conductive mold in a non-oxidizing atmosphere, and applying a pulsed direct current to the mold while pressurizing the mixture in a non-oxidizing atmosphere, thereby subjecting the lithium sulfide and the carbon material to heating reaction; and a lithium sulfide-carbon composite obtained by this process, the composite having a carbon content of 15 to 70 weight %, and a tap density of 0.4 g/cm3 or more when the carbon content is 30 weight % or more, or a tap density of 0.5 g/cm3 or more when the carbon content is less than 30 weight %.

Abstract: The present invention provides a process for producing a composite of metal sulfide and metal oxide obtained by dispersing a metal sulfide, which is nickel sulfide, copper sulfide, iron sulfide or a mixture thereof, in a metal salt-containing aqueous solution, and depositing metal salt on the metal sulfide by drying the aqueous solution; and heat-treating the metal sulfide comprising a metal salt deposited thereon at 400 to 900° C. in a sulfur-containing atmosphere. Also disclosed is a composite obtained by the aforementioned process, comprising a metal sulfide having a surface partially covered with a metal oxide. The composite of the present invention has improved cycle characteristics while maintaining a high charge/discharge capacity and excellent electrical conductivity inherently possessed by metal sulfide, which is usable as a material having a high theoretical capacity and excellent electrical conductivity when used as a positive-electrode material for a lithium secondary battery.

Abstract: The present invention provides a production process of a metal sulfide, which includes placing a metal component and sulfur in a conductive container, and applying a pulsed direct current to the container in a non-oxidizing atmosphere to cause the metal component to react with sulfur, and also provides a metal sulfide obtained by the process and represented by a composition formula: MSx, wherein M is at least one member selected from the group consisting of Ni, Cu, Fe, and Co, and 1<x?2. The present invention is capable of easily producing a metal sulfide with a high proportion of sulfur atoms, which is expected to exhibit excellent properties as a positive-electrode active material for a high capacity lithium secondary battery.