A solid electrolyte includes an ion conductor represented by at least one of Formulae 1 to 3,
Li.sub.1+3xM1.sub.1−xO.sub.2  Formula 1
wherein, in Formula 1, M1 is a trivalent element, and 0<x<1,
L.sub.1−yM2O.sub.2−yX.sub.y  Formula 2
wherein, in Formula 2, M2 is a trivalent element, X is at least one of a halogen atom or a pseudohalogen, and 0<y<1,
Li.sub.1−z(a−3)M3.sub.1−zD.sub.zO.sub.2  Formula 3
wherein, in Formula 3, M3 is a trivalent element, D is at least one of a monovalent element to a hexavalent element, and 0<z<1.

A solid electrolyte includes an ion conductor represented by at least one of Formulae 1 to 3,
Li.sub.1+3xM1.sub.1−xO.sub.2  Formula 1
wherein, in Formula 1, M1 is a trivalent element, and 0<x<1,
L.sub.1−yM2O.sub.2−yX.sub.y  Formula 2
wherein, in Formula 2, M2 is a trivalent element, X is at least one of a halogen atom or a pseudohalogen, and 0<y<1,
Li.sub.1−z(a−3)M3.sub.1−zD.sub.zO.sub.2  Formula 3
wherein, in Formula 3, M3 is a trivalent element, D is at least one of a monovalent element to a hexavalent element, and 0<z<1.

One aspect of the present invention is a positive active material that contains an oxide containing lithium, a transition metal element and a typical element, and having an antifluorite crystal structure, in which the transition metal element is cobalt, iron, copper, manganese, nickel, chromium, or a combination thereof, the typical element is a group 13 element, a group 14 element, phosphorus, antimony, bismuth, tellurium or a combination thereof, and a molar ratio of a content of the typical element to a total content of the transition metal element and the typical element in the oxide is more than 0.05 and 0.5 or less.

One aspect of the present invention is a positive active material that contains an oxide containing lithium, a transition metal element and a typical element, and having an antifluorite crystal structure, in which the transition metal element is cobalt, iron, copper, manganese, nickel, chromium, or a combination thereof, the typical element is a group 13 element, a group 14 element, phosphorus, antimony, bismuth, tellurium or a combination thereof, and a molar ratio of a content of the typical element to a total content of the transition metal element and the typical element in the oxide is more than 0.05 and 0.5 or less.

The present invention provides a secondary battery-use active material that allows for an improvement in thermal stability after charge and discharge are repeated. The secondary battery-use active material of the present invention includes a cathode active material that includes (A) a main phase and a sub-phase, (B) the main phase containing a first lithium compound represented by Li.sub.aNi.sub.bM.sub.cAl.sub.dO.sub.e (where M is an element such as cobalt, and 0.8<a<1.2, 0.45≦b≦1, 0≦c≦1, 0≦d≦0.2, 0<e≦1.98, (c+d)>0, and (b+c+d)≦1), and (C) the sub-phase containing a second lithium compound that contains lithium, aluminum, and oxygen as constituent elements.

The present invention relates to a positive active material and a method for producing same and, more specifically, to a positive active material comprising LiAlO2 at the surface thereof as a result of reacting an Al compound with residual lithium and to a method for producing same.

The present invention relates to heterogeneous acid catalysts comprising or consisting of mixed metal salts, of lithium and aluminum phosphates and sulfates, and combinations with metallic cations, such as magnesium, titanium, zinc, zirconium and gallium, to provide adequate Lewis acidity; organic or inorganic porosity promoters, such as polysaccharides; and agglomerates, such as clays, kaolin and metal oxides of the type M.sub.xO.sub.y, where; M=Al, Mg, Sr, Zr or Ti, and other metals of groups IA, IIA and IVB, x=1 or 2 and y=2 or 3, for the formation of particles. A process is disclosed for obtaining from the catalyst by the hydrolysis of aluminum lithium hydride with water and oxygenated solvent, such as an ether. The catalysts are used in batch reactor and continuous flow systems in reactions that require moderate Lewis acidity, such as refining, petrochemical and general chemistry, including the transesterification of glycerides to produce alkyl esters.

The purpose of the present invention is to provide an industrially advantageous method for producing α-lithium aluminate which has physical properties that are suitable for use as an electrolyte holding plate of a MCFC having excellent thermal stability, even if the α-lithium aluminate is a fine material having a BET specific surface area of 10 m.sup.2/g or higher in particular. Provided is a method for producing α-lithium aluminate characterized by subjecting a mixture (a), which is obtained by mixing transitional alumina and lithium carbonate at an Al/Li molar ratio of 0.95-1.01, to a first firing reaction so as to obtain a fired product, and subjecting a mixture (b), which is obtained by adding an aluminum compound to the obtained fired product at quantities whereby the molar ratio of aluminum atoms in the aluminum compound relative to lithium atoms in the fired product (Al/Li) is 0.001-0.05, to a second firing reaction.

A precursor solution according to the present disclosure contains an organic solvent, a lithium oxoacid salt that shows solubility in the organic solvent, and an aluminum compound that shows solubility in the organic solvent. When a ratio between a content of aluminum and a content of lithium in a case of satisfying a stoichiometric formulation of the following compositional formula (1) is set as a reference, the content of lithium in the precursor solution is preferably 1.00 times or more and 1.20 times or less with respect to the reference.

LiAlO.sub.2  (1)

The present invention relates to a cathode additive, a method for preparing the same, and a cathode and a lithium secondary battery including the same. More specifically, one embodiment of the present invention provides a cathode additive that can offset an irreversible capacity imbalance, increase the initial charge capacity of a cathode, and simultaneously inhibit the generation of gas in a battery.