Abstract: To improve an impregnation property of an electrolyte and the cycle characteristics, which have been a problem in the case of employing a casing having a variable shape. A lithium secondary cell comprising a casing having a variable shape, and a cell element having a positive electrode, a negative electrode and an electrolyte, sealed in the casing, wherein a compound represented by following formula (1) is contained in the lithium secondary cell: A1-X-A2??(1) (wherein X is a Group VI element in the periodic table, and A1 and A2 represent an aromatic group, provided that A1 and A2 may be the same or different, and may be connected each other to constitute a ring.

Abstract: To increase safety against overcharging of a lithium secondary cell which uses a lithium-nickel compound oxide as a positive electrode active material. A lithium secondary cell comprises a casing (2,3) and a lithium secondary cell element (1) using a lithium-nickel compound oxide as a positive electrode active material, accommodated in the casing. The specific surface area of the lithium-nickel compound oxide is from 0.1 to 10 m2/g, and a surface area capacity ratio S/C, i.e. a ratio of a cell surface area S (cm2) to a cell capacity (mAh), is from 0.05 to 5.

Abstract: To improve an impregnation property of an electrolyte and the cycle characteristics, which have been a problem in the case of employing a casing having a variable shape.

Abstract: The present invention relates to a catalyst for polymerization of &agr;-olefin, which comprises: an essential component (A) of a transition metal compound, an essential component (B) of an ion exchangeable layer compound except for silicate, or an inorganic silicate, and an optional component (C) of an organoaluminum compound, said component (A) being represented by the general formula (I):

Abstract: Catalysts for polymerization of &agr;-olefin, composed of a transition metal compound, an inorganic silicate or an ion exchangeable layer compound other than silicate, and optionally an organoaluminum compound, are described.

Abstract: The present invention relates to a catalyst for polymerization of &agr;-olefin, which comprises:

Abstract: The present invention relates to a catalyst for polymerization of &agr;-olefin, which comprises: an essential component (A) of a transition metal compound, an essential component (B) of an ion exchangeable layer compound except for silicate, or an inorganic silicate, and an optional component (C) of an organoaluminum compound, said component (A) being represented by the general formula (I):

Abstract: A process for producing an .alpha.-olefin oligomer, comprising subjecting an .alpha.-olefin to oligomerization in a reaction solution containing a chromium-based catalyst produced by bringing at least a chromium compound (a), a pyrrole ring-containing compound (b), an alkyl aluminum compound (c) and a halogen-containing compound (d) into contact with each other, wherein the chromium-based catalyst is a catalyst produced by bringing the pyrrole ring-containing compound (b), the alkyl aluminum compound (c) and the halogen-containing compound (d) into contact with each other in a hydrocarbon and/or halogenated hydrocarbon solvent, and then bringing the resultant mixed solution into contact with the chromium compound (a); or a catalyst produced by bringing the chromium compound (a), the pyrrole ring-containing compound (b), the alkyl aluminum compound (c) and the halogen-containing compound (d) into contact with each other in a hydrocarbon and/or halogenated hydrocarbon solvent in the absence of .alpha.

Abstract: The disclosure described a process for producing an .alpha.-olefin oligomer, which comprises carrying out oligomerization of an .alpha.-olefin in a solvent in the presence of a catalytically effective amount of a chromium-based catalyst system composed of a combination of at least (a) a chromium compound, (b) a nitrogen-containing compound of at least one selected from the group consisting of an amine, an amide and an imide, (c) an alkylaluminum compound and (d) a halogen-containing compound,wherein each of the .alpha.-olefin, the chromium compound (a), the nitrogen-containing compound (b) of at least one selected from the group consisting of an amine, an amide and an imide, the alkylaluminum compound (c) and the halogen-containing compound (d) is supplied to a reaction system in a mode that the chromium compound (a) and the alkylaluminum compound (c) do not contact each other before each of said compounds (a) to (d) and the .alpha.-olefin coexists in the reaction solvent and the oligomerization of an .alpha.

Abstract: The disclosure describes a process for preparing .alpha.-olefin oligomers, which comprises carrying out oligomerization of an .alpha.-olefin in a solvent by reacting said .alpha.-olefin in a chromium-based catalyst system composed of a combination of at least a chromium compound, an amine or metal amide, and an alkylaluminum compound, in a contacting mode that the chromium compound and the alkylaluminum compound are not previously contacted with each other.

Abstract: An oligomerization of .alpha.-olefins is carried out in a solvent using a chromium-based catalyst system comprising at least (a) a chromium compound, (b) at least one nitrogen-containing compound selected from amines, amides and imides, and (c) an alkylaluminum compound, and the catalyst components and by-product polymers are recovered simultaneously from the reaction solution. Such process is an industrially advantageous process for producing .alpha.-olefin oligomers by using a chromium-based catalyst, and is simple and capable of efficiently recovering the by-product polymers and the catalyst components simultaneously.