Abstract: A lithium secondary battery characterized by a high power capacity and a long service life has a negative electrode 3, a positive electrode 2 and a non-aqueous electrolyte containing lithium salt. The lithium secondary battery is characterized by further comprising multiple oxide represented by a general formula Lix+aMn2−a−bMbQcO4+d (where M denotes at least one element selected from among Ni, Fe, Co, Cu and Cr; Q denotes at least one element selected from among C, N, S, P, Si, F, Cl, I and Br; and x, a, b, c and d are within the range of 0≦x≦) 1.1, 0≦a≦0.5, 0.05≦b≦1.0, 0.000001≦c<0.05 and 0≦d≦0.1, respectively) as a positive electrode activator.

Abstract: A lithium secondary battery having a longer life than conventional battery at a high temperature for electric power storage and electric vehicles is obtained. A lithium secondary battery having a long life at a high temperature can be obtained by using a material specified in Li/Mn atomic ratio, lattice constant, half value width, specific surface area, and average primary particle size as the positive electrode active material; and a material specified in density.

Abstract: Disclosed is a superconductor which has an aluminum area at the center of the cross section of the superconductor and a copper-covered multifilamentary NbTi composite conductor at the periphery parts of the cross section formed around the aluminum area, wherein the cross-sectional area ratio of (Cu+Al)/NbTi is in the range of 0.5 to 3.0 and the cross-sectional area ratio of Al/Cu is in the range of 0.05 to 0.5..

Abstract: In a forced flow cooling-type superconducting coil apparatus including a superconducting coil having superconducting wires inserted into a hollow conduit, current leads for supplying a current to said superconducting coil, and cooling means for cooling said superconducting wires by forcibly flowing the coolant through said hollow conduit, a part of the coolant flowing through said cooling means is branched to cool said current leads.