Abstract: [Problem to be Solved] To provide a vanadium active material solution which has a vanadium active material concentration of 2.5 M or more in a sulfuric acid solution including a dispersoid (suspensible material), can stably maintain high energy density based on the concentration, and can respond also to fast charge and discharge, and to provide a vanadium redox battery using the active material solution. [Solution] The above problem is solved by a vanadium active material solution comprising a vanadium compound, which is an active material, as a solute and a dispersoid, wherein the total concentration of vanadium is 2.5 M or more. Here, in a negative electrolyte, the vanadium compound comprises one or both of bivalent and trivalent vanadium. In a positive electrolyte, the vanadium compound comprises one or both of quadrivalent and pentavalent vanadium. In an active material solution, the vanadium compound comprises one or both of trivalent and quadrivalent vanadium.

Abstract: Provided are a battery and a lead member, designed so that high strength of weld between them can be maintained with less variation despite the supply of lower welding current thereto when the lead member is welded to the outer surface of the battery by the parallel resistance welding method, and a battery pack using the same. A layer of an Ni-based alloy, e.g., an Ni—Fe alloy, is formed on a part or the whole of the outer surface of the battery. The lead member for battery connection is composed of a substrate and an Ni—Sn alloy layer formed on that surface of the substrate which is welded to the outer surface of the battery. The battery pack is composed of a battery group that is assembled by using the battery and/or the lead member and stored in a shell.

Abstract: Provided are a battery and a lead member, designed so that high strength of weld between them can be maintained with less variation despite the supply of lower welding current thereto when the lead member is welded to the outer surface of the battery by the parallel resistance welding method, and a battery pack using the same. A layer of an Ni-based alloy, e.g., an Ni—Fe alloy, is formed on a part or the whole of the outer surface of the battery. The lead member for battery connection is composed of a substrate and an Ni—Sn alloy layer formed on that surface of the substrate which is welded to the outer surface of the battery. The battery pack is composed of a battery group that is assembled by using the battery and/or the lead member and stored in a shell.