| 摘要 |
PROBLEM TO BE SOLVED: To improve corrosion resistance to sulfur vapor of the weld part of a positive electrode lid to a battery jar and minimize the thermal stresses applied to the connection part by using a ferrite-based stainless, having a chromium content of a specified wt.% in at least one of the positive electrode lid and the battery jar. SOLUTION: A ferrite-based stainless having a chromium content of 10-35 wt.% is used. This ferrite-based stainless preferably has a chromium-iron alloy later formed by chromizing on the surface. Accordingly, the vicinity of the welded part of a positive electrode lid to a battery jar can be prevented from being corroded by an evaporated positive electrode active material. Furthermore, since the difference in thermal expansion coefficients between the ferrite-based stainless andα-alumina is smaller than that between iron andα-alumina, the thermal stress due to heat cycle can be also small.
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