Ngk Insulators, Inc.

Hirohiko Iwasaka

Toshiyuki Mima

Michimasa Fujii

An excellent stable sodium-sulfur cell having a high mechanical strength and a very long life is provided. The cell eliminates formation of cracks in a joining portion of the solid electrolyte tube and the insulative ring of the cell with the aid of a solder glass filled in a gap between the solid electrolyte tube and the insulative ring, preferably with the aid of a tapered portion formed at at least one of the solid electrolyte tube and the insulative ring, thereby to completely obviate a direct reaction of active substances of the positive electrode and the negative electrode, overheating and destruction of the cell. The sodium-sulfur cell, includes a solid electrolyte tube, an insulative ring, a gap of 100-500 .mu.m formed between the solid electrolyte tube and the insulative ring, and a solder glass filled in the gap for joining the insulative ring to the solid electrolyte tube.

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Nagoya, Japan

Hirohiko Iwasaka