Hitachi, Ltd.

The Tokyo Electric Power Company, Incorporated

Hiroyuki Kawamoto

Toshihiro Yamada

Akiomi Kohno

Kazuaki Yokoi

Eiji Takahashi

Akihiko Yamamoto

Sadao Mori

Hideo Nakae

Yoshiteru Miyatake

Motohiro Satou

Mitsuo Kawakami

Yasumasa Ishida

Motoi Wada

Hisamitu Hatoh

Disclosed is a method and apparatus which can detect progress of degradation of a sodium-sulfur cell and predict possibility of final breakdown of the cell in a very near future before such a final breakdown of the cell actually occurs. The method and apparatus for diagnosing the presence or absence of an abnormal state in the sodium-sulfur cell, containing a porous electrical conductive material impregnated with molten sulfur or sodium polysulfide as its positive electrode reactant and containing sodium as its negative electrode reactant, comprises observing the operating voltage of the cell during charging and discharging so as to detect occurrence of a minute ripple in the operating voltage, and, when the amplitude of the ripple and the frequency of occurrence of the ripple increases as a result of repeated cycles of charging and discharging, deciding that degradation of the cell has progressed to an extent that final breakdown of the cell will occur in a very near future.

Method and apparatus for diagnosing abnormal state of sodium

The present invention relates to a sodium-sulfur electric cell structure having a specific joint between a cathode tube and an anode tube. The cathode and anode tubes are each made of an iron-nickel base alloy and are joined to each other through the medium of a ceramic ring and an aluminum alloy insert provided on both sides of the ceramic ring. A chromium or chromium-rich layer is formed at the joint boundary between the insert and each tube. The sodium-sulfur electric cell having such a structure eliminates a problem of the occurrence of cracking, improves the airtightness and enables the production of large-sized electric cells.

Sodium-sulfur electric cell and process for manufacturing the same

When a ceramic is bonded to a metal having a low thermal expansion, if a Cr layer of a Cr diffusion layer is formed on the surface of the metal and the ceramic is bonded to the metal through this Cr layer or Cr diffusion layer by an Al insert, a bonded structure having a good air-tightness and a high strength is obtained.

Method for bonding ceramic to metal

A method of bonding alumina to a metal characterized in that an aluminum or aluminum-base alloy sheet is inserted between the alumina and the metal when they are bonded together by being heated and pressed, thereby obtaining a product which has a high reliability in strength at the joint and a high dimensional accuracy.

Method of bonding alumina to metal

A sodium-sulfur cell block having a plurality of sodium-sulfur cells is attached to, and held by, common terminals at both ends of the cells and in the long axes directions of the cells. In order to absorb thermal stress generated between the cells and the common terminals, at least one end is cantilevered at said common terminal.

Sodium-sulfur cell block

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Hitachi, Japan

Hiroyuki Kawamoto