Solid electrolyte material incorporating beta-alumina ceramic, its manufacture and sodium-sulphur cells and other energy conversion devices utilising such material

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Listed from its EPO record in Patent Yard's archive of European patents past their term. Its claims, description and drawings are in the EPO PDF and on Google Patents, and the Claude kit works from them.

Why it's free to use

• Filed August 7, 1981 and granted May 9, 1984. A European patent lasts at most 20 years from filing, so its term ended August 7, 2001.
• A supplementary protection certificate, which can extend a medicine or crop-protection patent, adds at most five and a half years, so even that would have ended by February 7, 2007.
• We check European rights only. A US or other national patent in its family could still be in force: check its family on Espacenet or Google Patents.