United Kingdom Atomic Energy Authority

Alan Hooper

John M North

Peter McGeehin

Esam Kronfli

Robin J Neat

Keith V Lovell

Keith T Harrison

A solid polymer electrolyte is in the form of a gel comprising a complex of a solid polymer (e.g. poly(ethene oxide) and an alkali metal salt (e.g. LiClO.sub.4), the polymer being cross-linked to inhibit its transformation from an amorphous form to a crystalline form thereby to improve the alkali metal ion conductivity of the electrolyte at lower temperatures. The electrolyte may be made by irradiating (e.g. by gamma radiation or an electron beam) a solution, preferably aqueous, of the complex to cause the polymer to cross-link and form a gel. The electrolyte may be used as a component in a solid state electrochemical cell (e.g. for a rechargeable lithium battery), where the gel form of the electrolyte assists fabrication.

Polymer electrolytes

A unitary polymer electrolyte/polymer-based cathode film component for use in a solid state electrochemical cell is manufactured by solution casting onto one of the electrolyte or cathode, a solution of the other of the electrolyte or cathode. The solution is prepared at elevated temperature (e.g. 40.degree.-50.degree. C.) and cooled to a lower temperature, e.g. ambient, before carrying out the casting. The solvent (e.g. methanol) is such that the polymer (e.g. poly (ethylene oxide)) is only sparingly soluble therein at the lower temperature and relatively readily soluble therein at the elevated temperature. Also, immediate precipitation of the polymer does not occur on cooling the solution from the elevated temperature to the lower temperature. In this way, dissolution of said one of the electrolyte or cathode is avoided.

Solid state cell manufacture

A solid state electrochemical cell comprises an anode having lithium as its active material, a polymeric electrolyte, and a cathode comprising a composite of an insertion electrode material or similarly active material and a polymeric material. One of the electrolyte and the cathode possesses an ionically conducting phase at ambient temperature and the other of the electrolyte and the cathode lacks such a phase. Ionic conductivity can be induced in said other of the electrolyte and cathode at elevated temperature thereby to render the cell operable and give rise to improvements in comparison with cells where such phases are present ab initio.

Electrochemical cell

The present invention relates to the preparation of materials and finds one application in the preparation of ion conductors and precursors therefor. There is disclosed a process for use in the preparation of a material of the general formula

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Faringdon, United Kingdom

Alan Hooper