Abstract: Electrochemical insertion of lithium into titanium dioxide initially in its rutile form, the insertion being performed at an elevated temperature (for example 120.degree. C.), produces a material Li.sub.x TiO.sub.2 with x between 0.5 and 1.0. This material is suitable as an active cathode material in a secondary cell as it can be repeatedly recycled. The material has a crystal struture, different from that of the initial rutile titania, which is believed to be hexagonal.

Abstract: A battery having at least one electrochemical cell, comprises a negative electrode, a positive electrode, and a solid electrolyte between and in contact with the electrodes. There is dispersed in the solid electrolyte (6) a material that is reactive with one of the electrodes. But the electrolyte in contact with that one electrode is free from this material.

Abstract: A secondary electrochemical cell is made by(i) assembling a solid state electrochemical cell having an anode containing an alkali metal such as lithium as active anode material; a solid alkali metal ion conducting electrolyte, for example a polymer electrolyte comprising a complex of a solid polymer (e.g. poly(ethylene oxide)) and an alkali metal salt (e.g. LiClO.sub.4), which polymer is capable of forming donor-acceptor type bonds with alkali metal ions; and a cathode containing manganese (IV) oxide as active cathode material; and(ii) discharging the cell under conditions, e.g. of elevated temperature, such that the cathode material is transformed in situ into a rechargeable cathode material which may, for example be LiMn.sub.2 O.sub.4.

Abstract: 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.

Abstract: A material which is particularly suitable for use in a composite cathode and which includes a complex of a salt formed between a metal ion capable of existing in at least two stable valency states or an aluminium ion together with a suitable anion and a solid plastics polymeric composition capable of forming a donor acceptor type bond with the metal or aluminium ion, wherein the material exhibits both ionic and electronic conductivities to a substantial degree.