Abstract: The invention relates to novel cathodes for secondarylithium cells and to lithium cells which contain such cathodes. The secondary cells can be charged and discharged substantially more times than corresponding cells which contain conventional LiCoO.sub.2 type cathodes.The cathodes are based on crystalline compounds of the Li.sub.1 x M.sub.x/2 CoO.sub.2 type. One of the aspects of the invention is a process for the production of such crystalline cathodes, where M is selected from calcium, strontium, barium and magnesium and where the content of such bivalent cation M in the crystal is from about 0.1 weight-% to about 10 weight-%, preferably 0.2 to 5 weight-%. The novel crystalline cathode compound is synthesized by a solid/solid reaction at elevated temperature, generally in the 700.degree. C. to about 900.degree. C. range. The cathode may be prepared from small crystals of such a compound, in combination with a compatible binder or conductive material, such as graphite.

Abstract: There is provided an electrochemical charge with substantially increased safety. The cell contains a metal anode which can be alloyed by lithium, the preferred metals being selected from calcium, magnesium, and alloys of these, such cell comprising an electrolyte which is an aprotic solvent in which there is dissolved a suitable lithium salt, a cathode and a cathodic current collector. The anode can be initially charged with lithium. After a certain degree of discharge, certain embodiments of cells of the invention start forming a passivating layer on the anode preventing a runaway reaction.