Abstract: The invention relates to high energy density electrochemical generators of the alkaline, more particularly lithium, negative electrode type. An electrolyte whose solvent contains 1-3 dioxane, dioxolane or propylene oxide, preferably mixed with propylene carbonate or ethylene carbonate is utilized.This electrolyte has excellent conductivity, even at a relatively slight concentration of the solute. Lithium perchlorate is preferred as the solute and copper oxide, monovalent silver chromate, lead chromate, fluorinated carbons, polymerized fluorinated carbons or mixtures of these latter with metal compounds are preferred as active positive material.