in a lithium secondary battery provided with a positive electrode capable of intercalating and eliminating lithium ions , a negative electrode capable of intercalating and eliminating lithium ions , and an electrolyte , at least one of an imide group lithium salt represented by lin and a methide group lithium salt represented by lic is contained as a chief component of a solute in the electrolyte , and one of or both of a fluoride and a phosphorus compound are added to the electrolyte .