NOVELTY - An electrolyte solution including additive is used for a lithium ion secondary battery using a positive electrode containing a positive electrode active material composed of lithium-manganese oxide including lithium and tetravalent manganese, and having a layered halite structure. The additive is chosen from open chain compound having sultone group, compound containing oxygen containing-heterocyclic ring, thiophene and/or thiophene derivative, tert-alkylbenzene and/or tert-alkylbenzene derivative, and N-alkyl pyrrole and/or N-alkyl pyrrole derivative.    USE - Electrolyte solution used for a lithium-ion secondary battery for vehicle (all claimed).    ADVANTAGE - The lithium-ion secondary battery using the electrolyte solution has improved storage and recovery capacity at high temperature.    DETAILED DESCRIPTION - An electrolyte solution including additive is used for a lithium ion secondary battery using a positive electrode containing a positive electrode active material composed of lithium-manganese oxide including lithium and tetravalent manganese and having a layered halite structure. The additive is chosen from open chain compound having sultone group, compound containing oxygen containing-heterocyclic ring, carbonyl group formed in one carbon atom adjacent to the oxygen atom of oxygen containing-heterocyclic ring and carboxyl group couple with the other carbon atom adjacent to the oxygen atom of oxygen containing-heterocyclic ring or alkyl group, thiophene and/or thiophene derivative, tert-alkylbenzene and/or tert-alkylbenzene derivative, N-alkyl pyrrole and/or N-alkyl pyrrole derivative, compound containing carbonyl group formed in the carbon atom adjacent to the oxygen atom which comprises an oxygen containing-heterocyclic ring and oxygen containing-heterocyclic ring, furan and/or furan derivative, polycyclic hydrocarbon compound of formula (I), and organosulfur compound and/or organosulfur derivative formed by coupling alkoxy group with at least one of carbon contained in the basic skeleton containing diphenyl disulfide. An INDEPENDENT CLAIM is included for lithium ion secondary battery, which has a positive electrode, a negative electrode and electrolyte solution.