NOVELTY - A lithium ion secondary battery (10) comprises positive electrode having positive electrode active material layer (15) which contains positive electrode active material formed on surface of electrical power collector (14), electrolyte layer (13) containing electrolyte solution, negative electrode having negative electrode active material layer (12) which contains negative electrode active material formed on surface of electrical power collector (11), and electric power generation element containing greater than or equal to 1 cell layers (16) which are sequentially laminated.    USE - A lithium ion secondary battery for motor drive, such as electric vehicle (EV), hybrid electric vehicle (HEV), and fuel cell electric vehicle (FCV).    ADVANTAGE - The lithium ion secondary battery has high safety in which temperature increase of battery is suppressed by adding 3-14 mass% lithium hydrogen carbonate with respect to total mass of electrolyte solution.    DETAILED DESCRIPTION - A lithium ion secondary battery comprises positive electrode having positive electrode active material layer which contains positive electrode active material formed on surface of electrical power collector, electrolyte layer containing electrolyte solution, negative electrode having negative electrode active material layer which contains negative electrode active material formed on surface of electrical power collector, and electric power generation element containing greater than or equal to 1 cell layers which are sequentially laminated. Positive electrode active material layer, negative electrode active material layer, or electrolyte layer contains lithium hydrogen carbonate in an amount of 3-14 mass% with respect to total mass of electrolyte solution.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional diagram of the lithium ion secondary battery structure which is not flat-type dipolar-type.    Lithium ion secondary battery (10)    Negative electrode electrical power collector (11)    Negative electrode active material layer (12)    Electrolyte layer (13)    Positive electrode electrical power collector (14)    Positive electrode active material layer (15)    Cell layer (16)