LITHIUM ION SECONDARY BATTERY

In order to provide a lithium ion secondary battery having both high energy density and an excellent charge-rate characteristic, there is provided a lithium ion secondary battery including a positive electrode containing a positive electrode active material made of a lithium composite oxide, and nano-carbon having a Li ion diffusion path as an additive, and an electrolyte solution containing 0.5 mol/l or more of Li[(FSO)N] as an electrolyte, LiPOFas an additive, and a ternary-system of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), as solvents.