NONAQUEOUS-ELECTROLYTE SECONDARY BATTERY

[Object] Provided is a means capable of reducing an error in displaying a remaining capacity of a non-aqueous electrolyte secondary battery that uses a spinel type lithium manganese composite oxide as a positive electrode active substance and in particular is expected to be used under high output conditions (has a low internal resistance of 10 mΩ/Ah or less (SOC of 50%)), even if there is a temporary drop in cell voltage due to high output load or the like during use of a battery. [0002] [Solving Means] Disclosed is a non-aqueous electrolyte secondary battery which has the internal resistance of 10 mΩ/Ah or less (SOC of 50%) and has a power generating element containing the following: a positive electrode obtained by forming, on the surface of a positive electrode current collector, a positive electrode active substance layer containing a positive electrode active substance; a negative electrode obtained by forming, on the surface of a negative electrode current collector, a negative electrode active substance layer containing a negative electrode active substance; and a separator. The positive electrode active substance is made to contain a spinel type lithium manganese composite oxide and a lithium nickel-based composite oxide, and the mixing ratio of the lithium nickel-based composite oxide is 50 to 70% by weight relative to the total 100% by weight of the spinel type manganese positive electrode active substance and the lithium nickel-based composite oxide.