Secondary battery

A secondary battery, comprising:

• a laminated electrode body having a structure in which a positive electrode having a rectangular sheet-shaped positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and a negative electrode having a rectangular sheet-shaped negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector are alternately laminated, with a rectangular sheet-shaped separator interposed between the electrodes;
• an electrolyte;
• and
• a square case, wherein
• a positive electrode current-collecting portion and a negative electrode current-collecting portion electrically connected to external connection terminals are respectively provided inside the case,
• a positive electrode current collector-exposed portion and a negative electrode current collector-exposed portion which do not include the active material layers are respectively formed along a short-side direction at respective first ends in a long-side direction of the positive electrode and the negative electrode,
• the laminated electrode body is structured in a state where the positive electrode current collector-exposed portion is laminated at a first end in the long-side direction and the negative electrode current collector-exposed portion is laminated at a second end in the long-side direction,
• the laminated positive electrode current collector-exposed portion and the laminated negative electrode current collector-exposed portion respectively constitute a plurality of current collector bundles which are bundled while being divided into two or more in a direction of lamination thereof, and each of the plurality of current collector bundles is individually and separately joined to the current collector portion on the same electrode side, and
• any of separators existing between any of the positive and negative electrodes located at a first end in the direction of lamination and any of the positive and negative electrodes located at a second end in the direction of lamination among the positive electrode and the negative electrode included in the laminated electrode body is enveloped in any of the plurality of current collector bundles on a side of the positive electrode current collector-exposed portion and/or any of the plurality of current collector bundles on a side of the negative electrode current collector-exposed portion.