NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Authors: YOGO JUNICHI, MURAOKA MASAFUMI, MINAMI YOSHIAKI
• Format: Patent
• Language: English; Japanese
• Published: 02.04.2020
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

To improve the cycle characteristics in a nonaqueous electrolyte secondary battery having a flat wound electrode body having a flat portion and a curved portion.SOLUTION: In a nonaqueous electrolyte secondary battery according to an embodiment, a separator includes a first region located on the flat portion of an electrode body and a second region located on a pair of curved portions, and the ratio (B/A) of the air permeability of the second region with respect to the air permeability of the first region (A) is 0.5 or more and 0.9 or less. Further, in a cross section perpendicular to the axial direction passing through the axial center of the electrode body, the ratio (SB/SA) of the cross-sectional area (SB) of the pair of curved portions to the cross-sectional area (SA) of the flat portion is 0.28 or more and 0.32 or less.SELECTED DRAWING: Figure 3 【課題】平坦部及び湾曲部を有する扁平状の巻回型電極体を備えた非水電解質二次電池において、サイクル特性を向上させる。【解決手段】実施形態の一例である非水電解質二次電池において、セパレータは、電極体の平坦部に位置する第１領域と、一対の湾曲部に位置する第２領域とを含み、第１領域の透気度（Ａ）に対する前記第２領域の透気度（Ｂ）の比率（Ｂ／Ａ）が、０．５以上０．９以下である。さらに、電極体の軸方向中央を通る当該軸方向に垂直な断面において、平坦部の断面積（ＳＡ）に対する一対の湾曲部の断面積（ＳＢ）の比率（ＳＢ／ＳＡ）が、０．２８以上０．３２以下である。【選択図】図３