NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Authors: YOGO JUNICHI, MURAOKA MASAFUMI, MINAMI YOSHIAKI
• Format: Patent
• Language: English; Japanese
• Published: 09.04.2020
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

To improve cycle characteristics in a non-aqueous electrolyte secondary battery including a flat wound electrode body having a flat portion and a curved portion.SOLUTION: In the non-aqueous electrolyte secondary battery, a negative electrode mixture layer includes a first region located in a flat part of an electrode body and a second region located in a pair of curved parts. A ratio (B/A) of packing density (B) of the second region to packing density (A) of the first region is 0.75 or more and 0.95 or less. Furthermore, in a cross section perpendicular to an axial direction passing through an axial center of the electrode body, a ratio (SB/SA) of an area (SB) of the pair of curved parts to an area (SA) of the flat part 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、負極合材層は、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領域の充填密度（Ａ）に対する第２領域の充填密度（Ｂ）の比率（Ｂ／Ａ）が、０．７５以上０．９５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