RECTANGULAR LITHIUM SECONDARY BATTERY

• Main Authors: MARUYAMA AKIHIKO, ISHIZU TAKENORI, SOMA TAKAHIRO, KOSEKI MITSURU, YAGI YOSHIN
• Format: Patent
• Language: English; Japanese
• Published: 24.09.2015
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

PROBLEM TO BE SOLVED: To provide a rectangular lithium secondary battery in which exfoliation and cracking of a negative electrode active material on the innermost periphery of a wound electrode group are prevented without lowering the productivity.SOLUTION: A rectangular lithium secondary battery includes a flat wound electrode group formed by winding a sheet-like positive electrode and a sheet-like negative electrode while sandwiching a separator, and having corners at both ends, and a battery container for housing the wound electrode group. The negative electrode is arranged on the inner peripheral side of the positive electrode on the center side of the wound electrode group. A negative electrode active material mixture layer having a single side thickness of 50 μm or less is formed on both sides of the metal foil of the negative electrode. Adhesion strength of the negative electrode active material mixture layer and negative electrode metal foil is set to 0.05 N/mm or more, and the radius of curvature with reference to the inner surface of the metal foil of the negative electrode at the corner is set to 0.15 mm or more. 【課題】生産性を低下することなく、捲回電極群の最内周の負極活物質の脱落と割れを防止した角形リチウム二次電池を提供する。【解決手段】角形リチウム二次電池は、シート状の正極とシート状の負極とをセパレータを介して扁平形状に捲回し、両端にコーナー部を形成した扁平形状の捲回電極群と、捲回電極群を収納する電池容器とを備え、負極は、捲回電極群の中心側において正極よりも内周側に配置され、負極の金属箔の両面に片側厚み５０μｍ以下の負極活物質合剤層を形成し、負極活物質合剤層と負極金属箔との密着強度を０．０５Ｎ／ｍｍ以上とし、コーナー部における負極の金属箔の内側表面を基準とした曲率半径を０．１５ｍｍ以上とした。【選択図】図４