NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Authors: TSUJIKO AKIRA, SUZUKI SHINYA
• Format: Patent
• Language: English; Japanese
• Published: 24.11.2023
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

To provide a nonaqueous electrolyte secondary battery which exhibits high energy density and which is operable to suppress gas generation under a high-voltage condition.SOLUTION: A nonaqueous electrolyte secondary battery herein disclosed comprises a positive electrode 50. The positive electrode includes a positive electrode active material layer 54 of a multilayer structure having a positive electrode lower layer 54A located near a positive electrode collector 52, and a positive electrode upper layer 54B farther from the positive electrode collector 52. The positive electrode lower layer 54A contains a first positive electrode active material including a first Ni-containing lithium composite oxide of under 2% in porosity. The positive electrode upper layer 54B contains a second positive electrode active material including a second Ni-containing lithium composite oxide configured of secondary particles resulting from agglomeration of primary particles and having porosity of 2-20%, provided that the secondary particles have therein no pore or cavity larger than an average cross section of the primary particles, and a coating element. Supposing that metal elements of the second Ni-containing lithium composite oxide are 100 mol% in total, a proportion of the coating element is 0.5-3 mol%.SELECTED DRAWING: Figure 2 【課題】高エネルギー密度でかつ高電圧下におけるガスの発生が抑制された非水電解質二次電池を提供する。【解決手段】ここに開示される非水電解質二次電池の正極５０は、正極集電体５２に近い正極下層５４Ａと、正極集電体５２から離れた正極上層５４Ｂと、を備える複層構造の正極活物質層５４を備える。正極下層５４Ａは、空隙率が２％未満の第１のＮｉ含有リチウム複合酸化物を含む第１正極活物質を備える。正極上層５４Ｂは、次粒子が凝集してなる二次粒子状で、空隙率が２～２０％で、上記二次粒子の内部には上記一次粒子の平均断面積よりも大きい空隙が存在しない第２のＮｉ含有リチウム複合酸化物と、被覆元素と、を含む第２正極活物質を備える。上記被覆元素の割合は、上記第２のＮｉ含有リチウム複合酸化物の金属元素の合計を１００モル％としたときに０．５～３モル％である。【選択図】図２