LITHIUM ION SECONDARY BATTERY

• Main Authors: SEKI HIDEAKI, KIDO RYOSUKE
• Format: Patent
• Language: English; Japanese
• Published: 10.10.2019
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

To provide a lithium ion secondary battery having high rate characteristics.SOLUTION: In a lithium ion secondary battery including a positive electrode, a negative electrode and electrolyte, the positive electrode contains positive electrode active material particles containing one or more kinds of compounds containing Li and a transition metal, the positive electrode active material particle has a coating layer on at least a part of the surface, the coating layer contains at least one kind of carbon material, and the thickness of the coating layer satisfies following mathematical formula (1). Mathematical formula (1): 0.07≤T/T≤0.45 ... (1). (In the mathematical formula (1), Trepresents the maximum thickness of the coating layer, and Trepresents the minimum thickness of the coating layer).SELECTED DRAWING: Figure 1 【課題】高いレート特性を有するリチウムイオン二次電池を提供すること。【解決手段】正極と、負極と、電解質とを含むリチウムイオン二次電池であって、前記正極は、Ｌｉ及び遷移金属を含む化合物を一種以上含む正極活物質粒子を含み、前記正極活物質粒子は表面の少なくとも一部に被覆層を有し、前記被覆層は炭素材料を少なくとも一種を含み、前記被覆層の厚みが下記数式（１）を満たすことを特徴とするリチウムイオン二次電池。数式（１）：０．０７≦Ｔｍｉｎ／Ｔｍａｘ≦０．４５ ・・・（１）（上記数式１においてＴｍａｘは上記被覆層の最大厚みを表し、Ｔｍｉｎは上記被覆層の最小厚みを表す。）【選択図】図１