リチウムイオン二次電池

Japanese Patent JP7069668

B2

To provide a lithium ion secondary battery by which the Li salt concentration in an electrolyte solution in high-rate charge/discharge can be suppressed from being biased.SOLUTION: A lithium ion secondary battery comprises a positive electrode 100, a negative electrode and an electrolyte solution. The positive electrode includes a current collector 1, and a positive electrode mixture material layer 2 provided on a surface of the current collector. The positive electrode mixture material layer includes Li-containing active material particles and a binder. The active material particles include primary particles 201, and small particles 202 smaller, in particle diameter, than the primary particles. The volume density of the positive electrode mixture material layer is 3.0-4.0 g/cm. When in a section of the positive electrode mixture material layer in a thickness direction thereof, the ratio of a total area of gaps in a circumscribed circle 202a of a particle group into which three or more small particles 1 μm or more in particle diameter are gathered with an inter-particle distance of 20-4 μm to a total area of gaps in the mixture material layer is denoted by η, and the section is equally divided in five in the thickness direction, η(η) in one region of the resultant five regions, which is closest to the current collector is equal to or larger than 1.019 times of η(η) in one region of the five regions, which is farthest from the current collector.SELECTED DRAWING: Figure 1

Shingo Komura

JP2017231633A

May 18, 2022

December 01, 2017

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TOYOTA JIDOSHA KABUSHIKI KAISHA

H01M4/13; H01M4/36; H01M4/62; H01M10/052; H01M10/0566

JP2014099368A
JP2002151055A
JP2006228733A
JP2013012391A
JP2006278265A

WO2015198521A1
US20120064410
KR1020140098347A

Fukami patent office

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