US 12,406,983 B2
Lithium ion secondary battery and method for manufacturing same
Hiroyuki Toshiro, Hitachinaka (JP); and Yasuo Arishima, Hitachinaka (JP)
Assigned to VEHICLE ENERGY JAPAN INC., Ibaraki (JP)
Filed by Vehicle Energy Japan Inc., Hitachinaka (JP)
Filed on Jun. 3, 2024, as Appl. No. 18/732,136.
Application 18/732,136 is a continuation of application No. 17/292,293, granted, now 12,034,150, previously published as PCT/JP2019/042865, filed on Oct. 31, 2019.
Claims priority of application No. 2018-212635 (JP), filed on Nov. 13, 2018.
Prior Publication US 2024/0322125 A1, Sep. 26, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H01M 4/36 (2006.01); H01M 4/131 (2010.01); H01M 4/139 (2010.01); H01M 4/505 (2010.01); H01M 4/525 (2010.01); H01M 10/0525 (2010.01); H01M 10/0587 (2010.01); H01M 4/02 (2006.01)
CPC H01M 4/364 (2013.01) [H01M 4/131 (2013.01); H01M 4/139 (2013.01); H01M 4/366 (2013.01); H01M 4/505 (2013.01); H01M 4/525 (2013.01); H01M 10/0525 (2013.01); H01M 10/0587 (2013.01); H01M 2004/021 (2013.01); H01M 2004/028 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A lithium ion secondary battery comprising:
a positive electrode;
a negative electrode; and
a separator,
wherein the positive electrode includes a positive electrode current collector foil and a positive electrode mixture layer disposed on a surface of the positive electrode current collector foil,
wherein the positive electrode mixture layer includes a superficial layer portion and a deep layer portion, the superficial layer portion opposes the negative electrode via the separator, and the deep layer portion is disposed between the superficial layer portion and the positive electrode current collector foil,
wherein the superficial layer portion contains positive electrode active material particles having an average particle diameter larger than an average particle diameter of positive electrode active material particles contained in the deep layer portion,
wherein a space ratio between the positive electrode active material particles in the superficial layer portion is lower than a space ratio between the positive electrode active material particles in the deep layer portion;
wherein a cobalt content of the positive electrode active material particles contained in the superficial layer portion is higher than a cobalt content of the positive electrode active material particles contained in the deep layer portion;
wherein the positive electrode active material particles contained in at least one of the superficial layer portion and the deep layer portion are composed of a nickel cobalt lithium manganate and
wherein a ratio of cobalt metal elements constituting anions of the positive electrode active material particles composed of the nickel cobalt lithium manganate is more than 18% and less than 40% in terms of molar percentage with respect to all metals constituting anions.