US 12,255,319 B2
Positive electrode for lithium ion secondary batteries, and lithium ion secondary battery
Takeshi Miki, Ibaraki (JP); Yuki Takei, Ibaraki (JP); Yusuke Tachikawa, Ibaraki (JP); and Shuichi Suzuki, Ibaraki (JP)
Assigned to VEHICLE ENERGY JAPAN INC., Hitachinaka (JP)
Appl. No. 17/760,913
Filed by Vehicle Energy Japan Inc., Hitachinaka (JP)
PCT Filed Nov. 12, 2020, PCT No. PCT/JP2020/042320
§ 371(c)(1), (2) Date Mar. 16, 2022,
PCT Pub. No. WO2021/095818, PCT Pub. Date May 20, 2021.
Claims priority of application No. 2019-207241 (JP), filed on Nov. 15, 2019.
Prior Publication US 2022/0352505 A1, Nov. 3, 2022
Int. Cl. H01M 4/36 (2006.01); H01M 4/505 (2010.01); H01M 4/525 (2010.01); H01M 10/0525 (2010.01); H01M 4/02 (2006.01)
CPC H01M 4/366 (2013.01) [H01M 4/505 (2013.01); H01M 4/525 (2013.01); H01M 10/0525 (2013.01); H01M 2004/028 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A positive electrode for a lithium ion secondary battery, comprising:
a positive-electrode current collector; and
a layered structure provided on the positive-electrode current collector,
wherein:
the layered structure includes an outermost layer most distant from the positive-electrode current collector, and an innermost layer closest to the positive-electrode current collector,
the outermost layer contains a first positive-electrode active material represented by the following Formula (1):
Li1+XMAO2  (1)
wherein X satisfies −0.15≤X≤0.15,
MA represents an element group including Ni, Co, and Mn, and
provided that proportions of Ni, Co, and Mn in all elements of MA are respectively represented by a (mol %), b (mol %), and c (mol %), a, b, and c satisfy 0<a/(b+c)≤0.67 and 1.4≤b/c≤2, and
the innermost layer contains a second positive-electrode active material represented by the following Formula (2):
Li1+YMBO2  (2)
wherein Y satisfies −0.15≤Y≤0.15,
MB represents an element group including Ni, Co, and at least one of Mn or Al, and
provided that proportions of Ni, Co, Mn, and Al in all elements of MB are respectively represented by d (mol %), e (mol %), f (mol %), and g (mol %), d, e, f, and g satisfy 1≤d/(e+f+g)≤4.