	US 12,142,759 B2
	Positive electrode active material and secondary battery
Mayumi Mikami, Kanagawa (JP); Yohei Momma, Kanagawa (JP); and Teruaki Ochiai, Kanagawa (JP)
Assigned to Semiconductor Energy Laboratory Co., Ltd., Atsugi (JP)
Appl. No. 17/291,463
Filed by SEMICONDUCTOR ENERGY LABORATORY CO., LTD., Atsugi (JP)
PCT Filed Nov. 7, 2019, PCT No. PCT/IB2019/059561 § 371(c)(1), (2) Date May 5, 2021, PCT Pub. No. WO2020/104881, PCT Pub. Date May 28, 2020.
Claims priority of application No. 2018-218362 (JP), filed on Nov. 21, 2018.
Prior Publication US 2022/0006082 A1, Jan. 6, 2022
Int. Cl. H01M 4/525 (2010.01); H01M 4/02 (2006.01); H01M 4/505 (2010.01); H01M 10/0525 (2010.01)

CPC H01M 4/525 (2013.01) [H01M 4/505 (2013.01); H01M 10/0525 (2013.01); H01M 2004/028 (2013.01)]

8 Claims

6. A positive electrode active material comprising:

lithium, cobalt, magnesium, and oxygen,

wherein a first spin density attributed to one or both of a bivalent cobalt ion and a tetravalent cobalt ion is greater than or equal to 2.0×10¹⁷spins/g and less than or equal to 1.0×10¹⁸spins/g,

wherein the first spin density is measured at a temperature set to 300 K,

wherein a second spin density attributed to one or both of a bivalent cobalt ion and a tetravalent cobalt ion is greater than or equal to 2.0×10¹⁷spins/g and less than or equal to 1.0×10¹⁸spins/g,

wherein the second spin density is measured at a temperature set to 200 K,

wherein a third spin density attributed to one or both of a bivalent cobalt ion and a tetravalent cobalt ion is greater than or equal to 2.0×10¹⁷spins/g and less than or equal to 1.0×10¹⁸spins/g,

wherein the third spin density is measured at a temperature set to 113 K,

wherein the third spin density is larger than the second spin density, and

wherein the second spin density is larger than the first spin density.