US 12,315,916 B2
Positive electrode active material for lithium ion secondary battery and lithium ion secondary battery
Tetsutaro Hayashi, Niihama (JP); Willy Shun Kai Bong, Niihama (JP); Shinsuke Suganuma, Niihama (JP); and Toshihiro Kato, Tokyo (JP)
Assigned to SUMITOMO METAL MINING CO., LTD., Tokyo (JP)
Appl. No. 17/761,852
Filed by SUMITOMO METAL MINING CO., LTD., Tokyo (JP)
PCT Filed Sep. 18, 2020, PCT No. PCT/JP2020/035590
§ 371(c)(1), (2) Date Mar. 18, 2022,
PCT Pub. No. WO2021/054468, PCT Pub. Date Mar. 25, 2021.
Claims priority of application No. 2019-170440 (JP), filed on Sep. 19, 2019.
Prior Publication US 2022/0367859 A1, Nov. 17, 2022
Int. Cl. H01M 4/525 (2010.01); H01M 4/36 (2006.01); H01M 4/505 (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 2004/021 (2013.01); H01M 2004/028 (2013.01)] 10 Claims
 
1. A positive electrode active material for a lithium ion secondary battery, the positive electrode active material comprising:
lithium transition metal-containing composite oxide particles having a composition represented by general formula (A): Li1+uNixMnyCozM1tO2, where −0.05≤u≤0.50, x+y+z+t=1, 0.3≤x≤0.9, 0≤y≤0.5, 0≤z≤0.5, 0≤t≤0.05, and M1 is one or more additive elements selected from Mg, Al, Si, Ca, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, and a layered rock salt type crystal structure; and
a coating layer present on at least a part of a surface of the lithium transition metal-containing composite oxide particles and formed of fine particles and/or a coating film of a metal composite oxide of Li and a metal element M2, where M2 represents one or more metal elements selected from Al, Ti, Zr, Nb, Mo, and W,
the lithium transition metal-containing composite oxide particles formed of secondary particles, the secondary particles each formed of an aggregation of primary particles,
the lithium transition metal-containing composite oxide particles including the coating layer having a 50% cumulative diameter d50 of 3.0 μm or more and 7.0 μm or less, the 50% cumulative diameter d50 being determined from a particle size distribution measured value, a BET specific surface area of 2.0 m2/g or more and 5.0 m2/g or less, a tap density of 1.0 g/cm3 or more and 2.0 g/cm3 or less, and an oil absorption amount determined by operation according to a procedure described in JIS K 6217-4:2008 of 30 ml/100 g or more and 60 ml/100 g or less,
for each of a plurality of primary particles having a primary particle size within a range of 0.1 μm or more and 1.0 μm or less among the primary particles, when a concentration of the additive element M1 is measured at a plurality of locations by cross-sectional STEM or TEM-EDX analysis, and a coefficient of variation, which is a value obtained by dividing a standard deviation of a concentration of the concentration of the additive element M1 by an average concentration of the additive element M1, is calculated, the coefficient of variation being 1.5 or less, and
the amount of M2 contained in the coating layer being 0.1 atom % or more and 1.5 atom % or less with respect to the total number of atoms of Ni, Mn, and Co contained in the lithium transition metal-containing composite oxide particles.