US 12,334,552 B2
Positive active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same
Jeom-Soo Kim, Hwaseong-si (KR); and Byeong Cheol Min, Busan (KR)
Assigned to DONG-A UNIVERSITY RESEARCH FOUNDATION FOR INDUSTRY-ACADEMY COOPERATION, Busan (KR)
Filed by Dong-A University Research Foundation For Industry-Academy Cooperation, Busan (KR)
Filed on May 4, 2020, as Appl. No. 16/865,589.
Claims priority of application No. 10-2019-0051867 (KR), filed on May 2, 2019.
Prior Publication US 2020/0350581 A1, Nov. 5, 2020
Int. Cl. H01M 4/525 (2010.01); C01G 53/50 (2025.01); H01M 4/04 (2006.01); H01M 4/131 (2010.01); H01M 4/1391 (2010.01); H01M 4/36 (2006.01); H01M 10/0525 (2010.01); H01M 4/02 (2006.01)
CPC H01M 4/525 (2013.01) [C01G 53/50 (2013.01); H01M 4/0471 (2013.01); H01M 4/131 (2013.01); H01M 4/1391 (2013.01); H01M 4/366 (2013.01); H01M 10/0525 (2013.01); C01P 2002/85 (2013.01); C01P 2004/03 (2013.01); H01M 2004/021 (2013.01); H01M 2004/028 (2013.01); Y02E 60/10 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A positive active material for a rechargeable lithium battery, comprising
secondary particles of a nickel-based transition metal oxide composed of an inner portion and an outer portion,
wherein the inner portion has a dense structure having a higher density than the outer portion,
the secondary particles of the nickel-based transition metal oxide have a plurality of protruding portions on the surface thereof, and
the positive active material has an area ratio of 25% to 30% occupied by protrusions calculated by Equation 1 based on a cross-section of the secondary particles of the nickel-based transition metal oxide:
[At−Ai]/At  [Equation 1]
wherein, in Equation 1,
At is a total area of the secondary particle of the nickel-based transition metal oxide, and
Ai is an area of an inner circle with a radius from the inner end of a vertically oriented primary particle constituting each of the protruding portions to the center of the secondary particle of the nickel-based transition metal oxide,
wherein the primary particle constituting each of the protruding portions have a concentration gradient in which a fraction of cobalt (Co) decreases from an outer end portion to an inner end portion of each of the protruding portions,
wherein when a length of a narrowest portion of each of the protruding portions is a width (W) and a length from an outer end portion of each of the protruding portions to the inner circle is a height (H),
the width (W) is 0.25 μm to 0.60 μm, and
the height (H) is 0.65 μm to 1.00 μm.