US 9,812,708 B2
Cathode active material and lithium secondary battery comprising same
Chang-Wan Koo, Daejeon (KR); Moon Kyu Cho, Seoul (KR); Joon Sung Bae, Daejeon (KR); and Jae Bin Chung, Daejeon (KR)
Assigned to LG Chem, Ltd., (KR)
Appl. No. 14/353,173
Filed by LG Chem, Ltd., Seoul (KR)
PCT Filed Dec. 17, 2012, PCT No. PCT/KR2012/010977
§ 371(c)(1), (2) Date Apr. 21, 2014,
PCT Pub. No. WO2013/094942, PCT Pub. Date Jun. 27, 2013.
Claims priority of application No. 10-2011-0140175 (KR), filed on Dec. 22, 2011.
Prior Publication US 2015/0017529 A1, Jan. 15, 2015
Int. Cl. H01M 4/62 (2006.01); H01M 4/36 (2006.01); H01M 4/505 (2010.01); H01M 4/525 (2010.01); H01M 4/131 (2010.01); H01M 4/485 (2010.01); H01M 4/50 (2010.01); H01M 4/52 (2010.01); H01M 4/60 (2006.01); H01M 10/0525 (2010.01); H01M 10/052 (2010.01); H01M 4/02 (2006.01)
CPC H01M 4/366 (2013.01) [H01M 4/131 (2013.01); H01M 4/485 (2013.01); H01M 4/502 (2013.01); H01M 4/505 (2013.01); H01M 4/523 (2013.01); H01M 4/525 (2013.01); H01M 4/60 (2013.01); H01M 4/622 (2013.01); H01M 10/0525 (2013.01); H01M 10/052 (2013.01); H01M 2004/028 (2013.01)] 7 Claims
 
1. A cathode mixture for secondary batteries, comprising:
a cathode active material and a binder,
wherein the cathode active material, in which a carboxymethyl cellulose derivative is coated on surfaces of particles of a lithium transition metal oxide represented by Formula 1 below:
LixMyO2  <Formula 1>
wherein M is NiaMnbCoc where 0≤a≤0.9, 0≤b≤0.9, 0≤c≤0.5, and 0.85≤a+b+c≤1.05); and
x+y=2, wherein 0.95≤x≤1.15,
wherein the carboxymethyl cellulose derivative is a material represented by Formula 2 below:

OG Complex Work Unit Drawing
wherein at least one selected from the group consisting of R1, R2, and R3 is CH2CO2X and the remaining group is CH2CO2H or OH, wherein X is Na; and
n is an integer of 1 or more and is determined within a range within which the carboxymethyl cellulose derivative has a weight average molecular weight (Mw) of 1,700,000 to 2,300,000,
wherein a rate to which R1, R2, and R3 are CH2CO2X is 0.8 to 1.2,
wherein the binder is styrene-butadiene rubber,
wherein an amount of the binder is 1 wt % to 20 wt % based on a total weight of the cathode mixture, and
wherein a weight ratio of the carboxymethyl cellulose derivate:the styrene-butadiene rubber is 0.5:0.8 to 0.7:1.0.