US 12,463,211 B2
Positive electrode, nonaqueous electrolyte energy storage device, method of producing positive electrode, and method of producing nonaqueous electrolyte energy storage device
Shinya Uematsu, Kyoto (JP)
Assigned to GS Yuasa International Ltd., Kyoto (JP)
Appl. No. 16/761,375
Filed by GS Yuasa International Ltd., Kyoto (JP)
PCT Filed Nov. 6, 2018, PCT No. PCT/JP2018/041153
§ 371(c)(1), (2) Date May 4, 2020,
PCT Pub. No. WO2019/093313, PCT Pub. Date May 16, 2019.
Claims priority of application No. 2017-215569 (JP), filed on Nov. 8, 2017.
Prior Publication US 2020/0350577 A1, Nov. 5, 2020
Int. Cl. H01M 4/525 (2010.01); H01M 4/133 (2010.01); H01M 10/0525 (2010.01); H01M 4/02 (2006.01)
CPC H01M 4/525 (2013.01) [H01M 4/133 (2013.01); H01M 10/0525 (2013.01); H01M 2004/021 (2013.01); H01M 2004/028 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A positive electrode for a nonaqueous electrolyte energy storage device, comprising a positive composite having a density of 3.1 g/cm3 or more and 4 g/cm3 or less,
wherein the positive composite contains a positive active material containing nickel and citric acid,
the positive active material containing nickel includes at least one lithium transition metal composite oxide having a layered α-NaFeO2-type crystal structure, which is selected from a group consisting of Li[LixNi1-x]O2 (0≤x<0.5), Li[LixNiαCo(1-x-α)]O2 (0≤x<0.5, 0<α<1) and Li[LixNiαMnβCo(1-x-α-β]O2 (0≤x<0.5, 0<α, 0<β, 0.5<α+β<1),
a content of nickel in a transition metal in the positive active material is 33 mol % or more and 70 mol % or less,
a content of the citric acid is 0.01 parts by mass or more and 0.08 parts by mass or less based on 100 parts by mass of the positive active material,
a content of the positive active material in the positive composite is 70% by mass or more and 99% by mass or less, and
an increase in surface resistance of the positive electrode after being stored for two weeks in an environment at a temperature of 30° C. and a relative humidity of 55% is suppressed as compared to a comparative positive electrode comprising a positive composite having the density of 3.1 g/cm3 or more and 4 g/cm3 or less and containing the positive active material but not containing the citric acid, and/or an increase in surface resistance of the positive electrode after being stored for two weeks in an environment at a temperature of 50° C. and a relative humidity of 75% is suppressed as compared to the comparative positive electrode.