CPC H01M 4/622 (2013.01) [C01G 53/50 (2013.01); H01M 4/0404 (2013.01); H01M 4/505 (2013.01); H01M 4/525 (2013.01); H01M 2004/028 (2013.01)] | 6 Claims |
1. A method of producing a slurry composition for a secondary battery positive electrode containing an organic solvent, a positive electrode active material, and a polymer including a nitrile group-containing monomer unit and a linear alkylene structural unit having a carbon number of 4 or more, the method comprising
preparing the polymer by polymerizing a monomer composition containing at least a nitrile group-containing monomer and at least one of a conjugated diene monomer or a 1-olefin monomer, having a carbon number of 4 or more, in a solvent including deionized water to produce a polymer solution,
adding at least one of a pH modifier or a buffer solution into the polymer solution, followed by exchanging the solvent including the deionized water with the organic solvent, and
mixing the polymer accompanying the organic solvent with the positive electrode active material, wherein
the polymer satisfies a certain attribute of an extract obtained according to a method including:
preparing an 8 mass % N-methyl-2-pyrrolidone solution of the polymer;
diluting the 8 mass % N-methyl-2-pyrrolidone solution of the polymer by a factor of 10 with diluent of deionized water; and
stirring and pressing the polymer to extract liquid encapsulated in the polymer into the diluent so as to obtain an extract,
the certain attribute of the extract is a pH of not lower than 3.5 and lower than 6.0, and
the positive electrode active material has a chemical composition represented by formula (I), shown below,
LiαNiaCobMncMdO2-(β/2)Xβ (1)
where, in formula (I):
M is an element selected from the group consisting of Mg, Al, Cr, V, Ti, Cr, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, and combinations thereof;
X is a halogen element; and
α, β, a, b, c, and d satisfy conditions (1) to (8), shown below:
0.90≤α≤1.5 (1)
0≤β≤0.1 (2)
0.55≤a≤0.9 (3)
0≤b≤0.45 (4)
0≤c≤0.45 (5)
0≤d≤0.1 (6)
0.1≤b+c+d≤0.45 (7)
a+b+c+d=1 (8).
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