Positive active material for a nickel electrode
A nickel hydroxide material for use as an active material in positive electrodes for electrochemical cells. The nickel hydroxide material includes one or more modifiers which provide for a small crystallite size and high capacity without adversely affecting performance of the nickel hydroxide material.
1 . A positive electrode active material having the formula (Ni a Co b Zn c Cu d Mg e )(OH) 2 , wherein 0.890≦a; 0.000<b≦0.050; 0.000<c≦0.055; 0.005<d≦0.050; 0.000<e≦0.050; and a+b+c+d+e=1.000.
2 . The nickel hydroxide active material according to claim 1 , wherein 0.005<d≦0.035.
3 . The nickel hydroxide active material according to claim 1 , wherein 0.025<d<0.035.
4 . The nickel hydroxide active material according to claim 1 , wherein 0.890≦a≦0.950.
5 . The nickel hydroxide active material according to claim 4 , wherein 0.920≦a≦0.950.
6 . The nickel hydroxide active material according to claim 1 , wherein 0.020<b≦0.040.
7 . The nickel hydroxide active material according to claim 1 , wherein 0.005<c<0.025.
8 . The nickel hydroxide active material according to claim 1 , wherein 0.0<e≦0.015.
9 . A positive electrode active material comprising:
a nickel hydroxide material having a crystallite size of less than 100 angstroms, said nickel hydroxide material including up to 5 atomic percent copper.
10 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide further comprises 2.0 to 4.0 atomic percent cobalt.
11 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide further comprises 0.5 to 5.5 atomic percent zinc.
12 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide further comprises up to 1.5 atomic percent magnesium.
13 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide material has a tap density of 2.00 to 2.35 g/cc.
14 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide material has a tap density of 2.20 to 2.35 g/cc.
15 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide material has an average particle size based on volume of 5 to 25 μm.
16 . The positive electrode active material according to claim 9 , wherein said nickel hydroxide material has a BET surface area of 5-30 m 2 /g.
17 . A positive electrode active material comprising:
a nickel hydroxide material including one or more modifier elements, said modifier elements providing said nickel hydroxide material with a crystallite size of less than 100 angstroms while maintaining a tap density in the range of 2.00 to 2.35 and an average particle size based on volume of 5 to 25 μm.
18 . The positive electrode active material according to claim 17 , wherein said one or more modifier elements are selected from copper, zinc, cobalt, and magnesium.