Cathode, membrane electrode assembly, and battery
A cathode, a membrane electrode assembly, and a battery, each has excellent durability. The cathode is a cathode of a battery including an electrolyte membrane, the cathode including: a first layer which contains 0.3 mg/cm 2 or more and 9.0 mg/cm 2 or less of a carbon catalyst; and a second layer which is arranged between the electrolyte membrane and the first layer in the battery, and which contains 0.002 mg/cm 2 or more and 0.190 mg/cm 2 or less of platinum.
1. A cathode of a battery including an electrolyte membrane, the cathode comprising:
a first layer which contains 0.3 mg/cm 2 or more and 9.0 mg/cm 2 or less of a carbon catalyst; and
a second layer which is arranged between the electrolyte membrane and the first layer in the battery, and which contains 0.002 mg/cm 2 or more and 0.190 mg/cm 2 or less of platinum,
wherein the carbon catalyst contains iron,
wherein the carbon catalyst exhibits a weight reduction rate at 200° C. to 1,200° C. of 12.0 wt % or less measured by thermogravimetric analysis in a nitrogen atmosphere, and
wherein the carbon catalyst has a carbon structure that exhibits, in X-ray absorption fine structure analysis of a K absorption edge of the iron, the following (a) and/or (b):
(a) a ratio of a normalized absorbance at 7,130 eV to a normalized absorbance at 7,110 eV is 7.0 or more; and
(b) a ratio of a normalized absorbance at 7,135 eV to a normalized absorbance at 7,110 eV is 7.0 or more.
2. The cathode according to claim 1 , wherein the carbon catalyst has a content of iron of 0.01 wt % or more measured by inductively-coupled plasma mass spectrometry.
3. The cathode according to claim 1 , wherein the carbon catalyst exhibits a nitrogen atom content of 1.0 wt % or more measured by elemental analysis based on a combustion method.
4. The cathode according to claim 1 , wherein the carbon catalyst exhibits a ratio of a nitrogen atom content to a carbon atom content of 1.1% or more measured by elemental analysis based on a combustion method.
5. The cathode according to claim 1 , wherein the carbon catalyst contains iron and a metal other than the iron.
6. The cathode according to claim 1 ,
wherein the first layer contains an electrolyte material, and
wherein the first layer has a ratio of a weight of the electrolyte material to a remaining weight, obtained by subtracting the weight of the electrolyte material from a weight of the first layer, of 0.30 or more.
7. The cathode according to claim 1 ,
wherein the second layer contains an electrolyte material, and
wherein the second layer has a ratio of a weight of the electrolyte material to a remaining weight, obtained by subtracting the weight of the electrolyte material from a weight of the second layer, of 0.05 or more.
8. The cathode according to claim 1 , wherein the cathode has a ratio of a content of the platinum in the second layer to a content of the carbon catalyst in the first layer of 20.00 wt % or less.
9. The cathode according to claim 1 , wherein the first layer and/or the second layer contains an electrolyte material having an EW value of 300 or more and 1,100 or less.
10. A membrane electrode assembly, comprising the cathode of claim 1 , an anode, and an electrolyte membrane arranged between the cathode and the anode.
11. A battery, comprising the cathode of claim 1 , or a membrane electrode assembly, comprising the cathode, an anode, and an electrolyte membrane arranged between the cathode and the anode.
12. The battery according to claim 11 , wherein the battery is a fuel cell.