Conductive, anti-corrosive magnesium titanium oxide material
A fuel cell bipolar plate (BPP) includes a metal substrate having a bulk portion and a surface portion comprising an anticorrosive, conductive material having oxygen vacancies and a formula (I): MgTi 2 O 5-δ (I), where δ is any number between 0 and 3 optionally including a fractional part denoting the oxygen vacancies, the material having an electronic conductivity of about 2-10 S/m at room temperature in an ambient environment.
1. A fuel cell bipolar plate comprising:
a metal substrate having:
a bulk portion; and
a surface portion comprising an anticorrosive, conductive, non-stoichiometric material having oxygen vacancies and a formula (I):
MgTi 2 O 5-δ (I),
where δ is a number between 0 and 3 including a fractional part denoting the oxygen vacancies, the non-stoichiometric material having an electronic conductivity of about 2-10 S/m at room temperature in an ambient environment.
2. The bipolar plate of claim 1 , wherein a static corrosion current density of the bipolar plate is less than about 1 μA cm −2 at pH of 2 at a temperature of about 0 to 80° C.
3. The bipolar plate of claim 1 , wherein an Mg/Ti ratio of the material is a number in a range between 0.3 to 0.6.
4. The bipolar plate of claim 1 , wherein the material has an activation energy of about 0.13 eV in a temperature range between 25° C. to 80° C.
5. The bipolar plate of claim 1 , wherein the material has a crystalline structure.
6. The bipolar plate of claim 5 , wherein the structure includes at least one Ti atom with five bonds to oxygen atoms.
7. A proton-exchange-membrane fuel cell bipolar plate comprising:
a metal substrate having a bulk portion and a surface portion either one of which includes an anticorrosive, conductive non-stoichiometric material having oxygen vacancies and a formula (I):
MgTi 2 O 5-δ (I),
where δ is a number between 0 and 3 including a fractional part and denoting oxygen vacancies,
the non-stoichiometric material having a nominal chemical composition of about 33 mol % MgO and 66 mol % of a mixture of TiO and TiO 2 .
8. The bipolar plate of claim 7 , wherein an Mg/Ti ratio is a number in a range between 0.3 to 0.6.
9. The bipolar plate of claim 7 , wherein a static corrosion current density of the bipolar plate is less than about 1 μA cm −2 at pH of 2 at a temperature of about 0 to 80° C.
10. The bipolar plate of claim 7 , wherein the material has an activation energy of about 0.13 eV in a temperature range between 25° C. to 80° C.
11. The bipolar plate of claim 7 , wherein the bulk portion comprises the material.
12. A fuel cell comprising:
a bipolar plate having a metal substrate including a bulk portion and a surface portion comprising an anticorrosive, conductive material having oxygen vacancies and a formula (I):
MgTi 2 O 5-δ (I),
where
δ is any number between 0 and 3 including the fractional part denoting the oxygen vacancies,
the material having an electronic conductivity of about 2-10 S/m at room temperature in ambient environment.
13. The fuel cell of claim 12 , wherein static corrosion current density of the bipolar plate is less than about 1 μA cm −2 at pH of 2 at a temperature of about 0 to 80° C.
14. The fuel cell of claim 12 , wherein an Mg/Ti ratio of the material is a number in a range between 0.3 to 0.6.
15. The fuel cell of claim 12 , wherein the fuel cell is an anion exchange membrane fuel cell (AEMFC).