Protonic ceramic electrochemical cells (pcecs) comprising a contact material for an oxygen electrode, and related pcec stacks and methods of producing hydrogen gas

A protonic ceramic electrochemical cell (PCEC) stack, comprising:

• at least one PCEC including an oxygen electrode, a hydrogen electrode, a proton-conducting ceramic electrolyte between the hydrogen electrode and one side of the oxygen electrode, and a contact material adjacent to another side of the oxygen electrode;
• at least one additional PCEC adjacent to the at least one PCEC, the at least one additional PCEC including an additional oxygen electrode, an additional hydrogen electrode, an additional proton-conducting ceramic electrolyte between the additional hydrogen electrode and one side of the additional oxygen electrode, and an additional contact material adjacent to another side of the additional oxygen electrode;
• and
• an interconnect between the contact material of the at least one PCEC and the additional hydrogen electrode of the at least one additional PCEC,
• wherein at least one of the contact material and the additional contact material comprises a chemical formula of LaMxN1−xO3−δ, wherein M and N are independently selected from a transition metal;
• x is a real number in a range of 0≤x≤1;
• and δ is an oxygen deficiency.

A method of producing hydrogen gas, comprising:

• feeding steam into a protonic ceramic electrochemical cell (PCEC) comprising:
• an oxygen electrode configured to produce oxygen gas from the steam;
• a hydrogen electrode configured to produce hydrogen gas from the steam;
• a proton-conducting ceramic electrolyte between the hydrogen electrode and one side of the oxygen electrode;
• and
• a contact material in direct contact with another side of the oxygen electrode and comprising a chemical formula of LaMxN1−xO3−δ, wherein each of M and N is independently a transition metal;
• x is a real number in a range of 0≤x≤1;
• and 6 is an oxygen deficiency;
• and
• applying a potential difference between the oxygen electrode and the hydrogen electrode of the PCEC to produce the hydrogen gas from the steam.