The electrode catalyst ink for a water electrolysis cell includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The Hansen solubility parameter distance R.sub.a1 between the solvent and the catalyst is 15.0 MPa.sup.½ or more and less than 20.5 MPa.sup.½. The Hansen solubility parameter distance R.sub.a2 between the solvent and the organic polymer is 10.0 MPa.sup.½ or more and 14.0 MPa.sup.½ or less.

The electrode catalyst ink for a water electrolysis cell includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The Hansen solubility parameter distance R.sub.a1 between the solvent and the catalyst is 15.0 MPa.sup.½ or more and less than 20.5 MPa.sup.½. The Hansen solubility parameter distance R.sub.a2 between the solvent and the organic polymer is 10.0 MPa.sup.½ or more and 14.0 MPa.sup.½ or less.

An object of the present disclosure is to suppress mixing of gases generated during an operation when supply of electric power is stopped, to thereby shorten the time required for restarting after the electric power is stopped. An electrolysis system of the present disclosure includes an electrolyzer including an electrolytic cell in which an anode and a cathode are overlapped with each other having a diaphragm interposed therebetween, and a liquid surface level control unit which is operated when an electric conduction to the electrolyzer is stopped to adjust a liquid surface level of an electrolytic solution in the electrolytic cell.

An object of the present disclosure is to suppress mixing of gases generated during an operation when supply of electric power is stopped, to thereby shorten the time required for restarting after the electric power is stopped. An electrolysis system of the present disclosure includes an electrolyzer including an electrolytic cell in which an anode and a cathode are overlapped with each other having a diaphragm interposed therebetween, and a liquid surface level control unit which is operated when an electric conduction to the electrolyzer is stopped to adjust a liquid surface level of an electrolytic solution in the electrolytic cell.

Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. That substrate may be in nanobar form that conforms to an orientation imparted by a magnetic field or an electric field applied before or during the converting. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.

Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. That substrate may be in nanobar form that conforms to an orientation imparted by a magnetic field or an electric field applied before or during the converting. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.

The electrode catalyst ink includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The solvent includes a first solvent, a second solvent, and a third solvent. The third solvent has a boiling point higher than a boiling point of the first solvent and higher than a boiling point of the second solvent. The Hansen solubility parameter distance R.sub.a1 [MPa.sup.1/2] between the third solvent and the catalyst and the Hansen solubility parameter distance R.sub.a2 [MPa.sup.1/2] between the third solvent and the organic polymer satisfy a relationship of 2.08R.sub.a1−16.0≤R.sub.a2≤2.08R.sub.a1−13.5.

The electrode catalyst ink includes a catalyst including a layered double hydroxide, an organic polymer, and a solvent. The solvent includes a first solvent, a second solvent, and a third solvent. The third solvent has a boiling point higher than a boiling point of the first solvent and higher than a boiling point of the second solvent. The Hansen solubility parameter distance R.sub.a1 [MPa.sup.1/2] between the third solvent and the catalyst and the Hansen solubility parameter distance R.sub.a2 [MPa.sup.1/2] between the third solvent and the organic polymer satisfy a relationship of 2.08R.sub.a1−16.0≤R.sub.a2≤2.08R.sub.a1−13.5.

One aspect of the present invention provides a sodium hydroxide production device, which includes: a first tank configured to store a sodium salt including two or more sodium ions in a molecule; a first electrolysis unit including a first anode chamber and a first cathode chamber which are partitioned by a first separator; and a water supply unit configured to supply water to the first tank and the first cathode chamber, wherein the first tank, a pipe configured to supply an aqueous sodium salt solution produced in the first tank to the first anode chamber, the first anode chamber, and a pipe configured to supply a material produced in the first anode chamber to the first tank constitute a closed loop, and a sodium hypochlorite production device including the same.

One aspect of the present invention provides a sodium hydroxide production device, which includes: a first tank configured to store a sodium salt including two or more sodium ions in a molecule; a first electrolysis unit including a first anode chamber and a first cathode chamber which are partitioned by a first separator; and a water supply unit configured to supply water to the first tank and the first cathode chamber, wherein the first tank, a pipe configured to supply an aqueous sodium salt solution produced in the first tank to the first anode chamber, the first anode chamber, and a pipe configured to supply a material produced in the first anode chamber to the first tank constitute a closed loop, and a sodium hypochlorite production device including the same.