Electrolyte compositions
An electrolyte for a flow cell battery is provided. The electrolyte includes a concentration of chromium ions that is greater than the concentration of iron ions.
1. A redox flow cell comprising:
a pair of electrodes disposed in separate half-cell compartments;
a porous or ion-selective membrane separating the half-cell compartments; and an
electrolyte that is flowed through the half-cell compartments, wherein the electrolyte comprises FeCl 2 and/or FeCl 3 and CrCl 3 and/or CrCl 2 in aqueous HCI,
wherein a concentration of chromium ions from CrCl 3 and CrCl 2 is greater than a concentration of iron ions from FeCl 2 and FeCl 3 , and a ratio of the concentration of chromium ions to the ratio of iron ions is greater than about 1.1.
2. The redox flow cell of claim 1 , wherein the ratio of chromium ions to iron ions is between 1.1 to 10.
3. The redox flow cell of claim 1 , wherein the ratio of chromium ions to iron ions is greater than about 1.1.
4. The redox flow cell of claim 1 , wherein the ratio of chromium ions to iron ions is between 1.1 and 2.0.
5. A method of reducing hydrogen production in a redox flow cell, the redox flow cell comprising a pair of electrodes disposed in separate half-cell compartments; a porous or ion-selective membrane separating the half-cell compartments; and an electrolyte that is flowed through the half-cell compartments,
wherein the electrolyte comprises FeCl 2 and/or FeCl 3 and CrCl 3 and/or CrCl 2 in aqueous HCI, the method comprising: increasing a total concentration of chromium ions from CrCl 3 and/or CrCl 2 in the electrolyte such that the total concentration of chromium ions from CrCl 3 and/or CrCl 2 in the electrolyte is greater than a total concentration of iron ions from FeCl 2 and FeCl 3 , and a ratio of the concentration of chromium ions to the ratio of iron ions is greater than about 1.1.
6. The method of claim 5 , wherein the ratio of chromium ions to iron ions is between 1.1 to 10.
7. The method of claim 5 , wherein the ratio of chromium ions to iron ions is greater than about 1.1.
8. The method of claim 5 , wherein the ratio of chromium ions to iron ions is between 1.1 and 2.0.