Method for electrochemical gas separation

A method for separating a Lewis acid gas from a fluid mixture comprising the Lewis acid gas, the method comprising:

• contacting the fluid mixture with:
• an electroactive species in a reduced state;
• a non-aqueous electrolyte;
• and
• a stabilizing additive,
• to form an anion adduct between the Lewis acid gas and the electroactive species in the reduced state,
• wherein the electroactive species comprises:
• an oxidized state, and
• at least one reduced state wherein the electroactive species bonds with the Lewis acid gas to form the anion adduct,
• wherein the stabilizing additive comprises a polymeric hydrogen-bond donor, and
• wherein the stabilizing additive is present in an effective amount to
• kinetically favor the forming of the anion adduct from the reduced electroactive species and the Lewis acid gas,
• thermodynamically favor the forming of the anion adduct in a thermodynamic equilibrium between the anion adduct and the reduced electroactive species, or
• kinetically favor the forming of the anion adduct from the reduced electroactive species and thermodynamically favor the forming of the anion adduct in the thermodynamic equilibrium between the anion adduct and the reduced electroactive species.