NaSICON Prepared by Solution-Assisted Reaction for High-Voltage Aqueous Redox-Flow Batteries

A method for making an ion-exchange membrane, the method comprising:

• (a) combining a first solid comprising sodium, a second solid comprising silicon, and a third solid comprising phosphorus to form a first mixture;
• (b) adding a solution of a zirconium-containing compound to the first mixture to create a second mixture;
• (c) heating the second mixture at a temperature in a range of 30° C. to 100° C. and drying to form a powder;
• and
• (d) applying simultaneous heat and pressure to the powder to form an ion-exchange membrane comprising a ceramic material having a Formula (I):
• wherein x is between 0 and 3.

An aqueous redox flow cell comprising:

• a positive electrode;
• a negative electrode;
• a posolyte compartment containing a posolyte wherein at least a part of the positive electrode contacts the posolyte;
• a negolyte compartment containing a negolyte wherein at least a part of the negative electrode contacts the negolyte;
• and
• an ion-exchange membrane positioned to separate the positive electrode and the posolyte from the negative electrode and the negolyte,
• wherein the ion-exchange membrane comprises a ceramic material having Formula (I):
• wherein x is between 0 and 3, and
• wherein the ceramic material has an area % of a glassy phase of less than 15% when determined using scanning electron microscopy imaging analysis.

An ion-exchange membrane comprising:

• a ceramic material having Formula (II):
• wherein M is selected from the group consisting of Mg, Ca, Sc, Yb, Co, Zn, La, Ce, and mixtures thereof,
• wherein a is between 1 and 6, and
• wherein b is between 1 and 2, and
• wherein x is between 0 and 3, and
• wherein the ceramic material has an area % of a glassy phase of less than 15% when determined using scanning electron microscopy imaging analysis.