Electrochemical desalination system with coupled electricity storage

A method, comprising:

• providing an electrochemical desalination battery unit comprising:
• at least one water reservoir comprising an input and an output, wherein water in the at least one water reservoir is reduced below a threshold concentration during a desalination operation mode;
• at least one negative-ion redox electrode comprising a first solution of a first electrolyte material and configured to accept, and have a reversible redox reaction with, at least one negative ion in the water;
• at least one positive-ion redox electrode comprising a second solution of a second electrolyte material and configured to accept, and have a reversible redox reaction with, at least one positive ion in the water;
• a cation-exchange membrane disposed between the at least one negative-ion redox electrode and the water reservoir;
• and
• an anion-exchange membrane disposed between the at least one positive-ion redox electrode and the water reservoir;
• transporting water having a first salinity into the water reservoir;
• discharging the battery unit to provide water having a second salinity that is lower than the first salinity;
• and
• removing the water having the second salinity from the battery unit.

A reversible desalination and energy storage system comprising:

• a central reservoir comprising a first electrolyte solution, an input and an output, wherein the first electrolyte solution has a first pH;
• at least one negative-ion redox electrode comprising a second electrolyte solution and configured to accept, and have a reversible redox reaction with, at least one negative ion in the first electrolyte solution, wherein the second electrolyte solution has a second pH;
• at least one positive-ion redox electrode comprising a third electrolyte solution and configured to accept, and have a reversible redox reaction with, at least one positive ion in the first electrolyte solution, wherein the third electrolyte solution has a third pH and the first, second, and third pH is between and including 3-10;
• a cation-exchange membrane disposed between the at least one negative-ion redox electrode and the central reservoir;
• and
• an anion-exchange membrane disposed between the at least one positive-ion redox electrode and the central reservoir.