Ionic conductors with wide electrochemical window and current collector for high voltage aqueous electrolyte electrochemical devices

摘要

An electrolyte for an electrochemical device comprises an aqueous salt solution, wherein a sufficient quantity of the salt is dissolved therein for the solution to be saturated; and a water-absorbent polymer. The water-absorbent polymer may be dissolved in the aqueous solution, or may absorb water, optionally swelling in the process. The solution may be an over-saturated aqueous salt solution. The electrolyte, which may be in the form of a gel, may be incorporated into an electrochemical device comprising electrodes. The electrolyte may be made by heating a water-containing liquid to a temperature near and below its boiling point; maintaining the temperature of the liquid whilst adding a water-absorbent polymer to the liquid and dissolving a salt into the liquid until a saturated solution is formed; and cooling the solution to room temperature. An electrolyte comprising a saturated aqueous salt solution without the water-soluble polymer is also claimed. The water absorbent polymer is preferably polyvinyl alcohol, polyvinyl pyrrolidone, polypropylene alcohol or polyethylene glycol. It may be or comprise a super-absorbent polymer, such as a polyacrylate salt, a polyacrylamide, a polysaccharide, a polypeptide, polyacrylonitrile or a polyvinyl alcohol copolymer. The addition of the polymer increases the electrochemical window of the electrolyte.