Redox flow battery and method for operating the battery continuously in a long period of time

1. A redox flow battery, comprising:

a battery;

a positive electrolyte tank;

a negative electrolyte tank; and

a pipe, connected to the positive electrolyte tank and the negative electrolyte tank and configured to keep the positive electrolyte tank and the negative electrolyte tank in liquid communication with each other, and having a length-to-diameter ratio (L/D ratio) in the range of about 15 to about 800,

wherein the pipe does not include a valve, and

wherein the battery is in fluid communication with the positive electrolyte tank and the negative electrolyte tank.

2. The redox flow battery according to claim 1 , wherein the pipe is located below the liquid levels of the respective tanks.

3. The redox flow battery according to claim 1 , wherein the L/D ratio of the pipe is in the range of about 80 to about 200, such that the average value of the current efficiency of the redox flow battery is between about 92% and about 93% after 100 cycles of charge/discharge.

4. The redox flow battery according to claim 1 , wherein the pipe is made of at least one material selected from the group consisting of polyvinyl chloride, polypropylene, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, chlorinated polyethylene, chlorinated polypropylene, poly(vinylidene difluoride), polyester, polycarbonate, polyalcohols, polysulfone, polyethersulphone, polyether, polyamide, polyimide, polyphenylene sulfide, poly(ether-ketone), poly(ether-ether-ketone), poly(pathalazinone-ether-ketone), polybenzimidazole, polystyrene, polyisobutylene, and polyacrylonitrile.

5. The redox flow battery according to claim 1 , wherein the pipe is connected to the electrolyte tanks by at least any one method of flange-connection, welding, and adhesion.

6. The redox flow battery according to claim 1 , wherein the pipe is connected to the electrolyte tanks in a form of integral formation.

7. The redox flow battery according to claim 1 , wherein the pipe is coiled around a portion of at least one of the positive electrolyte tank or the negative electrolyte tank.

8. The redox flow battery according to claim 1 , wherein the redox flow battery is a vanadium redox flow battery.

9. A method for operating a redox flow battery, the method comprising:

keeping a positive electrolyte storage tank and a negative electrolyte storage tank in liquid communication with each other through a pipe during operation of the redox flow battery; and

keeping the positive electrolyte storage tank and the negative electrolyte storage tank in communication with the battery;

wherein a length-to-diameter ratio (L/D ratio) of the pipe is in the range of about 15 to about 800, and

wherein the pipe does not include a valve.

10. The method according to claim 9 , wherein the pipe is located below the liquid levels of the respective tanks.

11. The method according to claim 9 , wherein the L/D ratio of the pipe is in the range of about 80 to about 200, such that the average value of the current efficiency of the redox flow battery is between about 92% and about 93% after 100 cycles of charge/discharge.

12. The method according to claim 9 , wherein the pipe is made of at least one material selected from the group consisting of polyvinyl chloride, polypropylene, polyethylene, polytetrafluoroethylene, polyvinylidene fluoride, chlorinated polyethylene, chlorinated polypropylene, poly(vinylidene difluoride), polyester, polycarbonate, polyalcohols, polysulfone, polyethersulphone, polyether, polyamide, polyimide, polyphenylene sulfide, poly(ether-ketone), poly(ether-ether-ketone), poly(pathalazinone-ether-ketone), polybenzimidazole, polystyrene, polyisobutylene, and polyacrylonitrile.

13. The method according to claim 9 , wherein the pipe is connected to the electrolyte storage tanks by at least any one method of flange-connection, welding, and adhesion.

14. The method according to claim 9 , wherein the pipe is connected to the electrolyte storage tanks in a form of integral formation.

15. The method according to claim 9 , wherein the redox flow battery is a vanadium redox flow battery.