Redox flow battery

Abstract

A redox flow battery includes a battery cell; a positive electrolyte tank and a negative electrolyte tank configured to store therein a positive electrolyte and a negative electrolyte, respectively; a positive electrolyte circulation path and a negative electrolyte circulation path each configured to allow a corresponding one of the electrolytes to circulate between a corresponding one of the tanks and the battery cell; and a communicating tube including a tube immersed at one open end thereof in the positive electrolyte, stretched at an intermediate portion thereof above levels of both the electrolytes, and immersed at the other open end thereof in the negative electrolyte.

1 . A redox flow battery comprising:
 a battery cell;   a positive electrolyte tank and a negative electrolyte tank;   a positive electrolyte circulation path and a negative electrolyte circulation path each configured to allow an electrolyte to circulate between a corresponding one of the tanks and the battery cell; and   a communicating tube configured to allow an interior of the positive electrolyte tank to communicate with an interior of the negative electrolyte tank,   wherein the communicating tube has one open end located in the interior of the positive electrolyte tank and the other open end located in the interior of the negative electrolyte tank;   a height of an intermediate portion of the communicating tube is higher than a height of the one open end, the intermediate portion being disposed between the one open end and the other open end; and   the height of the intermediate portion of the communicating tube is higher than a height of the other open end.   
     
     
         2 . The redox flow battery according to  claim 1 , wherein the positive electrolyte tank and the negative electrolyte tank each have a top, a bottom, and a side; and
 the communicating tube has
 a first extending portion extending from the one open end to the top of the positive electrolyte tank, 
 the intermediate portion located in an outside region between the positive electrolyte tank and the negative electrolyte tank, and 
 a second extending portion extending from the top of the negative electrolyte tank to the other open end. 
   
     
     
         3 . The redox flow battery according to  claim 2 , wherein the first extending portion has a first end corresponding to the one open end of the communicating tube;
 a distance from the top of the positive electrolyte tank to the first end is greater than a distance from the bottom of the positive electrolyte tank to the first end;   the second extending portion has a second end corresponding to the other open end of the communicating tube; and   a distance from the top of the negative electrolyte tank to the second end is greater than a distance from the bottom of the negative electrolyte tank to the second end.   
     
     
         4 . The redox flow battery according to  claim 3 , further comprising:
 a positive electrolyte stored in the positive electrolyte tank; and   a negative electrolyte stored in the negative electrolyte tank,   wherein the first end is located below a level of the positive electrolyte stored in the positive electrolyte tank;   the first end is located at a distance of h/2 or less from the bottom of the positive electrolyte tank, where h is a height from the bottom of the positive electrolyte tank to the level of the positive electrolyte;   the second end is located below a level of the negative electrolyte stored in the negative electrolyte tank; and   the second end is located at a distance of H/2 or less from the bottom of the negative electrolyte tank, where H is a height from the bottom of the negative electrolyte tank to the level of the negative electrolyte.   
     
     
         5 . The redox flow battery according to  claim 2 , wherein the first extending portion extends substantially in a height direction; and
 the second extending portion extends substantially in the height direction.   
     
     
         6 . The redox flow battery according to  claim 1 , wherein at least a portion of the communicating tube is made of a transparent material to make an interior of the communicating tube visible from outside. 
     
     
         7 . The redox flow battery according to  claim 1 , wherein the communicating tube has a window in a highest region thereof, and the window is made of a transparent material. 
     
     
         8 . The redox flow battery according to  claim 1 , wherein a length L from the one open end to the other open end of the communicating tube is 10 m or less. 
     
     
         9 . The redox flow battery according to  claim 1 , wherein the communicating tube has an inside diameter d of 10 mm or more and 150 mm or less. 
     
     
         10 . The redox flow battery according to  claim 1 , wherein a length L from the one open end to the other open end of the communicating tube is 10 m or less;
 an inside diameter d of the communicating tube is 10 mm or more and 150 mm or less; and   the length L is less than or equal to 100 times the inside diameter d.   
     
     
         11 . The redox flow battery according to  claim 1 , further comprising a gas vent pipe configured to allow air bubbles to escape from inside the communicating tube,
 wherein the gas vent pipe is connected at one end thereof to the communicating tube and connected at the other end thereof to at least one of the positive electrolyte circulation path and the negative electrolyte circulation path.   
     
     
         12 . The redox flow battery according to  claim 1 , further comprising:
 a positive electrolyte stored in the positive electrolyte tank; and   a negative electrolyte stored in the negative electrolyte tank,   wherein the communicating tube is immersed at both ends thereof in the respective electrolytes, and an interior of the communicating tube is filled with the positive electrolyte and the negative electrolyte.   
     
     
         13 . The redox flow battery according to  claim 12 , wherein the height of the intermediate portion of the communicating tube is higher than a level of the positive electrolyte stored in the positive electrolyte tank and a level of the negative electrolyte stored in the negative electrolyte tank. 
     
     
         14 . The redox flow battery according to  claim 12 , wherein at least a portion of the communicating tube is made of a transparent material to make an interior of the communicating tube visible from outside. 
     
     
         15 . The redox flow battery according to  claim 12 , wherein the communicating tube has a window in a highest region thereof, and the window is made of a transparent material.