Electrolyte for redox flow battery and redox flow battery system
An electrolyte for a redox flow battery has a total concentration of arsenic ions and antimony ions of 15 mass ppm or less. In an example of the electrolyte for a redox flow battery, preferably, the concentration of the arsenic ions is 10 mass ppm or less. In another example of the electrolyte for a redox flow battery, preferably, the concentration of the antimony ions is 10 mass ppm or less.
1. An electrolyte for a redox flow battery having arsenic and antimony ions and having a total concentration of arsenic ions and antimony ions of 15 mass ppm or less,
a concentration of vanadium ions of 1 to 3 mol/L,
a concentration of free sulfuric acid of 1 to 4 mol/L,
a concentration of phosphoric acid of 1.0×10 −4 to 7.1×10 −1 mol/L,
a concentration of ammonium of 20 mass ppm or less,
a concentration of silicon of 40 mass ppm or less, and
the vanadium ions have an average valence of 3.3 to 3.7.
2. The electrolyte for a redox flow battery according to claim 1 , wherein the concentration of the arsenic ions is 10 mass ppm or less.
3. The electrolyte for a redox flow battery according to claim 1 , wherein the concentration of the antimony ions is 10 mass ppm or less.
4. A redox flow battery system comprising a redox flow battery to which the electrolyte for a redox flow battery according to claim 1 is supplied.
5. The redox flow battery system according to claim 4 , further comprising;
a pipe for supplying and discharging the electrolyte for a redox flow battery to and from the redox flow battery; and
a transparent portion provided in part of the pipe.