US Patent 9647290 Electrolyte for redox flow battery and redox flow battery

Provided is an electrolyte for a redox flow battery, the electrolyte allowing suppression of generation of precipitate during a battery reaction. In the electrolyte for a redox flow battery, the total concentration of impurity element ions contributing to generation of precipitate during a battery reaction is 220 mass ppm or less. In a case where the impurity element ions contributing to generation of precipitate include metal element ions, the total concentration of the metal element ions may be 195 mass ppm or less. In a case where the impurity element ions contributing to generation of precipitate include non-metal element ions, the total concentration of the non-metal element ions may be 21 mass ppm or less.