Principle and Characteristic
The active substance in vanadium flow battery is vanadium ion of different valences. There are VO2 +, VO2 +, V3 +, V2 + in the aqueous solution of sulfuric acid. The active electric pair of VO2 +/VO2 + are present in the positive electrolyte, and the active electric pair of V3+/V2+ are present in the negative electrolyte. The reaction is as bellows.
When charging, the VO2+ of the positive electrode loses electrons to form VO2+, and the V3+ of negative electrode gains electrons to form V2+. The electrons form the electric current from the positive electrode to the negative electrode through an external circuit; and H+ passes the charge to the negative electrode from the positive electrode through the ion exchange membrane to form a closed loop. The discharging is realized in the opposite process.
Vanadium flow battery is proven to be the preferred technology applicable to large-scale power storage, which has the following characteristics:
○Running at normal temperature and atmospheric pressure safely;
• Active substance is the aqueous solution of vanadium ions, which does not burn or explode.
•Even in the worst case when positive and negative active substances are intermixed due to exchange -membrane ruptured, there is no concern on fire or explosion.
•The heat can be effectively discharged and the battery thermal management is very simple.
•Desirable consistency of cells in the assmbled battery systems.
○ Power and capacity can be independently designed, as makes the battery can be scaled up flexibly;
•Capacity recovery can be achieved through on-line or off-line electrolyte regeneration.
• Large storage capacity ranging from 10kWh to hundreds of MWh;
•Power output ranges from kW to hundreds of MW;
○ Desirable battery uniformity, capable of deep discharge, long service life, making it durable battery;
•In the process of charge and discharge, the electrode material provides only the interface without participating in the reaction, so it can maintain long-term stability.
•In the process of charge and discharge, there is no phase transformation.
•Deep charge and deep discharge have no adverse impact on battery performance.
•The impact of temperature on the capacity is recoverable.
○ Resource conserving, environment-friendly, safe and reliable, making it green battery;
•During the use of the battery, the vanadium is only subjected to valence changes, and will not be consumed, so it can be permanently recycled to conserve resource.