Flash Production of High‐Purity V 3.5+ Electrolyte via Electron Beam‐Induced Radiolysis Under Ambient Conditions

The quest for high‐performance vanadium redox flow batteries has long been hindered by the time‐consuming and impurity‐prone synthesis of mixed‐valence vanadium electrolytes (V 3.5+ ). Distinct from the existing synthetic approaches, we develop an effective, catalyst‐free strategy to produce V 3.5+ electrolytes only in minutes by using electron‐beam irradiation. We show water radiolysis can generate a burst of hydrated electrons and reductive radicals that rapidly convert V 4+ to V 3+ under ambient conditions, thus achieving a remarkably high‐purity V 3+ generation rate of 0.65 mol·L −1 ·h −1 , exceeding the reported values from existing methods. In addition, the resulting electrolyte unlocks outstanding battery performance, delivering a coulombic efficiency of 97.92%, an energy efficiency of 85.05% at 100 mA cm −2 , and a slow capacity degradation of 0.201% per cycle over 120 cycles. Owing to its simplicity, high‐throughput, and scalability radiation‐driven approach provides a promising pathway toward efficient, sustainable, and cost‐effective energy storage, making it a competitive and transformative technique for advanced electrolyte fabrication.