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 V⁴⁺ to V³⁺ under ambient conditions, thus achieving a remarkably high-purity V³⁺ 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.