A Novel Vanadium–Titanium Redox Flow Battery with Enhanced Electrochemical Performance & Greener Alternative

In pursuit of efficient and cost‐effective grid‐scale energy storage solutions, redox flow batteries (RFBs) have emerged as champions by offering a promising solution owing to their design scalability. However, conventional vanadium RFBs are limited by high and volatile material costs. Here, a novel vanadium–titanium RFB (VTRFB) is presented that combines the redox potential of vanadium (V 5+ /V 4+ ) with the low cost and natural abundance of titanium (Ti 3+ /Ti 4+ ). The VTRFB delivers a long‐term performance over more than 500 h (>150 cycles), maintaining ≈100% coulombic efficiency (CE%) and ≈80% voltage (VE%) and energy (EE%) efficiencies. Furthermore, the RFB also reaches an energy density of ≈21.8 Wh L −1 with a stable nominal discharge voltage of 0.9 V. To advance sustainability and green chemistry, the vanadium catholyte is replaced with a BmimCl‐based ionic‐liquid formulation, and a cost‐effective SPEEK membrane is incorporated. Both modifications preserve CE > 90% and VE%/EE% above 50%, demonstrating that the system remains robust even under greener and lower‐cost configurations. This VTRFB design integrates low‐cost materials and high electrochemical performance, representing a significant step toward next‐generation sustainable RFBs.