<p>Electrolyte protection against oxygen is a practical strategy to extend the service life of vanadium redox flow batteries, and this study compares two common approaches in a three-cell stack: protecting the electrolyte with a paraffin blanket versus removing oxygen via nitrogen injection. Nitrogen injection provides markedly better performance stability than paraffin shielding. This improvement is observed as 502 mAh more capacity and 28.1% more capacity retention after 100 cycles for the nitrogen-protected sample. The charge–discharge profiles of the nitrogen-protected electrolyte show tighter clustering and less performance dispersion. At the end of cycling, the average oxidation state value of the paraffin sample shows a greater positive deviation of + 3.5 than the nitrogen-containing sample, indicating a greater oxidative imbalance in it. The energy density curve for the paraffin-protected stack exhibits a concave-upward behavior that is substantially mitigated under nitrogen protection, while coulombic efficiency data indicate that nitrogen suppresses the reaction between V²⁺ and oxygen, especially in early cycles. Cyclic voltammetry further suggests less pronounced kinetic limitations for electron transfer in the nitrogen-containing electrolyte relative to the paraffin-containing one, pointing to reduced parasitic side reactions. Replacing paraffin shielding with nitrogen injection significantly reduces electrolyte–oxygen interactions, thereby boosting performance stability in operational stack configurations.</p>