Abstract Rechargeable magnesium battery (RMB) is gaining attention as a promising alternative to lithium‐ion batteries, offering advantages such as low cost and high theoretical capacity of magnesium metal anodes. Yet, realizing stable, high‐voltage RMB full cells remains a considerable challenge. In this study, a full‐cell configuration is explored combining a vanadium oxide (VO 2 ) cathode with a weakly coordinating anion‐based electrolyte. While encouraging performance is observed in half‐cell setups, translating it into full‐cell operation proves complex, particularly at elevated temperatures. At 60 °C, the initial discharge capacity of 77 mAh g −1 decreases notably to 28 mAh g −1 in the second cycle, whereas performance at 30 °C remains more stable ≈25 mAh g −1 . Three‐electrode measurement suggests increasing overpotentials at the Mg anode as a key factor in the capacity degradation. Further analysis points to issues such as uneven Mg plating/stripping, surface pitting, and minor vanadium dissolution, contributing to impedance growth and cross‐over effects. These are linked to cathode–electrolyte side reactions, particularly under high‐voltage. Overall, the results emphasize the importance of developing stable interphases to enhance the long‐term performance of RMB full cells, especially at elevated temperatures.
Setiawan et al. (Mon,) studied this question.