Revealing the Thermodynamics of Magnesium and Lithium Ion Insertion Chemistry in Ultrafast Discharging Hybrid Rechargeable Batteries
Our experimental results confirm that at low Li+ activities in the electrolyte, Mg2+ insertion dominates and the battery can cycle only below 80 mAh g-1, whereas at high Li+ activities, fast Li+ ionic transport in the entire intercalation range leads to higher voltage, capacity and rate capability. We find that the Mg/Li hybrid rechargeable battery with an APC 0.2 M and LiCl 0.5 M dual-salt electrolyte has a remarkable electrochemical performance. This hybrid battery with optimized insertion chemistry achieves 93.6% capacity retention at 20 C and 87.5% at 30 C at room temperature. Our combined computational and experimental study suggests an effective route to develop new dual-salt hybrid systems with controlled insertion chemistry.
This work has been supported by The Dow Chemical Company and Northwestern-Argonne Institute of Science and Engineering (NAISE).
 J.-H. Cho, M. Aykol, S. Kim, J.-H. Ha, C. Wolverton, K. Y. Chung, K.-B. Kim, and B. -W. Cho, J. Am. Chem. Soc. 2014, 136, 16116.