Author: Sajia Athai, Class of 2026

Figure 1. A magnesium-based battery.

From putting AAA alkaline batteries into remotes to rechargeable batteries in Teslas, modern applications require high-energy rechargeable batteries to function efficiently and sustainably. The tubular structure of batteries conceals the inner dynamics of solvent exchange,  the journey of solvent molecules moving in and out of the ion’s solvation shell in electrolytes. Magnesium-based rechargeable batteries offer an alternative: new electrolyte design and energy storage technology using sustainable materials.

Batteries are intricate beyond their material insulation. The transport of magnesium ions is integral to the functionality of the battery. Research conducted by Dr. Nav Nidhi Rajput, a professor specializing in Chemical Engineering at Stony Brook University, and a team of researchers highlights that various battery solvents display slow exchange rates of 0.5 µs to 5 ms, which impacts the efficiency of magnesium ions traveling through the electrolyte. The researchers drafted a model incorporating regions full of organic and inorganic solvents, where organic solvents removed solvent molecules from magnesium ions and inorganic solvents helped transport them. Experimental spectroscopic techniques such as Nuclear Magnetic Resonance, Electrochemical Impedance, Cryogenic X-ray Photoelectron, Molecular Dynamics Simulations, and Density Functional Theory calculations were utilized to observe solvent exchange rates and interaction energies between solvents and ions to determine if a magnesium-based system yields improved results.

A mixture of 0.45 M magnesium bis(trifluoromethylsulfonyl)imide (MgTFSI₂) and 1,2-dimethoxyethane (DME) with a range of cosolvents such as ethers and nitrogen-containing solvents was utilized to yield various mixed-solvent electrolytes. This sample was analyzed for ion behavior and environmental influence to understand how solvent exchange affects the performance of electrolytes. The impacts of viscosity and exchange rates on electrolyte performance were represented through scatter plots, and distribution curves to depict binding energies and ion conductivity. The collected data revealed greater exchange rates of 3.5 ms for DME at 25 °C, magnitudes greater than the suggested lower experimental range of hundreds of pico-seconds.  This delineated that many battery-relevant solvents tested routinely for non-aqueous properties exhibit ultraslow solvent exchange. Greater exchange rates exhibited increased magnesium transport and performance in electrolytes.

Ion behavior and exchange impact mechanical systems similarly to how processes like the sodium-potassium pump affect the biological systems in the human body. The appearances of batteries disguise the solvent exchange and magnesium transport needed to create sustainable energy sources. A magnesium-based system that effectively improves the transport of ions may be the solution to energy storage technology.

Works Cited:

1. Chen, Y., Atwi, R., Nguyen, D. T., Bazak, J. D., Hahn, N. T., Ryu, J., Sears, J. A., Han, K. S., Song, M., Li, Z., Karkamkar, A. J., Hu, J. Z., Zavadil, K. R., Rajput, N. N., Mueller, K. T., & Murugesan, V. (2024). From bulk to interface: solvent exchange dynamics and their role in ion transport and the interfacial model of rechargeable magnesium batteries. Journal of the American Chemical Society, 146(19), 12984–12999. https://doi.org/10.1021/jacs.3c13627.

2. Image taken from https://commons.m.wikimedia.org/wiki/File:Battery-dynamic-color.png.