The findings highlight new possibilities for magnesium batteries

Magnesium batteries have long been considered a potentially safer and less expensive alternative to lithium-ion batteries, but previous versions have been severely limited in the power they deliver.

Researchers from the University of Houston and the Toyota Research Institute of North America (TRINA) report in Nature Energy who developed a new cathode and electrolyte – previously the limiting factors for a high-energy magnesium battery – to demonstrate a magnesium battery capable of operating at room temperature and delivering a power density comparable to that offered by ion batteries of lithium.

As the need for network-scale energy storage and other applications becomes more pressing, researchers have sought cheaper and more readily available alternatives to lithium.

Magnesium ions hold twice the charge of lithium, despite having a similar ion radius. As a result, the dissociation of magnesium from electrolytes and its diffusion into the electrode, two essential processes that occur in classical intercalation cathodes, are slow at room temperature, leading to low power performance.

One approach to address these challenges is to improve chemical reactions at elevated temperatures. The other gets around the difficulties by storing the magnesium cation in its complex forms. Neither approach is practical.

Yan Yao, Cullen Professor of Electrical and Computer Engineering at the University of Houston and corresponding co-author of the paper, said the groundbreaking results come from combining both an organic quinone cathode and a novel cluster-based electrolyte solution. of boron to measure.

“We demonstrated heterogeneous enolization redox chemistry to create a cathode that is unhindered by ion dissociation and solid-state diffusion challenges that have prevented magnesium batteries from operating efficiently at room temperature,” said Yao. “This new class of redox chemistry bypasses the need for solid-state intercalation while storing exclusively magnesium, instead of its complex shapes, creating a new paradigm in magnesium battery electrode design.”

Yao, who is also a principal investigator at the Texas Center for Superconductivity at UH (TcSUH), is a leader in the development of multivalent metal ion batteries. His group recently published a review article in Nature Energy on the roadmap to improve multivalent batteries.

TRINA researchers have made enormous progress in the field of magnesium batteries, including the development of efficient and highly recognized electrolytes based on boron cluster anions. However, these electrolytes had limitations in supporting high battery cycle rates.

“We had clues that electrolytes based on these weakly coordinating anions may in principle have the potential to support very high cycle rates, so we worked to modify their properties,” said Rana Mohtadi, a principal scientist in the research department. on the materials of TRINA and corresponding co-author. “We addressed this problem by turning our attention to the solvent in order to reduce its binding to the magnesium ions and improve the mass transport kinetics.”

“We were fascinated by the fact that the modified electrolyte-plated magnesium remained smooth even at extremely high cycle rates. We believe this unveils a new aspect in the electrochemistry of magnesium batteries.”

The work is in part a continuation of earlier efforts described in 2018 in Joule and involved many of the same researchers. In addition to Yao and Mohtadi, co-authors include early authors Hui Dong, formerly a member of Yao’s lab and now a postdoctoral fellow at the University of Texas at Austin, and Oscar Tutusaus of TRINA; Yanliang Liang and Ye Zhang of UH and TcSUH; and Zachary Lebens-Higgins and Wanli Yang of Lawrence Berkeley National Laboratory. Lebens-Higgins is also affiliated with Binghamton University.

“The new battery is nearly two orders of magnitude higher than the power density achieved by previous magnesium batteries,” said Dong. “The battery was able to continue running for over 200 cycles with approximately 82% retention capacity, showing high stability. We can further improve cycling stability by adapting the membrane properties with greater trapping capacity. intermediate “.

Tutusaus said the work suggests the next steps towards high-performance magnesium batteries.

“Our findings set the direction for the development of high-performance cathode materials and electrolyte solutions for magnesium batteries and bring to light new possibilities for using energy-dense metals for rapid energy storage,” he said. .