Researchers at the University of Illinois at Chicago have taken a significant step toward the development of a battery that could outperform the lithium-ion technology used in electric cars such as the Chevy Volt. They have shown they can replace the lithium ions, each of which carries a single positive charge, with magnesium ions, which have a plus-two charge, in battery-like chemical reactions, using an electrode with a structure like those in many of today's devices.
â€œBecause magnesium is an ion that carries two positive charges, every time we introduce a magnesium ion in the structure of the battery material we can move twice as many electrons,â€ says Jordi Cabana, UIC assistant professor of chemistry and principal investigator on the study. â€œWe hope that this work will open a credible design path for a new class of high-voltage, high-energy batteries,â€ Cabana continued.
The research is part of the Joint Center for Energy Storage Research, a Department of Energy Innovation Hub led by Argonne National Laboratory, that aims to achieve revolutionary advances in battery performance. Every battery consists of a positive and negative electrode and an electrolyte. The electrodes exchange electrons and ions, which are usually of positive charge. Only the ions flow through the electrolyte, which is an electric insulator so as to force the electrons to flow through the external circuit to power the vehicle or device.
To recharge the battery, the exchange is reversed. But the chemical reaction is not perfectly efficient, which limits how many times the battery can be recharged. â€œThe more times you can do this back and forth, the more times you will be able to recharge your battery and still get the use of it between charges,â€ Cabana said. â€œIn our case, we want to maximize the number of electrons moved per ion, because ions distort the structure of the electrode material when they go in or leave. The more the structure is distorted, the greater the energy cost of moving the ions back, the harder it becomes to recharge the battery.â€
â€œLike a parking garage, there are only so many spaces for the cars,â€ Cabana said. â€œBut you can put a car in each space with more people inside without distorting the structure.â€ Having established that magnesium can be reversibly inserted into electrode materialâ€™s structure brings us one step closer to a prototype, stated Cabana.
â€œItâ€™s not a battery yet, itâ€™s a piece of a battery, but with the same reaction you would find in the final device,â€ concluded Cabana.
Chunjoong Kim, postdoctoral research associate, UIC chemistry, was first author of the paper. Tanghong Yi, postdoctoral research associate, and Ryan Bayliss, postdoctoral research associate, UIC chemistry; Patrick Phillips, research assistant professor, and Robert Klie, associate professor, UIC physics; Baris Key, Sang-Don Han, Zhengcheng Zhang and Anthony Burrell, Argonne National Laboratory; Dennis Nordlund, SLAC National Accelerator Laboratory; Meinan He, Argonne and Worcester Polytechnic Institute, Worchester, Massachusetts; and Young-Sang Yu, post doctoral research fellow, UIC chemistry and Lawrence Berkeley National Laboratory, were co-authors on the paper.
The Joint Center for Energy Storage Research (JCESR), JCESR is a major partnership that integrates researchers from many disciplines to overcome critical scientific and technical barriers and create new breakthrough energy storage technology. Led by the U.S. Department of Energyâ€™s Argonne National Laboratory, partners include national leaders in science and engineering from academia, the private sector, and national laboratories. Their combined expertise spans the full range of the technology-development pipeline from basic research to prototype development to product engineering to market delivery. JCESR is a DOE Energy Innovation Hub supported by DOEâ€™s Office of Science.
Additional support was provided by the Advanced Light Source DOE Office of Science awards DE-AC02-05CH11231, and DE-SC0012583. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. DOE, Office of Science, DE-AC02-76SF00515. The UIC JEOL JEM-ARM 200CF is supported by an MRI-R^2 grant from the National Science Foundation (Grant No. DMR-0959470).