Image credit: Kristoferb/CC BY-SA 3.0, via Wikimedia Commons.Developing new technologies for rechargeable batteries that go beyond the current lithium standard—used in everything from mobile phones to electric cars to electrical grid storage—is a hot topic these days. As published in the journal Nature Materials, an international team of researchers has outlined a strategy for designing practical “multivalent batteries” that improve on energy storage capacity and performance.
In lithium-ion batteries, electric current is created by the transfer of lithium ions inside the battery. Because lithium is “monovalent,” a single electron is transferred along with a single ion. By contrast, multivalent batteries employ multivalent metals to achieve the transfer of multiple electrons. This translates to more charge produced by a battery of the same size.
In their proof-of-concept study, the researchers note that inserting multivalent ions into electrode materials has proved an elusive goal. Their new strategy relied on the “chemistry of defects” to unlock the electrochemical activity of known materials—in this case, magnesium and aluminum. A modified version of titanium dioxide was used as an electrode; by deliberately introducing defects into it, high concentrations of microscopic holes were formed—allowing magnesium and aluminum to be inserted.
The research team was comprised of scientists from the University of Bath, France, Germany, Holland and the United States.
"Multivalent batteries are a really exciting direction for battery technology, potentially offering higher charge densities and better performance. New battery technologies are going to be more and more important as we wean ourselves off fossil fuels and adopt greener energy sources,” said Dr. Benjamin Morgan, a member of the chemistry department at the University of Bath. "There are quite a few technical hurdles to overcome, including finding materials that are good electrodes for multivalent ions."
"In the long term, this proof of concept is a possible step towards 'beyond lithium' batteries with superior performance," Morgan added.
