A mathematical model paves the way for the development of a new generation of batteries

More powerful, faster to recharge, lighter … Compared to lithium-ion batteries, lithium-metal batteries are more reliable. However, despite many trials, technical hurdles still stand in their way. Team of scientists from Stanford’s School of Earth, Energy & Environmental Sciences So he decided to take the problem from a more mathematical angle.

If the lithium-metal battery, a close relative of the lithium-ion battery, has not yet stolen the show, it is especially due to dendrites. In a battery, dendrites are small excitations that form during lithium deposition during discharge and recharging cycles. As they grow to the point where the anode and cathode (the “+” and “-” terminals of a circuit) connect, they can cause performance loss, overheating or short circuits. Until now, these popular dendrites have apparently controlled the commercial growth of lithium-metal batteries.

Many laboratory experiments are aimed at solving this problem, with varying degrees of success. However, scientists say that this method of working in the laboratory will take a long time to work and the results will be difficult to interpret. At this point, the researchers decided to focus on the theoretical aspect. They worked on a mathematical model based on the physics and chemistry involved in the formation of dendrites. They presented their results Journal of the Electrochemical Society.

“ Much research has been devoted to product design and testing of complex battery systems, and generally Weiu-led mathematical structures have often been overlooked in this endeavor. One of the co-authors of the study is Daniel Dartakovsky, Professor of Stanford Energy Resource Engineering. A statement Of the establishment. The mathematical model developed by the scientists aims to represent the mechanisms by which a lithium-metal battery works, especially the transport of lithium ions through internal electric fields and the electrolyte material.

The aim is to provide theoretical indications to other researchers’ groups that could carry out more targeted experiments to increase battery life. ” It is our hope that these insights from our study will allow other researchers to design devices with the right characteristics, reduce testing and error range, and use the test variations they make in the laboratory. “The co-author of the study, Hamdi Theselipi, announced:” As a result, a first study already provides avenues for experimentation. “ This study provides some specific information on the conditions under which dendrites can develop and possible pathways to suppress their development. Hamdi Theselipi is pleased.

Anisotropic materials, keys to future batteries?

The first model presented by scientists expresses an important idea: the use of new electrolytes, especially anisotropic electrolytes, can control or stop the growth of dendrites. An electrolyte is a conductive material that allows ions to move between two electrodes in a battery. To better understand, we need to look at the definition of “anisotropic”.

Anisotropic substances are substances that exhibit different properties depending on their “direction”. ” A classic example of anisotropic material is wood, which is strong in the direction of the grain and is visible as streaks on the wood relative to the direction of the grain. », Refers to Stanford’s School of Earth, Energy & Environmental Sciences. Anisotropic electrolytes, according to mathematicians, regulate the movement of ions to prevent the formation of dendrites. Some liquid crystals or gels in particular have such properties, scientists suggest.

The use of anisotropic substances can take its place in the application of membranes. In fact, one of the approaches currently used to solve the problem of dendrites is to place a membrane to prevent the electrodes from touching each other and short circuit. Separators with holes that allow the rotation of ions in an anisotropic way can find their use there.

However, to confirm these theoretical approaches, it is necessary to wait for other researchers to understand them during their experiments. Meanwhile, a team of scientists is working to create a complete virtual representation of this type of battery. This is called a virtual model ” Digital incarnation of the metal-ion battery system », Or DABS. ” With DABS, we will continue to improve the state-of-the-art technology for these promising energy storage devices. Says Daniel Dartakovsky.

Source: Journal of the Electrochemical Society