Researchers have developed a new mathematical model that combines the physics and chemistry of very promising lithium-metal batteries. Consequently, this has led to feasible, novel solutions to an issue that has been linked to degradation and failure.
As next-generation energy storage technologies, lithium-metal batteries show a lot of promise. They have a higher energy capacity, charge faster, and are lighter than lithium-ion batteries. To date, though, commercial use of such batteries has been limited due to concerns over their potential for overheating and catching fire. The production of “dendrites,” thin, metallic tree-like structures that sprout as lithium metal accumulates on electrodes inside the battery, is one of the main reasons.
Stanford scientists have now devised a mathematical model that revealed that changing the electrolytes – the liquid through which lithium ions travel between the two electrodes in a battery – to ones with specific qualities could reduce or even stop dendrite growth.
The research specifically calls for novel electrolyte design tactics that involve targeting anisotropic materials, which have varied characteristics in different orientations. An example of such a material is wood, which is stronger along the direction of the grain than against the grain. These materials could finetune the complicated interplay between ion transport and interfacial chemistry in anisotropic electrolytes, preventing the accumulation that leads to dendrite development. According to the researchers, some liquid crystals and gels exhibit these desired features.
Battery separators (membranes that prevent electrodes at opposite ends of the battery from contacting and short-circuiting) are another solution that was a huge aspect of the study. New types of separators with pores that allow lithium ions to move back and forth through the electrolyte in an anisotropic manner could be developed.
“Our study’s aim is to help guide the design of lithium-metal batteries with longer life span,” said the study lead author Weiyu Li, a PhD student in energy resources engineering co-advised by Professors Daniel Tartakovsky and Hamdi Tchelepi. “Our mathematical framework accounts for the key chemical and physical processes in lithium-metal batteries at the appropriate scale.”
“This study provides some of the specific details about the conditions under which dendrites can form, as well as possible pathways for suppressing their growth,” said study co-author Tchelepi, a professor of energy resources engineering at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth).