Lithium microstructures that form at the lithium surface can create short circuits and lead to catastrophic battery failure – a phenomenon which led ANSTO researchers to use small-angle and ultra-small-angle neutron scattering techniques to better study the complex structures.
To cater to next-generation technologies, the energy density of lithium batteries must increase. The problem is that while replacing common electrodes with pure lithium metal achieves this, the associated lithium microstructures increase the battery’s susceptibility to failure.
“It is important to understand how and why these detrimental lithium structures form in order to prevent them from forming and ultimately enable us to use these types of higher energy batteries,” lead scientist Professor Vanessa Peterson said.
Lithium microstructures come in different forms, including ‘whiskers,’ ‘moss,’ and ‘dendrites.’ Whiskers resemble tiny needles, moss looks like a porous layer, and dendrites are long, thin structures – and it is these ‘pointy’ structures that cause the most trouble, the researchers say.
Using small-angle and ultra-small-angle neutron scattering (SANS and USANS) techniques afforded the researchers a more precise and less complicated way to analyse the structure of deposited lithium compared to methods like X-ray imaging, microscopy, or gas adsorption.
“We observed that the surface area and interfacial distances of deposited lithium change in complex ways depending on the history of the battery’s use,” Professor Peterson said.
“This research opens the door for future investigations to explore how factors like the amount of electric current, charging time, and the cyclic process of lithium deposition and dissolution impact the surface area and the distances between interfaces within deposited lithium.
“Understanding these factors is crucial for addressing the challenges associated with lithium dendrite growth in LMB technology,” she added.
The method also allowed the researchers to understand the size and shape of the lithium structures inside a battery without taking it apart. “This information helped us design a symmetrical pouch cell that was ideal for studying the changes in the lithium that gets deposited inside it.”
The research has been published in Advanced Energy Materials.
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