The HIU research group led by Axel Groß has made it on the back cover of the journal Energy & Environmental Science of the Royal Society of Chemistry with its element-specific theory – why battery electrode materials differ in their propensity for growing dendrites. Burning mobile phones or electric cars bursting into flames are caused by the formation of dendrites in batteries. The results could help solve the safety problems with the shrub-like crystal structures that can cause short circuits.
The researchers looked for battery materials that do not form any dendrites at all. While lithium, zinc and sodium batteries often form these spark-inducing structures, magnesium and aluminum batteries are virtually dendrite-free. In order to better understand dendrite formation, they therefore looked for a connection between the self-diffusion barriers of different metals. These barriers are the interfaces that reduce the diffusion of an atom on a surface of the same element and determine how likely it is that metal atoms deposit on electrodes and cause dendrite growth.
By studying the different metals, Axel Groß and his team found that lithium ions have relatively high self-diffusion interfaces, which means that once they have diffused a gradient onto a surface, the lithium ions remain there and form a rough area. The dendrite then branches from this defect. This suggests that dendrite formation is an inherent property of this element. In comparison, metals such as magnesium have a very low self-diffusion barriers and form smooth surfaces, so dendrites occur much less frequently.
The theory was also discussed in a separate news item in Chemistry World:
For more information: pubs.rsc.org/en/Content/ArticleLanding/2018/EE/C8EE01448E