Battery scientists have been up against a wall with solid state lithium batteries for a while, because of dendrite formation. If they could only find a way to solve this, then this could spell the end of flammable lithium-ion. Now scientists at Max Plank Institute for Polymer Research have observed dendrite formation at crystal grain boundaries. This discovery may provide a way through the impasse.
Crystal Grain Boundaries and Dendrite Formations
The tendency for dendrites to grow between positive and negative terminals in solid state lithium batteries causes short circuits. Until now, there has been no clear explanation of what causes these branched, tree like structures to develop. The researchers at Max Plank Institute used a special microscopic method to observe this happening.
They found the atoms making up the solid ceramic state electrolyte, arranged themselves in a regular manner as other salts and minerals do. They formed many small crystals that were slightly offset, with grain boundaries separating them akin to our image.
“When the solid state battery is charged,” they explain, “kelvin probe force microscopy reveals how the electrons accumulate along these grain boundaries.” Intriguingly, this mainly occurs along the grain boundaries near the negative pole. What does this tell us concerning dendrite formation at these crystal grain boundaries?
The Dendrites Sprouted at the Electron Accumulations!
Then the Max Plank Institute researchers noticed something unusual. First, the accumulated electrons reduced the transfer of the lithium ions, causing some of the metal to settle. And then this accumulation increased with each recharge, building the dendrites step by step.
At this point in their report, the researchers indulge themselves in speculation. We attach a link to their document below, and leave it for you to ponder over. Although we do hope their speculation proves right, and much good comes from their study of dendrite formation at crystal grain boundaries.
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