Lithium metal batteries hold tremendous promise for next-generation energy storage because the lithium metal negative electrode has 10 times more theoretical specific capacity than the graphite electrode used in commercial Li-ion batteries. However, lithium is one of the most difficult materials to manipulate, due to its internal dendrite growth mechanism, which can cause Li-ion batteries to short circuit, catch fire or even explode.
The growth of these needle-like lithium whiskers that form internally in battery electrodes is known to be affected by how ions move in the electrolyte, but researchers do not understand how ion transport and inhomogeneous ionic concentration affect the morphology of lithium deposition.
Columbia University researchers used stimulated Raman scattering microscopy to explore the mechanism behind dendrite growth, becoming the first team of material scientists to directly observe ion transport in electrolytes. A lithium deposition process was observed that corresponds to three stages: no depletion, a partial depletion and full depletion of lithium ions. A feedback mechanism was also uncovered between lithium dendrite growth and heterogeneity of local ionic concentration that can be suppressed by artificial solid electrolyte interphase in the second and third stages.
The researchers have developed a method to inhibit dendrite growth by homogenizing the ionic concentration on the lithium surface at the second and third stages of the lithium deposition process.
The research is published in Nature Communications.