In lithium-ion batteries, a separator is placed in the electrolyte. What is more, if the dendrites grow through the electrolyte solution and make contact with the other electrode, then the battery may experience a catastrophic event – in other words, an explosion or fire. However, over the course of many charge-discharge cycles, lithium builds up unevenly on the battery's lithium metal electrode in a branching or 'dendritic' pattern and ultimately causes the battery to go dead. Lithium-metal batteries are so useful because of their high-energy density and relatively light weight compared with conventional batteries. 'Our findings demonstrate that two-dimensional materials – in this case, graphene oxide – can help regulate lithium deposition in such a way that extends the life of lithium-metal batteries,' said Reza Shahbazian-Yassar, associate professor of mechanical and industrial engineering in the UIC College of Engineering and corresponding author of the paper. The researchers report their findings in a paper in Advanced Functional Materials. Their solution is a graphene oxide-coated 'nanosheet' that, when placed in between the two electrodes of a lithium-metal battery, prevents uneven plating of lithium and allows the battery to safely function for hundreds of charge/discharge cycles. Now, researchers at the University of Illinois at Chicago (UIC) have developed a solution to this problem. This build-up cuts the lives of these batteries too short to make them viable and, more importantly, can cause the batteries to short-circuit and catch fire. Lithium-metal batteries – which can hold up to 10 times more charge than the lithium-ion batteries that currently power our phones, laptops and cars – haven't been commercialized yet because of a fatal flaw: as these batteries charge and discharge, lithium is deposited unevenly on the electrodes. Right: Lithium plates uniformly on a lithium electrode in a battery with a graphene oxide nanosheet separator. Left: Dendrites forming on a lithium electrode.

Dendrite growth