Researchers from Columbia University’s engineering department in the US have reported that alkali metal additives, such as potassium ions, can prevent dendritic growth in lithium-ion batteries.
The team found small amounts of potassium salt added to a conventional lithium battery electrolyte produced unique chemistry at the lithium/electrolyte interface.
The team discovered the additives prevented lithium microstructure proliferation during battery cycling by using a combination of microscopy, nuclear magnetic resonance (NMR), and computational modelling.
The methods helped them better understand the reactivity and structure of molecules on the surface of lithium metal anodes.
The study is being published in the journal Cell Reports Physical Science.
Lauren Marbella, assistant professor of chemical engineering, said: “We found that potassium ions mitigate the formation of undesirable chemical compounds that deposit on the surface of lithium metal and prevent lithium ion transport during battery charging and discharging, ultimately limiting microstructural growth.”
Marbella’s results were complemented with density functional theory (DFT) calculations performed by collaborators in the Viswanathan group in mechanical engineering at Carnegie Mellon University.
The work is one of the first in-depth characterizations of the surface chemistry of lithium metal using NMR.
Marbella said: “Using NMR and computer simulations, we can finally understand how these unique electrolyte formulations improve lithium metal battery performance at the molecular level. This insight ultimately gives researchers the tools they need to optimise electrolyte design and enable stable lithium metal batteries.”
The team is now testing alkali metal additives that stop the formation of deleterious surface layers in combination with more traditional additives that encourage the growth of conductive layers on lithium metal. They are also actively using NMR to directly measure the rate of lithium transport through this layer.
