Next-generation lithium batteries that offer lightweight, long-lasting, and low-cost energy storage have not been successfully commercialised due to the fact that while rechargeable lithium metal anodes play a key role in how well lithium batteries function, during battery operation they are highly susceptible to the growth of dendrites, microstructures that can lead to dangerous short-circuiting, catching on fire, and even exploding.
Researchers at Columbia Engineering have announced that they have found that alkali metal additives, such as potassium ions, can prevent lithium microstructure proliferation during battery use.
The research team used a combination of microscopy, nuclear magnetic resonance (similar to an MRI), and computational modelling to discover that adding small amounts of potassium salt to a conventional lithium battery electrolyte produced a unique chemistry at the lithium/electrolyte interface.
"Specifically, 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," said PI Lauren Marbella, assistant professor of chemical engineering.
The discovery that alkali metal additives suppress the growth of non-conductive compounds on the surface of lithium metal differs from traditional electrolyte manipulation approaches, which have focused on depositing conductive polymers on the metal's surface.
The work is one of the first in-depth characterizations of the surface chemistry of lithium metal using NMR, and demonstrates the power of this technique to design new electrolytes for lithium metal.
"Commercial electrolytes are a cocktail of carefully selected molecules," 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 optimize electrolyte design and enable stable lithium metal batteries."
The team is currently 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.