An international team of scientists has developed a method of boosting the lifetime of lithium metal batteries to “hundreds” of cycles by preventing dendritic growth.
The researchers used a separator made of an extremely thin, two-dimensional membrane made of carbon to reach more than 300 cycles of their battery.
At less than one nanometer, the separator pores are smaller than the critical nucleus size and, as such, prevent the nucleation that leads to the formation of dendrites.
Instead of forming dendritic structures, the lithium is deposited on the anode as a smooth film, which prevents the separator membrane being damaged and affecting the functionality of the battery.
The team included scientists from Friedrich Schiller University Jena in Germany, and Boston University (BU) and Wayne State University (WSU) in the US.
The researchers report on their method in the journal Advanced Energy Materials.
Dr Antony George from the University of Jena, said: “To test our method, we recharged test batteries fitted with our Hybrid Separator Membrane over and over again.
“Even after hundreds of charging and discharging cycles, we couldn’t detect any dendritic growth.”
Associate professor Leela Mohana Reddy Arava from the WSU, said the key innovation was stabilising electrode/electrolyte interface with an ultra-thin membrane that did not alter current battery manufacturing process.
Sathish Rajendran, a graduate student at WSU, said: “The separator gets the least amount of attention when compared to the other components of the battery.
“The extent to which a nanometer thick two-dimensional membrane on the separator could make a difference in the lifetime of a battery is fascinating.”
As a result, the research team is confident their findings have the potential to bring about a new generation of lithium batteries.
They have applied for a patent for their method.
The next step is to see how the application of the two-dimensional membrane can be integrated into the manufacturing process.
The researchers also want to apply the idea to other types of batteries.
Image (Turchanin et al./Wiley): a) Regular battery separators with microscale porosity cause non-uniform lithium transport during the battery charge-discharge cycles resulting in needle-like growth of metallic lithium. This leads to short circuits and premature failure of lithium metal batteries. b) By introducing a carbon nanomembrane on the regular battery separator, the growth of lithium needles can be suppressed. The sub-nanometer-sized pores in carbon nanomembranes regulate the transport of lithium ions during the battery charge-discharge cycles, resulting in the deposition of a smooth film and the battery life can be increased significantly.