A salty battery bath to combat EV range anxiety
The degradation of electrodes in lithium-based batteries has been a major inhibitor to their operating life, particularly when dendrites "growing" from these corroding electrodes short-circuit in the electrolyte. Australian researchers have found that pre-treating lithium electrodes in a special salt bath decreases the breakdown of the electrodes and boosts performance and battery life so markedly it could bring an end to range anxiety for drivers of electric vehicles.
Scientists from the CSIRO, working jointly with researchers from RMIT University and the Queensland University of Technology (QUT), claim that their pre-treating technique is so efficient that even after 1,000 charge/discharge cycles, their prototype retains greater than 99.5 percent Coulombic efficiency, which is a measure of the difference between the incoming and outgoing charges in a battery as it cycles through charging.
The researchers believe that their new process will help bring on the development of super-efficient energy storage methods that will completely negate battery range anxiety that is a major impediment for the electric car industry today.
"Our research has shown by pre-treating lithium metal electrodes, we can create batteries with charge efficiency that greatly exceeds standard lithium batteries," said CSIRO battery researcher Dr Adam Best. "The pre-treatment reduces the breakdown of electrolytes during operation, which is what determines the battery's increased performance and lifetime."
By immersing lithium metal electrodes in an electrolyte bath containing a mixture of the lithium salts Lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6) and the ionic liquid 1-Methyl-1-propylpyrrolidinium chloride (C3mpyr), the pre-treatment covers the surface of the electrode with a protective film that is so efficient that even after more than 2,500 hours of battery cycling, no evidence of any dendrite formation was found.
Whilst a myriad other methods have been researched on eliminating dendrite formation from the degradation of lithium battery electrodes, including coating them with carbon nanospheres and changing the composition of the electrolyte in which they are immersed, this latest technology has shown the largest number of charge/discharge cyclic efficiency with absolutely no dendrite formation visible.
Other advantages of this process include the ability for treated batteries to sit on the shelf for up to a year without their performance being affected, and that the techniques are simple and easy to adopt in current battery manufacturing methods.
The CSIRO holds patents to the electrolyte salt solutions, which come in a variety of different chemical compositions. The research team is now intent on creating and evolving batteries based on the new process and techniques, and is currently searching for commercial collaborators to assist in commercial development of the technology.
The results of this research were recently published in the journal Nature Communications.