A team at the University of Waterloo have solved two of the biggest issues regarding lithium-oxygen batteries. Thanks to a new breakthrough, we could be a step closer towards rechargeable lithium-oxygen batteries. (Photo via James Walker/Digital Journal)
Lithium-oxygen batteries are seen as the ultimate rechargeable battery largely due to their theoretical-energy density, but issues with their chemistry and stability have prevented this concept from becoming a reality. Now, we may be a step closer thanks to a new breakthrough from the University of Waterloo’s chemists.
These chemists have successfully solved two of the biggest issues regarding lithium-oxygen batteries and created a working battery with near 100 percent coulombic efficiency in the process. With their new study, the team proved that four-electron conversion for lithium-oxygen electrochemistry is highly reversible. This makes them the first to successfully achieve four-electron conversion, which increases the electron storage of lithium-oxygen batteries.
The intermediate of the cell chemistry and the peroxide product reacting with the porous carbon cathode is one of the lithium-oxygen batteries’ biggest issues – it degrades the cell from within. To make things worse, the superoxide eats the organic electrolyte and limits its life cycle. To offset this, the team used a more stable inorganic molten salt and a bifunctional metal oxide catalyst. The battery was then operated at 150 C, which resulted in a more stable product superoxide being formed instead of the peroxide product. This results is a highly reversible Li-oxygen battery with coulombic efficiency approaching 100 percent.
Because the battery store oxygen as lithium oxide instead of lithium peroxide, it was able to main excellent charging characteristics and achieved the maximum four-electron transfer in the system increasing the theoretical energy storage by fifty percent.
“By swapping out the electrolyte and the electrode host and raising the temperature, we show the system performs remarkably well,” said Linda Nazar, member of the Waterloo Institute for Nanotechnology and senior author on the project.
This is a huge development for rechargeable lithium-oxygen batteries, but there’s still a lot of work that needs to be done. Luckily, this breakthrough means that these batteries can be more than just a curiosity. Hopefully, it won’t be too long until these batteries become a reality.
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