Why we can’t charge lithium-ion EV batteries in a few minutes
Graphite is a troublemaker
Story byIoanna Lykiardopoulou
Ioanna is a writer at TNW. She covers the full spectrum of the European tech ecosystem, with a particular interest in startups, sustainabili(show all)Ioanna is a writer at TNW. She covers the full spectrum of the European tech ecosystem, with a particular interest in startups, sustainability, green tech, AI, and EU policy. With a background in the humanities, she has a soft spot for social impact-enabling technologies.
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Breaking down the findings
The anode of lithium-ion EV batteries is typically made of graphite in the form of short particles.
Lithium ions can insert themselves into these particles through a process known as “intercalation.”When intercalation takes place properly, the battery can successfully charge and discharge. But that’s where we hit the snag that’s taming our wildest charging fantasies.
When a battery is charged fast, the intercalation process can get a bit rocky — which, as we now know, isn’t great for the battery. So let’s take a look at what exactly is happening.
1. The graphite particles become distorted
The scientific team discovered that repeated fast charging made thegraphite atoms at the particle edges distorted, hindering the intercalation process.
2. Lithium ions can’t enter the graphite particles
As a result, lithium ions can find their “way home” inside the graphite, so they tend to aggregate on top of the anode’s surface, creating a “plating” effect — simply put, they form a thick deposit on the anode’s top.
3. The anode expands
The lithium ions’ plating makes the anode undergo some degree of irreversible expansion, which in turn impairs battery performance.
Conclusions
Daniel Abraham, battery scientist and co-author of the study explains:
So… what’s the takeaway?
Super-fast charging with graphite-based lithium EV batteries doesn’t seem very likely at the moment. I’m sorry.
So for super-fast charging to become a reality, we need to hope for a breakthrough in graphite technology. That would be optimal as most EVs today run on graphite-based lithium.
However, the good news is that we aren’t bound to them, as we’re eyeing the possibilities of alternatives such assiliconandsemiconductor nanoparticlesmaybe becoming commercial. But whatever the super-fast charging solution will be, it doesn’t seem like it’ll be here super-fast.
You can find the research-based paper, published in the Journal of The Electrochemical Society,here.
