Electric vehicle batteries could one day charge faster without wearing out as quickly, thanks to a new approach that uses a detailed virtual copy of the battery’s internal structure.
Researchers at the Korea Advanced Institute of Science and Technology (KAIST) created a three-dimensional “digital twin” of a commercial lithium-ion battery electrode.
Their study, published in the journal InfoMat, reveals that battery performance depends not only on what materials are inside an electrode, but also on exactly where those materials are located.
Fast charging is one of the biggest challenges facing electric vehicles. Drivers want to recharge in minutes rather than hours, but pushing lithium ions into a battery too quickly can damage it and shorten its useful life.
A lithium-ion battery’s graphite anode contains graphite particles that store lithium, a binder that holds those particles together and tiny pores filled with electrolyte.
During charging, lithium ions travel through the electrolyte and enter the graphite.
When charging happens too quickly, however, some lithium ions can’t enter the graphite fast enough. Instead, they can collect as metallic lithium on the graphite surface, a damaging process called lithium plating.
It is similar to too many cars arriving at a parking lot at once. If they can’t enter quickly enough, traffic begins piling up outside.
Other changes happen at the same time. A protective layer called the solid electrolyte interphase, or SEI, forms on graphite particles. Some SEI is necessary for normal battery operation, but if it becomes too thick or uneven, battery performance can suffer.
Graphite particles also expand as they absorb lithium, creating mechanical stress inside the electrode. Because all these processes happen on extremely small scales, studying exactly where problems develop is difficult.
To get a clearer picture, researchers led by Professor Kang Taek Lee reconstructed a real commercial graphite anode in three dimensions. Their digital model included individual graphite particles, binder material and the pores used by lithium ions.
They then virtually changed factors including electrode thickness, pore space and binder distribution before simulating fast charging.
The results showed that binder placement could make a surprisingly large difference.
In anodes 50 micrometers thick, different binder arrangements produced less than a 4% difference in overall charging capacity. That small difference could make the designs appear almost identical in a conventional performance test.
Inside the electrodes, however, the situation was very different.
When too much binder accumulated near the separator, it reduced the available pathways for lithium ions. This created something like a traffic bottleneck and increased lithium plating near another part of the electrode by more than 10% compared with an electrode where binder was distributed evenly.
A more even binder distribution allowed lithium ions to travel more uniformly and also encouraged a more even protective SEI layer.
The problem became even more important with thicker electrodes. In 83-micrometer anodes, changing the binder distribution resulted in about an 18% difference in charging capacity.
Pore placement mattered too. Areas with enough empty space could better accommodate graphite particles as they expanded, while tightly packed regions experienced greater mechanical stress.
The study suggests that future EV batteries may need to be designed at a much more detailed level. Engineers shouldn’t simply decide how much graphite, binder and pore space an electrode needs—they also need to control where each is located.
Digital twins could allow researchers to test these microscopic arrangements virtually before manufacturing batteries, potentially speeding the search for EV batteries that combine rapid charging, high energy storage and longer lifespans.
