When we think about batteries, especially the kind that powers everything from our phones to electric cars, we usually focus on electrical stuff like how long they last or how quickly they can charge.
However, scientists at the University of Illinois Urbana-Champaign are looking at batteries in a whole new light—or more accurately, a new temperature. They’re exploring how heat and electricity work together inside batteries, which could lead to some exciting improvements.
Batteries work by moving lithium ions from one end to the other. This process is well understood through its electrical aspects, like voltage and current. But the team in Illinois has taken a different approach by focusing on the Peltier effect.
This effect is about how electrical currents can make things heat up or cool down. While it’s a common idea in gadgets that keep your computer cool, it’s not something scientists have looked into much for batteries.
The researchers used this Peltier effect to peek into the chemical heart of lithium-ion batteries. By carefully measuring tiny temperature changes when electricity flows, they’ve managed to measure something called entropy in the battery’s electrolyte.
Entropy is a bit like a fingerprint for molecules, telling us about the lithium ions’ behavior and how they interact with their surroundings in the battery.
Why does this matter? Well, understanding entropy helps scientists figure out how efficiently batteries can work and how they might last longer. The electrolyte is the liquid inside the battery that the lithium ions move through.
By knowing more about its entropy, researchers can think about how to design better electrolytes. Better electrolytes mean better batteries—ones that could charge faster, last longer, or be more reliable.
This method of studying batteries is pretty clever because it looks at both heat and electricity together, which hasn’t been done much before, especially for the liquid part of batteries.
The team managed to measure really small temperature differences, as tiny as one hundred-thousandth of a degree Celsius. These measurements helped them understand how changing different things like the concentration of lithium ions or the type of solvent affects the battery’s chemistry.
What they found was pretty interesting: when lithium ions move around in the battery, it actually cools down a bit, opposite to the direction they’re moving.
This hints at the interactions between lithium ions and the electrolyte being a bit more orderly than the chaotic mix you’d find in solid lithium.
Knowing all this stuff is super important for making batteries better. For instance, when a battery charges and discharges, lithium ions shuffle back and forth, and understanding their entropy could make this process more efficient.
Also, where the electrolyte touches the battery’s electrodes, it starts to break down and form a layer called the solid-electrolyte interphase.
This layer is crucial for the battery’s life, and getting a grip on the thermodynamics here, through entropy measurements, could help make batteries that last much longer after many charges and discharges.
In a nutshell, this research is opening up new ways to think about and design the next generation of lithium-ion batteries, with the promise of making our gadgets and electric vehicles even better in the future.
The research findings can be found in Physical Chemistry Chemical Physics.
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