Replacing gadgets like smartphones and laptops just because the battery is no longer charging can be a very tedious task. But new research outlines a way to significantly extend the lifespan of common lithium-ion batteries, starting with the first charge cycle.
Charging the lithium-ion batteries that power most personal electronics and electric vehicles (EVs) at higher temperatures or currents before they hit store shelves could extend their average lifespan by 50%, researchers say. announced in a new study published Aug. 29 in the same journal. Joule.
The findings “point to a generalizable approach to understanding and optimizing this critical step in battery manufacturing,” said study co-author Stephen Torrisi, a senior research scientist at the Toyota Research Institute in California. said in a statement.
A typical lithium-ion battery has a positive electrode and a negative electrode in an electrolyte containing lithium ions. When you charge a battery, lithium ions move to the negative electrode. Then, as you use the battery to drain its charge, the lithium ions move from the negative electrode to the positive electrode. The back-and-forth flow of ions drives the electrical current that powers the device.
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A new lithium-ion battery is fully discharged. The positive electrode is filled with lithium, and the negative electrode has enough space for lithium ions to flow into it. However, during the first charge, some of the lithium in the battery sticks to the surface of the negative electrode. The trapped lithium, along with other components of the electrolyte, becomes part of a layer called the solid electrolyte interface (SEI). This SEI wraps around the negative electrode, protecting it from side reactions that cause further loss of lithium and shorten the battery’s lifespan.
Typically, manufacturers first charge the battery slowly to build up a stable SEI. However, it is not always the most cost-effective approach. Also, recent studies have shown that fast battery charging does not necessarily have a negative effect on battery life. Moreover, several other parameters can affect SEI, so optimizing the first charge for the best battery performance is not trivial.
In the new study, researchers used machine learning to identify the parameters that have the strongest impact on SEI. Two factors caught their attention: current and temperature during the first charge.
By charging the battery in about 20 minutes instead of the usual 10 hours, the overall lifespan of the battery was increased by about 50%. More lithium remains in the SEI on the first charge, which limits the potential for future side reactions that can shorten battery life on subsequent cycles.
Increasing the temperature from room temperature to 131 degrees Fahrenheit (55 degrees Celsius) had a similar effect, increasing battery life by an average of 57%. The researchers said this improvement was likely due to changing the configuration of the SEI to make it more robust. However, these techniques did not have a synergistic effect. Rapidly charging the cells or charging them at higher temperatures did not improve battery performance.
“We didn’t just want to identify the best recipe for making a good battery, we wanted to understand how it was done and “We wanted to understand why it worked.” “This understanding is critical to finding the optimal balance between battery performance and manufacturing efficiency.”
The new strategy could also make batteries cheaper, Chueh said. “This is a great example of how[Stanford Linear Accelerator Center]is doing manufacturing science to make critical technologies for the energy transition more affordable,” he said. “We are solving real challenges facing the industry.”
