Scientists Discovered a Way to Make Your Batteries Survive Way Longer

Aug 30, 2024

Illustration of an energy-efficient conveyor belt transporting power batteries past a control unit and a digital screen displaying energy consumption trends with a downward arrow and dollar symbol, suggesting cost savings. The background is purple.

Scientists at the SLAC-Stanford Battery Center in Menlo Park, California, have found a surprising way to improve lithium-ion battery lifespan by 50%.

The novel discovery shows that a lithium-ion battery’s first charge is “more momentous than it sounds.” The nature of the first charge determines a battery’s performance and lifespan (how many times it can be charged and discharged before it deteriorates).

Dying lithium-ion batteries are an all-too-familiar problem for everyone, as nearly all modern electronics rely on lithium-ion batteries, including smartphones, laptops, tablets, and cameras.

Researchers at SLAC-Stanford Battery Center report in a study published today in Joule that giving batteries their first charge “at unusually high currents increased their average lifespan by 50% while decreasing the initial charging time from 10 hours to just 20 minutes.”

The scientists were also able to use scientific machine learning to account for the specific changes in the battery to account for the increase in lifespan and performance, “invaluable insights for battery manufacturers looking to streamline their process and improve their products.”

The study was performed by a team at SLAC/Stanford and led by Professor Will Chueh alongside researchers from the Toyota Research Institute (TRI), the Massachusetts Institute of Technology, and the University of Washington.

“This is an excellent example of how SLAC is doing manufacturing science to make critical technologies for the energy transition more affordable,” Chueh says. “We’re solving a real challenge that industry is facing; critically, we partner with industry from the get-go.”

“This study is very exciting for us,” TRI senior researcher Steven Torrisi adds. “Battery manufacturing is extremely capital, energy and time intensive. It takes a long time to spin up manufacturing of a new battery, and it’s really difficult to optimize the manufacturing process because there are so many factors involved.”

Although the comprehensive details of the research are included in the complete study, newly published in Joule, the gist is that the positive electrode of a brand-new lithium-ion battery is 100% full of lithium. During the initial charge, which requires that lithium flow into the negative electrode, some of the lithium is deactivated and lost to use forever. This is true every time a lithium-ion battery goes through a charge-discharge cycle, and why the batteries deliver decreased performance over time. Minimizing these losses is a significant focus for battery manufacturers. However, improving battery manufacturing is so capital, energy, and time-intensive that it is exceptionally challenging for companies to optimize battery production.

A diagram showing the evolution of head space in a battery with labeled positive and negative electrodes. It depicts stages: before initial charge, during initial charge (showing SEI layer and side reactions), after discharge, and after subsequent charge. — ‘Factory-charging a new lithium-ion battery with high currents significantly depletes its lithium supply but prolongs the battery’s life, according to research at the SLAC-Stanford Battery Center. The lost lithium is generally usually used to form a protective layer called SEI on the negative electrode. However, under fast charging conditions, lithium ions are also consumed during side reactions at the negative electrode. This creates additional headspace in both electrodes and helps improve battery performance and lifespan.’ | SLAC

Xiao Cui, the lead researcher in Chueh’s lab, says that, oddly enough, one way to minimize the lithium loss is to deliberately lose a large percentage of the initial lithium supply during the battery’s first charge during production.

The lost lithium becomes part of a “squishy layer” called the solid electrolyte interphase (SEI). This forms on the surface of the negative electrode during the initial charge. “The SEI then protects the negative electrode from side reactions that would accelerate the lithium loss and degrade the battery faster over time,” SLAC explains. “Getting the SEI just right is so important that the first charge is known as the formation charge.”

Formation is a vital step for battery manufacturing. Historically, this was performed using very low current over an extended period — 10 hours or so. The theory has long been that charging at low currents creates “the most robust SEI layer.”

However, not only is this formation process slow and costly, it seems it’s also not the best way to improve the longevity and performance of lithium-ion batteries.

“Experiments confirmed that charging at high currents has a huge impact, increasing the lifespan of the average test battery by 50%. It also deactivated a much higher percentage of lithium up front — about 30%, compared to 9% with previous methods — but that turned out to have a positive effect,” SLAC explains.

If this research can be translated to real-world lithium-ion battery production, as the researchers believe, it may soon be the case that smartphones offer good battery performance for more than a couple of years, and camera batteries deliver consistent performance for a very long time.

Image credits: SLAC. ‘Data-driven analysis of battery formation reveals the role of electrode utilization in extending cycle life,’ by Cui, Kang, Wang, Bazant, Sun, Chueh, et al.