Electric vehicles (EVs) and green-energy sources rely heavily on batteries to store electricity. Currently, more than 75 percent of the world’s energy storage depends on batteries that contain lithium, an expensive mineral that’s subject to volatile pricing. Lithium-ion (Li-ion) batteries themselves can be volatile, too, because they use a flammable electrolyte that can catch fire when overcharged.
Now, a group of scientists based in Beijing believes that aluminum offers a better solution. Aluminum is the third-most abundant mineral in the Earth’s crust and costs about one-quarter as much as lithium. And if built right, aluminum-based batteries may offer longer life expectancy and a safer, more sustainable design than their volatile counterparts. Led by scientists from the Beijing Institute of Technology and the University of Science and Technology Beijing, the group has found a way to stabilize aluminum batteries that can last far longer.
Aluminum-ion (Al-ion) batteries have been the subject of research for years. But previous attempts have generally used ionic liquid electrolytes, which can lead to anode corrosion, especially in humid conditions. Other researchers have used gel-polymer electrolytes, halfway between liquid and solid-state alternatives, but these tend to have low conductivity. This team of researchers took a different approach and added a pinch of salt—namely, an inert aluminum fluoride salt—to a liquid electrolyte containing aluminum ions, creating a solid-state electrolyte.
Well, more than a pinch of salt, really. The salt has a porous 3D structure, which allows it to act like a rigid sponge that absorbs and stabilizes the liquid yet still allows the ions to move more freely. This increases conductivity of the material, and the result is a solid composite material that cannot leak. The researchers also coated the electrodes with a thin layer of material that helps prevent crystals of aluminum from forming, which would degrade battery performance over time.
“Our research shows that a stable, recyclable solid-state electrolyte can improve aluminum-ion batteries by solving issues like corrosion, safety, and long-cycle life, making them a potential alternative to lithium-based batteries,” says Shuqiang Jiao, a professor of electrochemical engineering at the University of Science and Technology Beijing.
Aluminum’s Advantages
The researcher’s tests demonstrated that the resulting battery design can have an extremely long life, with the battery retaining 99 percent of its original capacity after 10,000 charge/discharge cycles. In contrast, a typical Li-ion battery retains only 80 percent of its charge capacity after 300 to 500 cycles, depending on the conditions.
The solid-state electrolyte is also safer than typical Li-ion designs, which use liquid electrolytes. It won’t leak the way conventional batteries with a liquid electrolyte can, so the researcher’s Al-ion batteries continued to function normally when damaged by repeated punctures, even when penetrated all the way through. The batteries were also tested at temperatures as high as 200 °C; the output voltage was nearly the same in spite of the heat, and the battery didn’t expand or deform excessively.
In addition to these performance advantages, the Al-ion battery boasts better recyclability, compared to conventional Li-ion designs. The researchers found that they were able to easily recover as much as 80 percent of the aluminum fluoride salt from the lab experiments, and they predict much higher levels of recovery at industrial scales. The solid aluminum foil can also be reused after a simple surface cleaning. As a result, the entire design lends itself to efficient recycling of the components.
A better battery could have a major impact on many markets. “Innovations that elongate battery life and bring down costs have the potential to transform multiple industries, from automotive to consumer electronics and home security,” says Jennifer Kent, vice president of research at market research firm Parks Associates. “Battery range is a top barrier for EV purchases, for instance, with 39 percent of those not owning or intending to buy an EV saying that EVs need to be charged too frequently or have a limited driving range.” Less expensive batteries could also play an important role in advancing the use of sustainable energy sources, such as wind and solar, by providing a cost-effective way to store excess energy until it is needed.
The new battery structure should be easy to manufacture at commercial scale. But before the Al-ion battery is ready for commercial applications, its energy density will need to be improved, the researchers say. Still, this new approach offers the potential for batteries that are safer, less expensive, longer lasting, and easier to recycle efficiently.
This story was updated on 5 February 2025 to include a quote from Shuqjiang Jiao.
This article appears in the April 2025 print issue as “For Stable Aluminum Batteries, Just Add Salt.”
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Alfred Poor is a technology speaker and writer with a focus on health tech. He was the editor of “Health Tech Insider,” a website that covered wearable and mobile devices for health and medical applications. He also helps tech company executives make a better impression in video meetings and online presentations. A graduate of Harvard College, he is the author or co-author of 15 books and is widely quoted in major media outlets.
