Lithium-ion batteries pack a lot of energy into tight spaces. They charge smartphones, laptops, game controllers and electric toothbrushes. The problem is that lithium-ion batteries can be dangerous. If a cell is overheated or damaged, it can lead to thermal runaway, which is a chain reaction that can cause a fire, explosion, or even release toxic gases. Despite attempts to extend the life of lithium-ion batteries, their disposal can be problematic. Aqueous batteries are a safer alternative because they are built around non-flammable water-based electrolytes. However, they present their own problems, including corrosion and unwanted chemical reactions that can shorten their lifespan. Now, Chinese researchers may have solved these problems by creating a long-lasting battery that relies on the same chemistry used to make tofu.
Many aqueous batteries use acidic or alkaline electrolytes which can produce unwanted electrochemical reactions, such as consuming water and damaging electrode materials. These reactions shorten battery life and the electrolytes can make their removal difficult. The researchers claim to have solved this problem by combining a specially designed organic polymer with a neutral electrolyte to reduce unwanted side reactions. Instead of using acidic or alkaline electrolytes, they used a neutral mixture of water and magnesium or calcium salts. Interestingly, the same mineral salts can be used to coagulate soy milk into tofu.
The scientists charged and discharged the experimental battery 120,000 times without failure. One complete charge-discharge cycle per day is equivalent to approximately 329 years of cycling. They tested separate versions using magnesium chloride and calcium chloride. In the magnesium chloride test, the battery retained approximately 72% of its capacity.
China’s water battery could transform energy storage
Aqueous batteries, like the magnesium and calcium-based cells studied, have the potential to provide safe, cheap and sustainable energy storage. Think of a house with solar panels that send electricity to a battery that you wouldn’t mind connecting to your house. This idea holds on a larger scale, which is why a 2024 paper published in Chemical Society Reviews suggests that aqueous batteries are well suited for grid-scale energy storage, particularly renewable energy. Solar and wind are variable sources that require a way to store energy during periods without sun or wind.
Frequent cycling is where this technology becomes interesting. Forget 329 years, the result of 120,000 cycles could have practical value over your lifetime. At home, solar batteries can charge during the day and discharge later. If battery durability translates to a home’s electrical system, it could keep the same home running for generations. Then there are the gadgets you’re constantly loading and unloading. The current cycle degrades lithium-ion batteries. A battery with that kind of lifespan could, in theory, prevent you from replacing a Steam Deck that you’ve spent years customizing with Decky Loader plugins, themes, and other modifications.
When it’s time to dispose of your aqueous battery, recycling is an option, as it is loaded with recoverable electrode and electrolyte materials. Of course, after powering your iPod Shuffle for 300 years, researchers say you could simply toss the battery in the trash with few ecological consequences.
