These Water Batteries Outlast Lithium And Could Eliminate Fire Risks For Good

We've gotten pretty good at making batteries that hold a lot of power. Unfortunately, we've been less good at making ones that don't eventually corrode, catch fire, or poison the ground they end up in. A new advancement attempts to change that: a new kind of battery that runs on water and tofu brine. Better yet, it lasts 120,000 charge cycles in the lab. That's roughly 40 times higher than your typical lithium-ion batteries, which max out at around 3,000 cycles before degrading. Theoretically, if you charge one of these once a day, you could keep them running for over 300 years. Obviously, nobody's phone or even EV is lasting that long, but the promise is real.

So how does this actually work? The electrolyte — that's the liquid inside a battery responsible for moving electric charge between the two electrodes — is made from neutral salts of magnesium and calcium. Those happen to be the same minerals found in tofu brine, the stuff used to curdle soy milk during tofu production. The researchers also kept the solution at a neutral pH of 7.0, which helped avoid the corrosive side reactions that destroy conventional batteries from the inside.

That said, the liquid was only one piece of the puzzle. The researchers also swapped out the typical metal-based negative electrode in their battery for one made from organic polymers, which are essentially plastics. For the positive electrode, they went with an analog of the paint pigment Prussian blue. Ultimately, as shown in the full study in Nature Communications, they landed on an impressive energy capacity of 112.8 milliamp hours per gram, which is impressive for this type of battery.

There's a reason researchers are looking at water-based alternatives. Lithium-ion batteries power basically everything right now, but they come with a problem. The flammable solvents used as electrolytes can catch fire if the batteries overheat or get damaged. That's led to incidents on airplanes where portable batteries ignited mid-flight, and some airlines have already started banning power banks on flights. A rise in EV fires — which are notoriously hard to put out – has also reignited debates about whether lithium-ion is really safe enough for the long haul.

Water-based batteries sidestep all of that entirely. There's no fire risk because the electrolyte is non-flammable. There's also no need for hazardous waste processing when you throw them away. The researchers confirmed that the batteries meet international disposal standards, including the U.S. Resource Conservation and Recovery Act.

These aqueous batteries are also generally cheaper to produce. They rely on ingredients that cost far less than what goes into a standard lithium-ion cell, making them especially appealing for large-scale grid storage – think solar farms and wind energy balancing — where you need something durable and affordable rather than compact and energy-dense. That said, there are still hurdles. The energy density needs to go up before these could compete in applications where size and weight matter. Scaling up production of those organic polymers is another challenge the team openly acknowledges. But if they can figure those out, this could become a real contender for stationary energy storage down the line. And it's just one of several new battery technologies in the pipeline that could eventually change everything from EVs to smartphones.