How water could make safer batteries

There’s also growing concern about fires started by e-bikes in New York City. These fires, which can be deadly, have mostly been caused by bikes that aren’t repaired correctly or use substandard batteries, highlighting the need for regulation and tight quality control of batteries. 

What it comes down to is this: lithium-ion batteries can catch fire. It doesn’t happen often, and there are many, many safety controls that can be put in place to manage the risk effectively. But some battery makers want to build alternatives that can’t catch fire in the first place. 

Watering it down

Lithium-ion chemistry has been optimized over decades to pack a lot of energy into a small, lightweight device and deliver a lot of power. 

Part of that optimization is in the liquid electrolyte: standard lithium-based batteries use organic solvents mixed with salts to shuttle charge around. Theoretically, batteries can use water as the solvent, but they usually don’t. That’s for a pretty good reason: the high voltage common in lithium-ion batteries, which is needed to deliver high power, can pull water apart into hydrogen and oxygen. 

But when it comes to huge storage installations on the grid, there’s a different balance to strike. Rather than focusing on packing lots of energy into a small battery, researchers and companies want above all to lower the batteries’ cost.  

So batteries destined for storage on the grid can make some compromises. They might not need to charge and discharge so quickly, and it’s less crucial to get them as small and light as possible. 

That opens up the possibility of using heavier materials, like iron and zinc. And with lower power and lower voltages needed, companies can use water with salts mixed in as an electrolyte. That could help save on costs, make the batteries easier to manufacture, and also help with safety. You’d probably have a hard time setting water-based batteries on fire, even if you tried. 

Some companies are leaning into the benefits of using water in their alternative batteries as they start to make progress toward commercialization.