New seawater battery could replace expensive lithium batteries

Open your smartphone and you’ll probably find a lithium-ion battery inside. They’re rechargeable, which is great – but they’re difficult to dispose of, and the price of lithium is soaring. Nine scientists from Ulsan National Institute of Science and Technology (UNIST) in South Korea developed a groundbreaking alternative: a new battery made from abundant and readily available seawater.

Lithium-ion batteries – found in devices like iPhones and Tesla’s Powerwall – can help us end our fossil fuel dependence. But concerns over how lithium is mined and rising expenses mean we haven’t created the perfect battery yet. UNIST researchers turned to seawater for a superior solution.

Their device is technically a sodium-air, or sodium oxygen, battery. While sodium-air batteries are more cost-effective than lithium-ion batteries, they’re not quite ready for commercial distribution. Part of the goal of the researchers’ work was to address some of the challenges that stand in the way of commercialization – and they may have found an answer in seawater.

It turns out seawater serves as an excellent catholyte – a cathode and electrolyte combined together. In a paper published in the ACS journal Applied Materials & Interfaces, the researchers state: “A constant flow of seawater into and out of the battery provides the sodium ions and water responsible for producing a charge.”

Their seawater battery can be compared against lithium-ion batteries by measuring discharge voltage. The seawater battery had an average discharge voltage of around 2.7 volts, according to ACS, while the same statistic for a lithium ion battery is 3.6 to four volts. That means the scientists still have work to do, but their device might just bring us closer to a world where we don’t need to depend on lithium for energy storage.