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.