Seawater for batteries?


SKorean study shows sodium-oxygen could replace lithium-ion used in rechargeable batteries

A breakthrough in battery technology using seawater could soon replace lithium as a material in rechargeable batteries used in smartphones and other gadgets, researchers in South Korea revealed in a new study published in the journal ACS Applied Materials & Interfaces.

Sodium-oxygen batteries are considered a promising and cost-effective alternative to common lithium-ion batteries, which are handicapped by rising costs of the lithium material, and environmental and safety concerns about lithium mining.

Most lithium ore is mined and processed in China and the United States, with smaller amounts produced by Australia, Canada, and Russia.

Researchers from the Ulsan National Institute of Science and Technology in South Korea used seawater as a catholyte, a combination of an electrolyte and cathode. In batteries, the electrolyte is the component that allows an electrical charge to flow between the cathode and anode. In the battery developed by the research team, a constant flow of seawater into and out of the battery provides the sodium ions and water responsible for producing a charge.

The technology behind seawater batteries has been known for some time, but the material is comparatively inefficient. To improve the speed of the reactions, the researchers explained, the team prepared a catalyst using porous cobalt manganese oxide nanoparticles. The pores create a large surface area for encouraging the electrochemical reactions needed to produce a charge. A hard carbon electrode served as the anode.

According to the study, the resulting battery performed efficiently over 100 cycles with an average discharge voltage of about 2.7 volts, compared to a lithium-ion cell, which has an average discharge voltage of 3.6 to 4.0 volts. “This advance is getting close to bridging the gap,” between seawater and lithium batteries, the researchers said, making commercial viability of the new battery possible within a few years.


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