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Scientists developing sustainable seawater batteries


Korean university UNIST will be working with public organisations in the energy sector to develop a new type of eco-friendly battery that can store and produce electricity using seawater. The project is expected to accelerate the commercialisation of eco-friendly, cost-efficient, and high-stability seawater batteries.

The project’s consortium includes Korea Electric Power Corporation (KEPCO), Korea East-West Power Company Ltd. (EWP), and the Ulsan National Institute of Science and Technology (UNIST).

Seawater batteries use sodium, the sixth-most abundant element on earth, to generate electricity. This makes this system an attractive supplement to existing battery technologies. Furthermore, this new type of battery is much cheaper and more environmentally friendly than lithium and will, therefore, offer a low-cost route to large-scale energy storage. Moreover, the use of seawater can also considerably reduce fire risks, as it keeps the thermal fluid in good condition.

Seawater batteries operate without auxiliary loads or an external power supply, except for water and salt. Therefore, they can be applied as energy storage systems (ESS) for homes and industries or as emergency power supplies for large ships and nuclear power plants.

Seawater batteries are similar to their lithium-ion cousins since they store energy in the same way. The battery extracts sodium ions from the seawater when it is charged with electrical energy and stores them within the cathode compartment. Upon electrochemical discharge, sodium is released from the anode and reacts with water and oxygen from the seawater cathode to form sodium hydroxide. This process provides energy to power, for instance, an electric vehicle.

While seawater batteries are more cost-effective than lithium-ion batteries, they are not quite ready for commercial distribution. Part of the reason is that these batteries have relatively low electrical power output. To overcome this, UNIST will help design a more optimised cell geometry and standardised procedures for the battery. Together with KEPCO, the research team at UNIST plans on building cells with various sizes and shapes, thereby enhancing the charge rate of the battery by 20Wh. Generally, a small smartphone lithium-ion battery stores about 10Wh.

With the support of KEPCO, UNIST will establish a testing facility to mass produce seawater batteries, as well as to develop a seawater battery pack that enhances the charge rate of the battery by connecting cells. By 2018, the joint research team will build a 10Wh seawater battery pack at Ulsan Thermal Power Plant. 10Wh is the average amount of energy required per day for a family of four.

“Once this battery is commercialised, we can lead the 47 trillion won worth, advanced energy storage devices market,” said Professor Youngsik Kim of Energy and Chemical Engineering at UNIST.

“It will become one of the major growth engines in the future of our economy, contributing to the revitalisation of the new energy industry.”

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