Air-breathing sulfur battery, the new cheapest energy-storage system

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sulfur battery

Air-breathing sulfur battery

Wind and solar power are popular sources for renewable energy. Now, MIT researchers developed an “air-breathing” battery that stores electricity long-term for about a one-fifth the cost of current technologies. The battery could use to make sporadic renewable power, a reliable source of electricity for the grid.

For its anode, the rechargeable flow battery uses cheap, abundant sulfur dissolved in water. Liquid salt solution in the cathode continuously takes in and releases oxygen that balance charge as ions shuttle between the electrodes. Oxygen flowing into the cathode causes the anode to discharge electrons to an external circuit. Oxygen flowing out sends electrons back to the anode, recharging the battery.

This battery literally inhales and exhales air, but it doesn’t exhale carbon dioxide, like humans, says, Yet-Ming Chiang, co-author of the study.

Researchers said, the batterie’s total chemical cost is about 1/30th the cost of lithium-ion batteries. They estimate a scaled-up version of their flow battery would cost between US$20 and $30 per kWh stored to run.

The new battery technologies have relied on more expensive raw materials than the previous. This reflects a trend for researchers to prioritize energy density over cost.

Anolyte made up of sulfur

In this case, the anolyte made up of sulfur dissolved in water, and the hunt for an equally abundant material for the catholyte to an oxygenated liquid salt solution.

The clever part of the battery is the fact that the catholyte “breathes” air from outside while discharging, and exhales while recharging. By this mechanism, the battery creates negatively-charged hydroxide ions in the catholyte while inhaling. While recharging that oxygen released, creating hydrogen ions which then send electrons back into the anolyte.

Lithium-air batteries use the same mechanism, but sulfur, water and salt far cheaper materials, and cost-cutting is key to scaling up energy storage systems for use with the grid. The new battery would cost far less to make and run than lithium-ion batteries.

The current prototype is about the size of a coffee cup, but the design can be scaled up for use in larger applications. The team plans to make the battery more efficient, less expensive.

More Information: [Joule]

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