Seawater: The next sustainable battery revolution

Seawater covers most of the globe and makes up around 97 per cent of all water on Earth. It could also hold the key to cheaper and greener batteries for storing green energy collected from wind turbines and solar cells.

Using the Canadian Light Source (CLS) at the University of Saskatchewan, an international research team involving scientists from Switzerland, Canada, and the United States, has shown that with some minor modifications, chloride – a sustainable and readily available component of seawater – could one day be the material that shuttles ions back and forth between the electrodes in solid-state batteries used for grid-scale energy storage.

Lithium is currently at the heart of modern batteries, powering everything from our smartphones to e-bikes and electric cars. But there’s a very real risk that the material could become scarcer and more expensive in the future. According to Natural Resources Canada, lithium production has more than doubled world-wide in in the past five years. And a handful of countries hold most of the planet’s lithium stores. Canada’s supplies amount to only 4.4 per cent of the total worldwide.

“We're not looking to entirely replace lithium-ion batteries, but we need other solutions in the next few decades if we are going to meet this massive need that the world will have for hundreds of terawatt hours that allow for effective use of solar and wind,” said Sarbajit Banerjee, professor at ETH Zürich, a public university in Switzerland, and Head of the Laboratory for Battery Science at Switzerland’s Paul Scherrer Institute.

That’s why researchers are studying alternatives such as chloride. One of the challenges with using chloride for batteries is that doesn’t do a good job of storing energy. Unlike the ions in lithium, chloride ions have a tough time moving through solid materials. Banerjee uses the analogy of a street with high walls on both sides and chloride ions are like bulky trucks stuck in the traffic with no space to move.

Banerjee and PhD student Jingxiang Cheng built a “superhighway” for the ions to move by adding tiny amounts of calcium, magnesium or strontium to the atomic structure of lanthanum oxychloride. They found adding calcium helped the chloride ions go as much as 10,000 times faster.

The ultrabright X-rays at the CLS helped the team understand how the additional ingredients made the chloride structure “softer,” helping ions squeeze through a battery’s solid electrolyte and store more energy. The results were published in ACS Applied Energy Materials.

“We are exploring uncharted territory,” says Cheng, who is completing his PhD at Texas A&M University. “We're expanding the horizon of the battery field and we're hoping to use this platform to build more on it, and to explore things that lithium-ion batteries are not super good at.” 

Banerjee and Cheng say this research would not have been possible without access to the CLS – especially the VLS-PGM beamline. “It (the beamline) is really one of the few places in the world that you can make these sorts of measurements,” says Banerjee.

The successful transition from fossil fuels to clean energy demands new solutions for energy storage. “We've done this work to see if we can basically start building the foundations for new types of battery energy storage that will be more sustainable and especially for large scale,” said Banerjee.

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Cheng, Jingxiang, Victor Alexander Gomez, Alice R. Giem, Carlos A. Larriuz, Samuel Franz Gatti, Adrian F. Silva, Lucia Zuin, Sigita Trabesinger, and Sarbajit Banerjee. "Site-Selective Modification of Lanthanum Oxychloride to Modulate Halide-Ion Conduction." ACS Applied Energy Materials (2026). https://doi.org/10.1021/acsaem.6c00392

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Canadian Light Source
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