Breakthrough in Sodium Battery Chemistry Promises Lower Costs

• Osaka Metropolitan University researchers have developed a mass synthesis process for sodium-containing sulfides.
• The new process yields solid sulfide electrolyte with the world's highest reported sodium ion conductivity and glass electrolyte with high formability.
• Mass synthesis of such electrolytes with high conductivity and formability is key to the practical use of all-solid-state sodium batteries.

Osaka Metropolitan University researchers have developed a mass synthesis process for sodium-containing sulfides. Mass synthesis of electrolytes with high conductivity and formability is key to the practical use of all-solid-state sodium batteries, thought to be safer than lithium-ion batteries and less expensive, as sodium is far more plentiful than lithium.

The report discussing the discovery results has been published in the journal Energy Storage Materials and Inorganic Chemistry. The researchers developed a process that can lead to mass synthesis yields solid sulfide electrolyte with the world’s highest reported sodium ion conductivity and glass electrolyte with high formability.

Synthesized material for all-solid-state sodium batteries. The synthesized solid sulfide electrolyte Na2.88Sb0.88W0.12S4 has the world’s highest reported sodium ion conductivity. Image Credit: Atsushi Sakuda, Osaka Metropolitan University. Click here for the largest image at the press release page.

The pursuit of greener energy also requires efficient rechargeable batteries to store that energy.

While lithium-ion batteries are currently the most widely used, all-solid-state sodium batteries are attracting attention as sodium is far more plentiful than lithium. That should make sodium batteries less expensive, and solid-state batteries are thought to be safer, but processing issues mean mass production has been difficult.

Osaka Metropolitan University Associate Professor Atsushi Sakuda and Professor Akitoshi Hayashi, both of the Graduate School of Engineering, led a research team in developing a process that can lead to mass synthesis for sodium-containing sulfides.

Using sodium polysulfides (sulfides with two or more atoms of sulfur) as both the material and the flux, which promotes fusion, the team created a solid sulfide electrolyte with the world’s highest reported sodium ion conductivity — about 10 times higher than required for practical use — and a glass electrolyte with high reduction resistance.

Mass synthesis of such electrolytes with high conductivity and formability is key to the practical use of all-solid-state sodium batteries.

Professor Sakuda commented. “This newly developed process is useful for the production of almost all sodium-containing sulfide materials, including solid electrolytes and electrode active materials.  Also, compared to conventional methods, this process makes it easier to obtain materials that display higher performance, so we believe it will become a mainstream process for the future development of materials for all-solid-state sodium batteries.”

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If this development can get the sodium battery chemistry into mass production it will be a sea change in the costs for many of the popular electronics. That’s because the battery is a major cost component in many devices, especially the lower cost ones.

Let's hope this tech gets the sodium technology closer to the mass market.

By Brian Westenhaus via New Energy and Fuel

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