Team develops world’s first anode-free sodium solid-state battery

LESC believes the research brings forward the reality of inexpensive, fast-charging, high-capacity batteries for electric vehicles and grid storage. Their findings, detailed in Nature Energy, demonstrate a new sodium battery architecture with stable cycling for several hundred cycles.

“Although there have been previous sodium, solid-state, and anode-free batteries, no one has been able to successfully combine these three ideas until now,” said UC San Diego PhD candidate Grayson Deysher, first author of the paper.

LESC said that by removing the anode and using sodium instead of lithium, this new battery will be more affordable and environmentally friendly to produce. Through its solid-state design, the battery also will be safe and powerful.

To create a sodium battery with the energy density of a lithium battery, the team needed to invent a new sodium battery architecture.

Traditional batteries have an anode to store the ions while a battery is charging. While the battery is in use, the ions flow from the anode through an electrolyte to a cathode.

Anode-free batteries store ions on an electrochemical deposition of alkali metal directly on the current collector. This approach enables higher cell voltage, lower cell cost, and increased energy density, but comes with challenges.

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“In any anode-free battery there needs to be good contact between the electrolyte and the current collector,” said Deysher. “This is typically very easy when using a liquid electrolyte, as the liquid can flow everywhere and wet every surface. A solid electrolyte cannot do this.”

However, liquid electrolytes create a buildup of solid electrolyte interphase while steadily consuming the active materials, reducing the battery’s usefulness over time.

To overcome this, the team created a current collector from aluminium powder, which flows like a liquid, to surround the electrolyte.

During battery assembly the powder was densified under high pressure to form a solid current collector while maintaining a liquid-like contact with the electrolyte, enabling the low-cost and high-efficiency cycling.

“Sodium solid-state batteries are usually seen as a far-off-in-the-future technology, but we hope that this paper can invigorate more push into the sodium area by demonstrating that it can indeed work well, even better than the lithium version in some cases,” said Deysher.

Deysher and Prof. Y. Shirley Meng, University of Chicago Pritzker School of Molecular Engineering and principal investigator at LESC, have filed a patent application for their work through UC San Diego’s Office of Innovation and Commercialization.