World's First Anode-Free Sodium Solid-State Battery Unveiled by Scientists

Although sodium batteries, solid-state batteries, and anode-free batteries are individually known concepts, so far, no one has successfully combined these three concepts. Recently, a breakthrough has been achieved by a research team from the Pritzker School of Molecular Engineering at the University of Chicago and the Department of Chemistry and Nanoengineering at the University of California, San Diego. Together, they have developed the world's first anode-free sodium solid-state battery. This research was recently published in the journal "Nature Energy," revealing the structure of this new sodium battery, capable of hundreds of stable cycles. By removing the negative electrode and using inexpensive and abundant sodium instead of lithium, the production cost of this new battery is lower, with a reduced environmental impact. Thanks to its innovative solid-state design, the battery's safety and durability have been significantly enhanced.

To manufacture a sodium battery with energy density comparable to lithium batteries, the research team devised a novel battery structure. Traditional batteries require an anode to store ions during charging, with ions flowing from the anode through the electrolyte to the cathode during use, providing power to various devices and vehicles.

Anode-free batteries eliminate the anode component, directly storing ions on a metal deposited electrochemically in the electrolyte. This design allows the battery to achieve higher voltage and lower costs, enhancing energy density, but also introducing its own challenges.

These liquid electrolytes, while stably consuming the active material, form a substance over time known as the solid electrolyte interface (SEI), which degrades the battery's efficiency.

The research team has employed an innovative approach to address this challenge. They designed a current collector surrounding the electrolyte, a departure from the traditional approach where the current collector is typically enveloped by the electrolyte. By compacting aluminum powder under high pressure, they created a solid conducting body around the electrolyte, maintaining contact similar to a liquid, enabling low-cost, high-efficiency cycling.