Take These Batteries with Grains of Sodium

Dean Sigler Batteries, Electric Powerplants, Sustainable Aviation Leave a Comment

“The goal of the Laboratory for Energy Storage and Conversion (LESC), at the University of California San Diego Nanoengineering Department, is to design and develop new functional nano-materials and nano-structures for advanced energy storage and conversion applications.”  Their focus on sodium (salt) batteries seems to promise much.

UC San Diego is carrying out that mission with new and different approaches to creating “safer and less expensive alternatives to lithium ion batteries.”  One such approach is commercializing an advanced sodium ion battery using a tin anode instead of hard carbon.

Cost, of course, is a major factor in turning to sodium.  OneCharge lists the comparative prices of lithium and sodium precursors as of June, 2023:

The same source notes sodium is 1,180 times more abundant in the earth than lithium.

UCSD researchers Darren H.S. Tan and Erik A. Wu have responded to these numbers with an “advanced sodium ion battery using a tin anode instead of hard carbon.  Energy density of the new cells competes with, and even exceeds, that of lithium iron phosphate (LFP) batteries.  Developers promote the cells’ chemistry ability to extend battery life while using low-cost, readily available materials.

Wu, Chief Technology Officer for the firm, says their use of a tin alloy anode “Overcomes the common failure modes of silicon, such as particle cracking from volume expansion, active material losses, and capacity degradation,”

Their startup, UNIGRID, suggest a ground-bound application at grid level. But being comparable to LFP cells puts their batteries at the lower level of potential vehicle use.  Who knows what further developments will bring?

Less is More Airworthy

Coming from the same University in a collaboration with the University of Chicago Pritzker School of Molecular Engineering, comes a battery that removes the anode and stirs up a mix of sodium and aluminum powder.

Interesting Engineering explains the battery in an interesting way.  “The design uses aluminum powder, flowing like liquid, compressed under high pressure to form a solid collector with liquid-like contact with the electrolyte.”

Comparison of different batteries.  Note the current collector stays the same relative size for all variants.

The publication continues, “The team’s design uses a stable solid electrolyte and pressure to form dense sodium metal. An aluminum current collector ensures efficient, repeatable sodium plating and stripping at high capacities and speeds.

“This new type of battery will be less expensive and less harmful to the environment since the anode will be removed, and sodium, which is cheap and plentiful, will be used instead of lithium.”

In the Ted Talk, Dr. Shirley Meng shares an overview of what her colleagues and students are doing with sodium ion batteries – among other worthwhile projects.

The team envisions a future in which a variety of clean, affordable batteries store renewable energy tailored to society’s needs.

The details of the research done by members from the University of Chicago Pritzker School of Molecular Engineering and the University of California San Diego were published in the July 3, 2024 issue of the journal Nature Energy.

“Design principles for enabling an anode-free sodium all-solid-state battery” was written by a fairly large group, including:

Their abstract for the paper covers the general idea, and the paper itself is hidden behind a paywall.  Ask your local technical librarian for access.

“Anode-free batteries possess the optimal cell architecture due to their reduced weight, volume and cost. However, their implementation has been limited by unstable anode morphological changes and anode–liquid electrolyte interface reactions. Here we show that an electrochemically stable solid electrolyte and the application of stack pressure can solve these issues by enabling the deposition of dense sodium metal. Furthermore, an aluminium current collector is found to achieve intimate solid–solid contact with the solid electrolyte, which allows highly reversible sodium plating and stripping at both high areal capacities and current densities, previously unobtainable with conventional aluminium foil. A sodium anode-free all-solid-state battery full cell is demonstrated with stable cycling for several hundred cycles. This cell architecture serves as a future direction for other battery chemistries to enable low-cost, high-energy-density and fast-charging batteries.”

If vital materials are saved for the most necessarily light weight applications, many of the demands on the lithium market will be reduced.  Recent discoveries of lithium deposits on the south-east border of Oregon and Nevada may help.  In the meantime, advancing the use of more common safer elements may enable broader use and greater consumer acceptance.  With groups like LESC exploring new technologies, we may end up with better batteries and brighter future.

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