July 21st, 2017 by Tina Casey
The US Department of Energy has been celebrating Made in America Week in its own special way, with loads of good news about renewable energy and clean tech. The latest addition to the list is a “sodium battery” energy storage breakthrough from Brookhaven National Laboratory. It’s great news for the US wind and solar industries but it could send a chill through the spine of lithium-ion battery fans.
Wind And Solar Luv Energy Storage
The US wind and solar industries began to ratchet up during the Obama Administration, and at that time the main criticism was that the wind and the sun are intermittent and should not be counted as reliable sources of electricity in national energy policy.
Well, that was then. In the past few years the energy storage market has exploded, providing a way to bridge dark nights and doldrums.
That’s both a solution and a problem. The problem is that rechargeable lithium-ion batteries are the main energy storage platform in use today for everything from cell phones to electric vehicles, on up to grid scale battery arrays.
The spiking demand is raising price and supply chain issues, and the Energy Department is among those looking for new, better and cheaper ways to sustain the energy storage revolution.
Here Comes The Sodium Battery
One new energy storage material with great promise is sodium — one of the two main ingredients in common table salt — and the Energy Department’s Brookhaven National Laboratory has teamed up with the Chinese Academy of Sciences to take the technology a “decisive” step closer to commercialization.
Energy planners like the idea of sodium because it is cheap, plentiful, and non-toxic. But, there are a number of good reasons why we don’t have sodium batteries today. Brookhaven explains one of them:
…a typical battery’s cathode is made up of metal and oxygen ions arranged in layers. When exposed to air, the metals in a sodium battery’s cathode can be oxidized, decreasing the performance of the battery or even rendering it completely inactive.
The Brookhaven Factor
If the new breakthrough leads to the sodium battery of the future, US taxpayers will get to do a giant group hug.
That’s because the collaboration with China involved the use of a facility at Brookhaven called the National Synchrotron Light Source II.
So, we collectively own “one of the newest and most advanced synchrotron facilities in the world:”
NSLS-II will enable the study of material properties and functions with nanoscale resolution and exquisite sensitivity by providing world-leading capabilities for X-ray imaging and high-resolution energy analysis.
…NSLS-II provides the research tools needed to foster new discoveries and create breakthroughs in critical areas such as energy security, environment, and human health.
The Sodium Battery Breakthrough
China’s part of the collaboration involved tweaking the cathode to introduce different materials, and positioning those materials at different intervals.
They used NSLS-II to compare their new versions with conventional sodium battery structures.
NSLS-II provides researchers with different types of beamlines. The group used the Inner-Shell Spectroscopy beamline to analyze their samples.
This particular beamline enables researchers to hit materials with an “ultra-bright x-ray beam” and track how light is absorbed and re-emitted. For energy storage analysis, it provides a real-time process for measuring changes in the battery when it’s charging and discharging.
Here’s the explainer from Brookhaven physicist Eli Stavitski:
We use the beamline to determine how metals in the cathode material change oxidation states and how it correlates with the efficiency and lifetime of the battery’s structure.
The results of the study showed that the new materials developed by China’s research team yielded a more stable battery.
You can get all the details under the title, “Designing Air-Stable O3-Type Cathode Materials by Combined Structure Modulation for Na-Ion Batteries” from the Journal of the American Chemical Society. For those of you on the go, here’s a snippet from the abstract:
Herein, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level…Such a simple and effective structure modulation reveals a new avenue for high-performance O3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.
Got all that?
The team found that their new battery structure “exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles.”
To ice the energy storage cake, the researchers found that there was no loss of capacity when the battery was dunked in water.
No word yet on performance under very hot and cold conditions, but hold that thought for next steps.
Look for more energy storage news from Brookhaven in the future — apparently this is the first time that the lab’s ISS beamline was used to study a battery, and the promising results are likely to attract other researchers.
More Good News From The Energy Department
US Energy Secretary Rick Perry is a longtime advocate for wind power, and as former Governor of Texas — a red hot center of US wind energy development — he was perhaps miffed that the US wind industry did not get a shout-out from President Trump during the Made in America Week publicity event.
Perry took it upon himself to fill in the gap. He started the week off with a widely circulated tweet promoting wind turbine manufacturing in 40 US states. At the beginning of the week his agency also made a huge announcement about biofuel, which is another renewable energy industry with a growing foothold in Texas (that includes algae biofuel btw).
The Energy Department’s National Renewable Energy Laboratory has been celebrating its 40th anniversary this year, and it used the occasion of Made in America Week to toot its contributions to the US economy, too. A tweet about solar (yet another renewable energy resource of which Texas has plenty) links to this new infographic from NREL: