Rock Salt May Lead The Way To Better Batteries

The regular refrain here when it comes to announcements of new battery chemistries hailed as potentially miraculous is that if we had a pound, dollar, or Euro for each one we’ve heard, by now we’d be millionaires. But still they keep coming, and it’s inevitable that there will one or two that break through the practicality barrier and really do deliver on their promise. Which brings us tot he story which has come our way today, the suggestion that something as simple as rock salt could triple the energy density of a lithium-ion vehicle battery.

The research led from Lawrence Berkeley National Laboratory started around the use of cobalt in the battery cathode, an expensive and finite resource with the added concern of being in large part a conflict mineral from the Democratic Republic of Congo. Cobalt is used in  the cathodes because its oxide crystals form a stable layered structure into which the lithium ions can percolate. Alternative layered-structure metal oxides perform less well in retaining the lithium ions, making them unsuccessful substitutes. It seems that the three-dimensional structure of a rock salt crystal performs up to three times better than any layered oxide, which is where the excitement comes from.

Of course, if it were that simple we’d all be using three-times-more-powerful, half-price 18650s right now, which of course we aren’t. The challenge comes in making a rock salt cathode which both holds the lithium ions, and keeps that property reliably over the thousands of charge cycles needed for a real-world application. This one may yet be anther dollar on that metaphorical pile, but it just might give us the batteries we’ve been looking for.

Then again, when you’re looking at exciting battery chemistry, why limit yourself to lithium?

Will Nickel-Hydrogen Cells Be The Energy Storage Holy Grail?

You may have heard us here remarking in the past, that if we had a pound, dollar, or Euro for every miracle battery technology story we heard that was going to change the world, we would surely be very wealthy by now. It’s certainly been the case that many such pronouncements refer to promising chemistries that turn out only to be realizable in a lab, but here there’s news of one with a bit of pedigree. Nickel hydrogen batteries have a long history of use in space, and there’s a startup producing them now for use on the ground. Could they deliver the energy storage Holy Grail?

The cathode in a nickel-hydrogen battery is formed by nickel hydroxide, and the anode is formed of hydrogen. If a gas as an anode sounds far fetched, we’re guessing that their structure is similar to the zinc-air battery, in which zinc hydroxide forms in a paste of powdered zinc, and works against oxygen from the air over a porous conductive support. What gives them their exciting potential is their ability to take more than 30,000 charge/discharge cycles, and their relative safety when compared to lithium ion cells. Hydrogen in a pressure vessel might not seem the safest of things to have around, but the chemistry is such that as the pressure increases it reacts to form water. The cost of the whole thing is reduced further as new catalysts have replaced the platinum used by NASA on spacecraft.

We really hope that these batteries will be a success, but as always we’ll wait and see before calling it. They may well be competing by then with the next generation of zinc-air cells.

Aluminum Battery Is Sustainable

If you think of metals in a battery, you probably think of lithium, mercury, lead, nickel, and cadmium. But researchers in Australia and China want you to think about aluminum. Unlike most battery metals, aluminum is abundant and not difficult to dispose of later.

Their battery design uses water-based electrolytes and is air-stable. It is also flame retardant. The battery can provide 1.25V at a capacity of 110 mAh/g over 800 charge cycles. The idea of using aluminum in a battery isn’t new. Aluminum is potentially more efficient since each aluminum ion is equivalent to three lithium ions. The batteries, in theory, have higher energy density compared to lithium-ion, but suffer from short shelf life and, so far, practical devices aren’t that close to the theoretical limits of the technology.

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Determining The Size Of The New US Lithium Deposit Amidst Exploding Demand

With demand for lithium in the world market projected to increase by 2040 to as much as eight times the demand in 2022, finding new deposits of this metal has become a priority. Currently most of the world’s lithium comes from Australia, Chile, China and Argentina, with potential new mining sites under investigation. One of these sites is the McDermitt caldera in the US, a likely remnant of the Yellowstone hotspot and resulting volcanic activity. According to a recent study (Chemistry World article) by Thomas R. Benson and colleagues in Science Advances, this site may not only contain between 20 to 40 million tons of lithium in the form of the mineral clay illite, but was also formed using a rather unique process.

This particular group of mineral clays can contain a number of other chemicals, which in this particular case is lithium due to the unique way in which the about 40 meter thick layer of sediment was formed. Although lithium is a very common metal, its high reactivity means that it is never found in its elementary form, but instead bound to other elements. Lithium is thinly distributed within the Earth’s crust and oceans. Incidentally, the Earth’s oceans contain by far the largest amount of lithium, at approximately 230 billion tons.

So how much lithium could be extracted from this new area, and how does this compare to the increasing demand?

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Zinc-Air, The Next Contender In Vehicle Batteries?

If you’ve got an interest in technology, it’s inevitable that your feed will feature a constant supply of stories with titles in the vein of “New battery breakthrough offers unlimited life and capacity!”. If we had a pound, dollar, or Euro for each one, we’d be millionaires by now. But while the real science behind the breathless headlines will undoubtedly have provided incremental battery improvements, we’re still waiting for the unlimited battery.

It’s not to say that they don’t conceal some interesting stories though, and there’s an announcement from Australia proving this point admirably. Scientists at ECU in Perth have created a new cathode compound for rechargeable zinc-air batteries, which it is hoped will make them much safer and cheaper competitors for lithium-ion cells.

Most of us think of zinc-air batteries as the tiny cells you’d put in a camera or a hearing aid, but these conceal a chemistry with significant potential that is held back by the difficulty of creating a reliable cathode. In these batteries the cathode is a porous support in which a reaction between zinc powder wet paste and oxygen in the air occurs, turning zinc into zinc oxide and releasing electrons which can be harvested as electricity. They have a very high power density, but previous cathode materials have quickly degraded performance when presented with significant load.

The new cathode support is a nano-composite material containing cobalt, nickel, and iron, and is claimed to offer much better performance without the degradation. Whether or not it can be mass-produced remains to be seen, but as a possible alternative to lithium-ion in portable and transport applications it’s of great interest.

Off-Grid EV Charging

There are plenty of reasons to install solar panels on one’s home. Reducing electric bills, reducing carbon footprint, or simply being in a location without electric service are all fairly common. While some of those might be true for [Dominic], he had another motivating factor. He wanted to install a charger for his electric vehicles but upgrading the electric service at his house would have been prohibitively expensive. So rather than dig up a bunch of his neighbors’ gardens to run a new service wire in he built this off-grid setup instead.

Hooking up solar panels to a battery and charge controller is usually not too hard, but getting enough energy to charge an EV out of a system all at once is more challenging. The system is based on several 550W solar modules which all charge a lithium iron phosphate battery. The battery can output 100 A DC at 48 V which gives more than enough power to charge an EV. However there were some problems getting this much power through an inverter. His first choice let out the magic smoke when it was connected, and it wasn’t until he settled on a Growatt inverter capable of outputting 3.5 kW that the system really started to take shape.

All of this is fairly straightforward, but there’s an extra touch here that makes this project noteworthy. [Dominic] wanted to balance incoming power from the photovoltaic system to the current demands from the EVs to put less strain on the battery. An ESP32 was programmed to only send as much power to the EVs as the solar system is producing at any given time, and also includes some extra logic to make sure the battery doesn’t drain itself from the idle power requirements of the inverter. Right now the system works well but the true test will be when it goes through its first winter. Even though solar panels are more efficient at colder temperatures, if the amount of sunlight or the angle of the panels aren’t ideal there is generally much less production.

Liquid Metal Battery Goes Into Production

The news is rife with claims of the next great thing in clean energy generation, but most of these technologies never make it to production. Whether that’s due to cost issues, production, or scalability, we’re often teased with industry breakthroughs that never come to fruition. Multi-layered solar panels, wave and tidal energy, and hydrogen fuel cells are all things that are real but can’t seem to break through and overtake other lower cost, simpler, and proven technologies. One that seems to be bucking this trend is the liquid metal battery, which startup Ambri is putting into service on the electrical grid next year.

With lithium ion battery installations running around $405 per kilowatt-hour, Ambri’s battery technology is already poised to be somewhat disruptive at a cost of about half that. The construction method is simpler than lithium as well, using molten metal electrodes and a molten salt electrolyte. Not only is this more durable, it’s also not flammable and is largely immune to degradation over time. The company’s testing results indicate that after 20 years the battery is expected to still retain 95% of its capacity. The only hitch in scaling this technology could be issues with sourcing antimony, one of the metals needed for this type of construction.

Even though Ambri can produce these batteries for $180 to $250 per kilowatt-hour, they need to get the costs down to about $20 for the technology to be cost-competitive with “base load” power plants (an outdated term in itself). They do project their costs to come down significantly and hit this mark by 2030, which would put electrical grids on course to be powered entirely by renewables. Liquid metal batteries aren’t the only nontraditional battery out there trying to solve this problem, though. Another promising interesting energy storage technology on the horizon is phase-change materials.