Donald Robert Sadoway is a renowned expert on batteries, having done significant research on improving the performance and longevity of portable power sources.
A professor emeritus of materials chemistry at the Massachusetts Institute of Technology with more than 20 peer-reviewed published articles, Sadoway believes the rechargeable battery industry is concentrating its efforts in the wrong direction.
He has an alternative ready at hand; fast-charging aluminium-chalcogen batteries.
In this article:
- On the edge
- Overcoming the capital barrier
- Lithium-ion unfit for large-scale applications
- Fast-charging aluminium-chalcogen batteries
On the edge
These days, technology is moving at a breakneck pace. Novel cutting-edge innovations emerge, only to be one-upped by the next iteration within months or just a handful of years.
Battery technology is no exception. The last couple of years has seen an explosion of innovation and capital investment in battery chemistries, either improving lithium-ion or attempting to usurp it all together.
There’s a catch, however.
While technology continues to accelerate, the market lags, unable to keep up with rapidly changing infrastructure, manufacturing and supply chain requirements – especially given how close to the margin most industries run their resource chains.
In pharmacology and biotech, it’s said it takes at least 10 years for a new treatment to hit market shelves – with more complex technology like battery chemistries, it’s more like 20 years.
What’s more, the market is actively averse to change, with strong capital incentives to continue using the transportation methods, plants and mines that have already been heavily invested into over the years.
Lithium-ion is an excellent example of this phenomenon – in more ways than one.
Overcoming the capital barrier
Lithium-ion battery chemistry was first conquered by Sony some 30 years ago.
“If you go back to the 1990s, the dominant form of rechargeable battery chemistry was nickel metal hydride,” Professor Sadoway recalled in an interview with Proactive.
Sony was mostly building personal or home devices at the time – televisions, phones, Walkmans and a new line of handheld cameras that desperately needed a better power source.
“It was Sony that put the last pieces of the puzzle together to figure out how to make lithium-ion work,” Professor Sadoway said.
“They went to all the big manufacturers and showed them the new battery chemistry, offered to buy tens of millions of dollars’ worth of batteries, and every one of the manufacturers declined.”
The manufacturers had invested too much in nickel metal hydride battery factories – factories that were not capable of producing lithium-ion chemistries.
“Sony took the unprecedented step of manufacturing the batteries themselves – they could have easily passed on it, they weren’t a battery company at the time," Sadoway explained.
“But they didn’t, they took a chance, and today it’s the dominant form of rechargeable batteries.”
That kind of risk-taking is surprisingly rare in the energy and technology industry. It’s simply too expensive to try something unproven and potentially waste the invested capital – capital that could’ve been accumulating elsewhere.
For Sadoway, the inertia of dominant battery chemistries is a frustrating barrier to innovation.
“People have no imagination. They’re risk-averse. They just repurpose things.”
Lithium-ion unfit for large-scale applications
Lithium-ion batteries were originally designed for small, handheld or portable devices, the kind of products Sony was making at the point they were first manufactured.
While they’re perfect for these kinds of small-scale applications, Sadoway argues they’re simply not the right fit for larger uses.
“I mean, lithium-ion is fantastic, it’s given us the modern world, the laptop computer, smartphones and so on – but it was never intended to go into automobiles and certainly never intended for massive grid-scale storage,” he said.
There are two main issues (among many minor ones) related directly to chemical composition with large-scale lithium-ion batteries - scalability and longevity.
The first - scalability, or range potential, if you prefer - speaks to general anxieties around electric vehicles, specifically range anxiety and concerns with being stranded with nowhere to charge.
“Up until now, manufacturers addressed range anxiety by putting larger and larger battery packs in the vehicle, but you end up chasing your tail because you need more capacity to make up for the extra weight – you’re using the energy stored into the battery, simply to move the battery itself,” Sadoway explained.
“The alternative to larger and larger battery packs is the ability to charge rapidly.
“The dirty secret with lithium is that you shorten the battery’s life every time you use it – a 10-year battery life assumes perfect conditions, no stresses.
“If you want to fast charge, you can do it, but every time you do it accelerates the degradation of the cells.”
Those aren’t the only problems plaguing lithium-ion chemistries, however; the batteries are also volatile, representing a significant fire hazard under the wrong circumstances, and the materials to make them are expensive, carbon-intensive to produce, and rare.
Sadoway has made a career out of improving performance and longevity of batteries and portable power sources – he’s published papers on liquid metal batteries, polymer electrolytes, CO2 conversion and myriad lithium-ion chemistries.
It’s no surprise, then, that his work led him to design alternatives to lithium-ion batteries, specifically for applications he considers them unsuitable for.
Read more: Challengers emerge: alternatives to lithium-ion batteries
Fast-charging aluminium-chalcogen batteries
Sadoway’s design philosophy was centred specifically on solving the cost, safety and versatility constraints associated with lithium-ion batteries.
“It was the constituents, the components, that made aluminium–chalcogen batteries interesting,” Sadoway recalled.
“The battery had to have comparable performance to lithium-ion, without the threat of fire – because lithium-ion uses volatile flammable electrolytes and organic liquid.
“So, I said, ‘that’s forbidden’. It also had to be much, much cheaper.
“Those were my design parameters.”
Sadoway settled on aluminium for the negative electrode and sulphur (a type of chalcogen) for the positive.
“For the electrolyte, we looked at a class of low-melting molten salts that contain aluminium chloride. One of the components is sodium chloride – table salt – extremely abundant.”
Aluminium, sulphur and salt. Widely available, cheap materials with established supply chains.
The new battery chemistry also solves lithium-ion’s thermal runaway safety concerns, capable of running at extremely high temperatures.
“In the paper, we cite responses, vapour pressures and other physical properties going up well beyond 200 degrees Celsius,” Sadoway said, referring to his peer-reviewed paper on aluminium-chalcogen batteries in the leading science journal, Nature.
Read: Fast-charging aluminium–chalcogen batteries resistant to dendritic shorting
“We even looked at something as high as 500 degrees, which is the kind of temperature you have in a combustion engine today.”
So, what about performance? Lithium-ion has been mostly unchallenged in the portable battery arena thus far due to the material’s high energy density.
“The battery can produce about 529 watthours per litre, which is comparable to NMC (nickel-manganese-cobalt) lithium-ion batteries, which get about 540 watthours per litre depending on who’s numbers you look at,” Sadoway explained.
“The point is people aren’t being forced to take a big haircut. It’s safe, the materials are easily and ethically sourced, and the battery can charge and discharge very quickly – about 18 seconds, incredibly quick.”
That incredibly fast charging time addresses the second major issue with lithium-ion – range.
“Let’s say you can only go 100 miles, but you can charge it in, say 10 minutes while you’re on the road,” Sadoway outlined.
“You could recharge the battery in a similar time to refuelling your combustion engine tank.”
Which leaves the questions of degradation.
“We have data battery cells that have done 5,000 cycles over five years in the lab,” Sadoway chuckled.
“If you did a deep discharge once a day, every day for 5,000 cycles, that’s 13 years, and the cell has retained 99% of nameplate capacity.”
The only downside to these batteries appears to be temperature related - maintaining the salt in a molten state requires temperatures of about 65 degrees Celsius, although Sadoway thinks that can be brought down to 37 degrees - human body temperature.
The batteries maintain their temperature by being charged and discharged, meaning giving it a run around the block now and then would likely be more than enough to maintain the battery in above-freezing climates.
Most lithium batteries are limited to between 60 degrees Celsius to minus 10 degrees Celsius, meaning aluminium-chalcogen batteries still have a much larger temperature range.
So, fast-charging aluminium-chalcogen batteries have comparable performance, cheaper components and longer and more efficient battery life – surely someone wants to build them?
“People ask me, ‘are you being pursued by legacy battery makers?’ No, no one calls me, they don’t want to take a chance,” Sadoway said.
“They’ve got big order books full of commitments from automobile companies, so why tinker with something new?
“They're already concerned about getting heavily invested into the battery metals of today – nickel, manganese, cobalt and of course, lithium – and they wonder if something is coming around the corner.
“There’s room for innovation, but the industry is risk-averse.”
While the industry might not be ready for the cutting-edge of new battery chemistry technology, as Sony’s lithium-ion batteries proved, it only takes one company with capital and a vision to turn an entire industry on its head.
Whether it’s aluminium-chalcogen, dual carbon, sodium-ion or any number of other chemistries being developed for battery technology, it seems unlikely that any single chemistry will replace lithium-ion – rather, we may find ourselves in a new era of purpose-built chemistries, with a different composition for every application. Only time will tell.