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Study identifies main culprit behind lithium metal battery failure (ucsd.edu)
101 points by clouddrover 49 days ago | hide | past | web | favorite | 56 comments

If they can get close to that doubling of the energy density of Li-ion they're claiming, that'd make a _big_ difference to the electric passenger flight space. Possibly a game changing difference. Way more significant I think than doubling electric car range (or halving electric car battery weight/cost).

You aren't wrong about that. The problem current prototypes have is range is limited especially when you include 'reserve fuel' requirements. If the aircraft can only fly for an hour and you need 30-45 minutes reserve you only can fly for 15-30 minutes. Double that and now you can fly for 75 to 90 minutes.

Assuming 300 mph. The first case gives you an effective range of 75 to 150 miles. Second case gives you 375 to 450 miles range. That's 3 to 5 times more effective range.

Go on google earth and start drawing 450 mile radius circles around population centers. Yeah that.

Bonus: Eviation is claiming an estimate of 650 miles range with their yet to fly Alice.

The two big advantages with electric flight are fuel costs and maintenance costs. For electric the fuel cost is a third to a quarter lower. And electric motors should have a much longer service life and lower maintenance needs than turbo props.

There's a slight disadvantage for electric planes when it comes to "refueling" times for those ~1000kWh batteries. This may be worked around in multiple ways like (very) fast charging or battery swaps. But without this you'd have a pretty bad turnaround time.

For small planes like the Eviation, a lot of the market is private and charter, which probably don't need really fast turnaround anyway.

But yeah, to make a big carbon impact, electric planes would definitely need fast turnaround.

>which probably don't need really fast turnaround anyway.

Most charter flights are just to fly to somewhere nearby, drop someone off, fly somewhere else pick someone else up, repeat. Often the destination is some small airport that doesn't have jet fuel (most charter aircraft are turboprops) so you need enough fuel for the return leg or you make a 30min detour to somewhere that does.

The hops are often small but you often need to do many of them back to back without a ton of downtime in between and usage patterns tend to be not well distributed (not much happens on a Tuesday but on a Friday every rich banker is trying to charter a flight to their house on Nantucket or wherever). It's basically the same usage pattern as an uber vehicle will see only the vehicle itself is a proportionately larger cost so you can't as easily just have more of them to make up for charging time (like some electric bus fleets do).

Charter flights are one of the last things I can see being electrified unless battery swaps become a thing because the charging time directly hits profitability.

> Assuming 300 mph.

I think that's a very generous assumption. Typical small engine light aircraft cruise at 70-120 knots (80-140 mph). Wikipedia[1] suggests 211 mph as the current electric speed record (made in 2017). I doubt typical aircraft will be as optimised for speed as the one that holds the record. Increased speed causes exponentially increased aerodynamic drag, so if you want to increase range, slower speed [than your maximum speed] is the way to do it, not faster.

[1] https://en.wikipedia.org/wiki/Extra_EA-300#Variants

Could a two step setup be of interest ? an external device or vehicle to to lift it up, then the internal battery takes care of sustained gliding in high altitude (low air density) ?

Even without an external lifting element there's plenty of history for towed launches for a little extra push. Aircraft carrier catapults and ground launched gliders come to mind.

yeah I had these in mind, the question is would it change the energy equation significantly

The effects of electric battry density is cumulative. A lot of the requirements come from hauling the battery. If the battery gets smaller, you also need a lot less energy

Yes that too, lower battery weight means the rest of the aircraft can be made lighter. It's been a long time since I've seen numbers but the effect is more significant than people would naively assume. As you increase the weight of component you need to also increase the wing area and the required power. Which itself adds weight.

We may have to revisit that rule for electrics.

Or one option is that we normally don’t let li-ion batteries discharge completely to preserve battery life but that could still count toward your reserve with the right software.

Or I believe there are some existing one time use batteries that are way more entry dense than li-ion? Perhaps those could be part of the system just for emergency use and to meet reserve requirements.

So, avgas has about 45 MJ/kg energy density, lithium ion batteries have 0.5 MJ/kg. Aviation engines are maybe 30% efficient, while electrics are about 90% efficient, so we've got about 15 MJ/kg usable versus 0.45 MJ/kg usable. Double the energy density of a lithium battery, and you're at 0.9 MJ/kg usable, versus 15.

We're not there yet to propel airplanes with batteries, not useful ones, anyway.

That's not the right analysis at all. Imagine if you did the same math for avgas in a world where some other fuel does 100 MJ/kg. You'd declare "We're not there yet to propel airplanes with avgas, not useful ones, anyway".

You don't have to outperform existing solutions to have a viable product. Price and other factors can easily swamp a particular performance stat. Different performance will lead to different use cases, but that is in no way the same as zero use cases.

I guess we can sum it up as "it can't replace everything (yet)".

The current planes fly enormous distances - 15000 km - without refueling. (And there is not a lot od evidence that even this is fuel mass limited.) There are a lot of 2000 km routes to be replaced, like most countries' domestic flights.

But yep, it's not a solution for keeping our current flying habits. We will have to cut down on flying, a lot.

Actually, the range of current planes is absolutely fuel mass limited. The 777-LR, which can reach these distances, carries up to 145 000 kg of fuel. This is 42% of its maximal take-off weight [1]. As a result of added weight for longer distances, planes use the least amount of fuel/km on flights of 2500 km, despite the extra fuel used to take off [2]

An electric plane flying 2000 km as opposed to 15 000 km would require an even larger proportion of their take of weight as batteries, and would thus not be able to carry a lot of passengers/cargo on such a relatively short flight. It will require a fundamental breakthrough to make passenger flights of that distance economically feasible.

[1] https://en.wikipedia.org/wiki/Boeing_777#Specifications [2] https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#/medi...

If you solution to a problem is “massive reduction in critically important infrastructure”, then you might not have a solution.

Flying on such a huge scale is a relatively recent occurrence, very little of it is critical, the world isn't going to end because you can't holiday in Bali.

Airports are a part of every country’s critical infrastructure.

> the world isn't going to end because you can't holiday in Bali

Perhaps not. But the Balinese economy would simply collapse. I’m sure the Balinese economy is of critical importance to the ~4 million people who live there. What you’ve chosen as a contrived example doesn’t even illustrate your point.

On the other hand: https://www.worldcrunch.com/food-travel/how-mass-tourism-is-... perfectly illustrates the problems with your thinking.

My thinking doesn’t have anything to do with it, it’s simply a fact that 80% of Bali’s economy is tourism. An industry specifically promoted by the Indonesian government as a long standing policy.

“But, what if tourism wasn’t critical to the Balinese economy, what if they had instead spend the last 50 years developing a different industry” you might say. Well, who knows. But they didn’t, and the criticality of air travel to Bali is not up for any meaningful debate.

This argument doesn't hold much water. Sure, it might be technically correct for Balinese ecomomy. But lots of people fly lots of places for very capricious reasons. If vacation is the goal, then everyone can go on a trip a bit closer to home without flying. Certain major tourism centers will lose out, but on average, there will be just as many tourists, just in different places.

Air travel is far too cheap, everything else follows from that.

The majority of tourists to Bali are from Australia. Bali is the closest to home they can go without going to NZ (similar to Australia) or staying in country (ignore Papua New Guinea as too dangerous).

Planes make Australia a lot more viable, since it’s such a huge sparsely populated island that even a lot of domestic travel is better in the air. Bali and Indonesia’s various small distributed islands are much more dense, but island hopping by boat alone is also slow and unsuited to a lot of economic development.

Countries like Australia and Indonesia would take huge hits if air travel was a lot more expensive, much more so than America.

So we’ve gone from the idea that air travel wasn’t critical infrastructure, with Bali as the example, to essentially saying “but what if the world was completely different from the way it actually is”. Does that mean you agree that it is critical infrastructure?

> Air travel is far too cheap, everything else follows from that.

This is another outrageous claim. All aviation accounts for about 2% of global emissions.

The people commenting in this thread have chosen tourism, presumably because they think it’s the most frivolous source of aviation emissions. But even this is obviously critical to global economies. On top of that, the proposed solution amounts to complete economic isolationism. An idea I’m honestly surprised to see promoted on HN.

Suggesting that the world could possibly completely different from the way it actually is, and that the foundations of the global economy aren’t necessary isn’t suggesting a solution. It’s just utopian navel gazing.

That 2% figure is dubious, most reputable sources put it at 4%. On top of that the IPCC has estimated that the climate impact of aircraft is two to four times greater than the effect of their carbon dioxide emissions alone.

The 2% number is from the IPCC, and carbon emissions from planes have the same climate impact as carbon emissions from any other source (according to the IPCC). But just for the sake of argument, let’s say the number is much higher than that. Let’s say it was 10%, 5x higher than the IPCC claims it is. It still poses a negligible impact to the climate, and has the least ROI or any of the major contributors to carbon emissions. Electricity consumption is by far the biggest contributor, and is by far the easiest to solve. If we were to solve those problems, there’d be no need to even worry about aviation at all. This idea that all carbon emissions are terrible and must be eliminated is entirely counter productive, and entirely impossible.

A special characteristic of aircraft emissions is that most of them are produced at cruising altitudes high in the atmosphere. Scientific studies have shown that these high-altitude emissions have a more harmful climate impact because they trigger a series of chemical reactions and atmospheric effects that have a net warming effect.

This is what the IPCC is referring to when they say the climate impact is two to four times greater than from emissions alone.

This idea that all carbon emissions are terrible and must be eliminated is entirely counter productive, and entirely impossible.

We have left it too late, our only choice now is to do everything we can. There is plenty of air travel which is of marginal economic benefit that we can drop.

Bali's largest city is at 4m elevation. The oceans are rising and the coral reefs around the island are dying. Bali has no economic future if we don't stop global warming.

Where’s the model that predicts a 4m sea level rise? Even the most outlandish predictions don’t come close to that.

But in any case, that’s largely irrelevant to my point. This argument presupposes that the only way to prevent catastrophic man-made climate change is to put an end to air travel. That’s such an outrageous thing to claim that you can’t simply act like it’s something that’s obvious true, and that everybody should already believe.

You don't need to have the city completely under water to make it effectively uninhabitable. It's sufficient if it floods regularly during storms. Global sea levels are expected to rise 0.5-1m at just 2° of warming. We're on an emissions trajectory that will cause much more severe warming.

We don't have to completely stop global air travel, but we have to make it significantly more expensive. The price to suck all the carbon out of the atmosphere again is not trivial. Long distance tourism will suffer from this.

Denpasar does flood regularly during storms. It always has.

But that aside, all aviation accounts for about 2% of global emissions, with tourism only being a portions of that. What is your basis for claiming that the only way to avoid catastrophic man-made climate change is to significantly reduce air travel? There are so many more ways to reduce emissions, with much higher ROIs, and much less economic impact. Electricity generation and land transport are so much easier to make renewable. The idea that the future of the world depends on reducing air travel is simply laughable.

We need to become completely carbon neutral in twenty years (at most!). Air travel shouldn't be our top priority, by far, but we need to address it too. Globally it has a small impact because almost nobody can afford it. But for a person in an industrialized nation the relative impact is quite big. When I travel from Germany to SF for example, I roughly double my climate impact for that year.

2% of CO2 emissions and growing. The impact is higher though. It's too difficult to trawl through the original literature on mobile; Wikipedia: The IPCC has estimated that aviation is responsible for around 3.5 percent of anthropogenic climate change, a figure which includes both CO2 and non-CO2 induced effects.


Aviationis growing rapidly, and it's effect on global warming is bigger than just the CO2 emissions due to other effects in atmosphere (2.5 is a commonly used weighing factor).

Combined with the fact that the global warming pie is made up of many small slices makes it one of the most significant slices of the pie.

> makes it one of the most significant slices of the pie

Which significant slice of the pie is it on this graph [0]? It’s a tiny slither of the transport one. Most of that graph is just electricity generation split into different categories.

[0] https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...

You can call a lot of things "critical infrastructure" but it doesn't mean we can't phase out many of those those things in an orderly fashion. It just means dependencies we've added to our life, many of which are very recent.

We have to make compromises, unless we prefer to lose the global warming battle. Humanity's benefits from cheap air travel are much less than losses from unchecked climate change.

This argument has absolutely no basis in economics. There is currently a particular demand for air travel. If you want to reduce that demand, you can only do one of the following things:

1. Create a competing product that people prefer over air travel.

2. Artificially increase the price through taxation.

3. Artificially decrease supply through regulation.

There’s nothing on the horizon for option 1, and since we live in a democracy, democratic mechanisms are the only means you have for 2 or 3, unless you wanted to resort to something like terrorism.

Your presupposition that we can’t have cheap air travel while avoiding catastrophic man-made climate change is in no way obviously true, and your suggested solution is a utopian fantasy.

Your argument presupposes that we let the free market run its course, but it's widely agreed that co2 emission controls will have to involve regulation or market steeting such as emissions trading.

Putting aside for a moment the fact that the most significant reductions in emissions have been generated by free market activity. You haven’t proposed gentle market steering and incentive creation, you quite literally suggested the “phasing out” of air travel.

> the most significant reductions in emissions have been generated by free market activity

Not sure what you mean, globally there are no reductions in emissions. And you would have to phase out a lot more than just air travel. Personal cars too and overall reduce consumption like ten fold or more, basically destroy this whole capitalism-driven consumerist way of life.

That’s only true if you pretend growth isn’t occurring. Every Mwh of renewable energy consumed is one less Mwh oh fossile fuels that would have been burned, and the market is producing more and more of those every year.

This anti-capitalism stuff seems completely irrelevant too. Every economy is based on consumption, even socialist ones. The only reason the USSR didn’t have as many car owners as the USA is because their economy was in a permanent state of crisis. Market forces don’t go away when you implement socialism.

There is growth in emissions globally. Because forced consumption of non-economical renewable energy doesn't actually work due to the same market forces you speak about. It just makes some rich people richer and others poorer. Resulting in more demand for cheaper products and services that subsequently create more demand for cheaper energy from places where there is no forced consumption of non-economical renewable energy.

> Every economy is based on consumption

I'm talking about buying a tesla level of consumerism, that's not everyone in every economy, but relatively few and they are part of the problem, not part of the solution.

Some markets are viable - even well suited - for electrically propelled planes.

Norway is sparsely populated and it has been a strategy for decades to have small airports everywhere out in the boonies.

Most flights are operated by twin-engined turboprops seating 20-80 passengers, in part doing short flights between islands in the north - an excellent use case for electrical planes.

The big question is whether one can recharge them fast enough - by swapping battery packs if need be. No airline is interested in replacing 50 turboprops with 100 electro planes to serve the same routes.

Another big problem is landing weight limits which are lower than takeoff limits.

Not for long haul jet flights anyway.

It could significantly impact the prices of the electric cars by giving same range in half the batteries.

Reduced weight will also help in increase in speed.

We have no idea how much it will cost. The same range in half the batteries might not save any money. And while performance would improve a bit, the main limiter right now in electric cars is price, not weight.

Totally agree on the price point.

But, the study mentions unused lithium trapped in the battery, so if a solution if found to make that useful, the only costs increase would be to recover the R&D costs.

If any new new chemistry is used to solve the problem with very expensive elements, it could be a problem, but I don't think the scientists will stop at it if they find an expensive solution.

I wonder if you can make them 1D, so you have cells comprised of channels with a lithium whisker at either end, then you shuttle ions up the channel in between the whiskers and they can't get lost.

Why does the anode make such a difference? I always picture it as a little thing at the top of the battery. Does it actually make up a large part of the batteries mass?

Isn’t the electrolyte where the energy is actually stored?

The cathode and anode of a battery are not just the little metal terminals; they are the sites where the electrochemical reaction takes place, and where the energy is stored. Even in an old-fashioned alkaline battery, they run the entire length of the cell: https://en.wikipedia.org/wiki/Alkaline_battery#Chemistry

(For one thing, the surface area of contact between the electrodes and electrolyte is a limiting factor for how fast the reaction can proceed, and therefore how much current the battery can produce.)

In a lithium-ion battery, the cathode and anode are typically constructed out of many stacked layers, separated only by a very thin layer of electrolyte.

This serves as a follow up to India's discovery of a an Iron Ion battery that is literally cheaper than lithium and lasts longer...

Not even sure how its a "follow up" as it has nothing to do with the Iron-Ion battery. Lithium is lighter & more energy dense and will take more chance.

I think where you're coming from is likely something like this Lithium battery steals the press thunder from the Iron ion battery. It's likely the Lithium battery will be used in portable, vehicle applications and if it actually has any benefit the Iron would could be used to store surplus electricity for the grid.

No it doesn’t sorry. The India battery only survives 150 cycles and the iron batteries are heavier than lithium.

You can say the same about various miracle drugs before they under go trials.

Iron might be the future for some energy storage applications (e.g. home batteries) but can't compete for other applications (e.g. Automotive).

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