New capacitor with 19-times energy density

https://www.livescience.com/technology/electronics/ev-batteries-could-last-much-longer-thanks-to-new-capacitor-with-19-times-power-density-that-scientists-created-by-mistake

by tromp • 2 years ago

106 58 2 years ago

livescience.com

kube-system2• 2 years ago

we were able to achieve an energy density of 191.7 joules per cubic centimeter

Which is still quite a bit lower than

https://en.wikipedia.org/wiki/Lithium-ion_battery

900–2,490 J/cm3

And I don't see anything here about self-discharge rates, which are a big limitation for using capacitors for energy storage over any period of time. Does anyone know if the full study has that information?

atoav2• 2 years ago

The main use of capacitors in circuits (if we go by capacity) are bypass capacitors. These are essentially small buffers of electricity that can charge and discharge quickly when a jolt of power is needed downstream.

Without bypass capacitors every sudden draw of power would pull the supply voltage of the whole system down, especially if your power source (battery) can't react that quickly or has limited discharge rates.

Without having looked into the plans here, I'd expect a super-capacitor solution to look like this:

1. You charge your cars of super-capacitors super quickly at special charging spots and drive away

2. The stored charge is then partly used for driving, partly used to charge the cars actual battery and partly used to act as a bypass capacitor to smooth out the load for the battery

3. Eventually the capacitors are empty, but you had a short charging process that filled part of your batteries

mlyle• 2 years ago

I don't really think of bulk capacitance as bypass capacitance, but here the role is similar (on longer time scales).

Cars are unlikely to have huge supercapacitors useful for changing the charge much, too. (And there's not much point in moving power stored in a capacitor to be stored in a battery).

The main use of this is to provide short duration power, as you describe. That is, lithium batteries have great energy density but not as great power density or cycle life as capacitors. So a small amount of bulk capacitance can improve battery performance and reduce stresses on the battery.

This is more useful for short range vehicles like plug-in hybrids, because they have smaller packs. Larger vehicle packs tend to have plenty of power available, as a side effect of being designed to store tons of energy.

CyberDildonics3• 2 years ago

If an EVs batteries aren't mostly full, the limitation is in the amount of power that can be pumped into them. There isn't really a reason to charge capacitors directly or in any special way.

Even for high discharge I'm skeptical, lithium titanate batteries are probably much better, their durability and extreme charging and discharge rates make them half way to capacitors already.

crote2• 2 years ago

Bypass capacitors aren't really used to prevent a whole-system voltage sag - they are there to deal with the effects of high-frequency signal switching.

The traces supplying power aren't theoretical, so they have a nonzero impedance. This means that when there is any change in power demand due to transistors switching, the trace will try to resist this change in supply current. An increased power demand leads to a very local voltage drop, a reduced power demand leads to a very local voltage spike.

Bypass capacitors are placed as close as possible to the individual chips to reduce the impedance between the capacitor and the chip. You even intentionally use smaller capacitors because the bigger ones have a higher impedance.

datameta2• 2 years ago

Does it make sense to compare a capacitor to a battery? It is a bit like comparing SRAM to Flash imo.

I think some of the areas of a car to be potentially improved with this kind of advancement are: regen braking efficiency, size and weight, battery health.

oliwarner• 2 years ago

Does it make sense to compare them as the lines between them blur? Absolutely! That's the best time to compare.

And the same is true for DRAM and flash. There have been several moments in time when the tables have tilted where battery backed RAM PCI cards have made sense, or where sticking persistent Optane chips in high speed DRAM slots has.

NullifyNAN• 2 years ago

Yes because ultimately the goal of capacitor research is to make it more similar to a battery in terms of storage.

CyberDildonics3• 2 years ago

a big limitation for using capacitors for energy storage over any period of time

Who is saying that's the point of this capacitor?

kube-system2• 2 years ago

The first sentence in the article is:

A new material structure could revolutionize energy storage by enabling the capacitors in electric vehicles or devices to store energy for much longer, scientists say.

choilive• 2 years ago

Yep still much lower than Li-ion batteries but within punching distance for sure. I also don't think this is intended to compete with traditional battery tech as much as making it even better in applications where supercapacitors currently excel at.

ortusdux2• 2 years ago

I wonder what the comparison is in J/kg? I could see lithium & capacitor hybrid systems being viable in EVs. The cybertruck's battery housing is full of plenty of deadspace, and if these caps have 1/10th the energy density you could squeeze in an extra 10+kwh of storage. Caps typically have a much longer lifespan, so I could see them acting as a great buffer for the rapid charge/discharge of regen braking.

skykooler• 2 years ago

I recall following a project about 15 years ago where someone converted a car to electric using a lithium battery for range and a bank of ultracapacitors to increase peak power and handle the energy from regen. Here's the page on the project: https://www.metricmind.com/ac_honda/main2.htm

nick238• 2 years ago

The source article is Enhanced Energy Storage [...] Ferroelectric Ceramics via Domain Engineering https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10381779/

It seems like they didn't really look at leakage current, but did apply a 10 Hz sine wave to it for about a day (~1 million charge/discharge cycles) and it didn't degrade notably.

mitthrowaway2• 2 years ago

I don't think the intent is to use the capacitor as a substitute for battery energy storage, but as a complement. I don't think these would be a good fit for EVs, but for supercharger stations maybe? Charge/discharge efficiency and cycle lifetime will probably be higher than a battery, and in stationary applications, cost matters more than weight or volume. Of course cost depends on production volume, which isn't something you can measure in the lab, so who knows.

It might also pair well with battery chemistries that are good for energy density but poor on power density, like lithium-sulfur or LFP.

cogman10• 2 years ago

For an EV, they could be useful in stopping/starting. Rather than having regen go to the battery you could first send it to a capacitor which then trickle charges the battery (reducing wear). And rather than pulling directly from the battery, you could pull from a capacitor first to get to cruising speed. That would allow the battery to slowly discharge into the capacitor rather than going directly into the motor at full force.

You'd play to capacitors high cycle life and fast charging/discharging capabilities rather than their density.

aidenn0• 2 years ago

That's also much less than 19x what an EDLC can store. Picking a standard Maxwell part[1] I calculated 36 J/cm3, so it's more like 5x; still impressive, but comparing a lab result to a product isn't fair; there are EDLCs with much higher energy densities in the lab.

https://maxwell.com/wp-content/uploads/2022/07/3003348.2_3V-...

jcd000• 2 years ago

I can think of many uses for a capacitor with close-to-battery energy density. The cap properties (endurance & high charge / discharge rates) are pretty useful in some applications.

m4632• 2 years ago

I think this would complement batteries.

One big use would be ev road racing.

Cars on a track have high acceleration, followed by extreme braking.

If this energy could be buffered by a large capacitor, the main battery could just be slowly discharged to a capacitor to provide energy for the race. The capacitor would provide and absorb fluctuating energy to speed up and slow down.

I also imagine complex ev battery architecture could be simplified if the energy in and out doesn't have to be radically managed.

I see it somewhat like running an internal combustion engine at one efficient RPM instead of having to run at all RPMs and use a gearbox.

throwaway14356• 2 years ago

that last bit i find interesting. You not just get to run it at efficient rpm it can also be dramatically smaller and have better acceleration. It could even continue to run after reaching the destination (since you have an engine it might as wel do work for you)

atoav2• 2 years ago

More energy density in capacitors is a big thing, as capacitors are easily the biggest parts you will have to use on your PCB (if we exclude non-negotiable parts like connectors, buttons, displays, etc.)

But I'd like to add that it might take a long while for the results of this work getting into market. For circuit designers it is crucial to know under which conditions and after which time capacitors fail (and in which way they fail). This is all knowledge that has to be generated before such a thing goes to market. And usually you don't wanna be the early adopter on things like these

logtempo• 2 years ago

is it a big deal ? Any components need to pass some conformity tests, and testing capacitors is an established process.

There are bike with supercapacitors out there, so it's definitly not that far from the market.

tomxor2• 2 years ago

More energy density in capacitors is a big thing, as capacitors are easily the biggest parts you will have to use on your PCB

I don't think it's that simple, energy density and power density seem to be roughly inversely related across technologies. i.e the more energy you can pack per unit mass the slower it is to get it in and out. A substantially lower power density could actually make the equivalent component larger or heavier for many purposes.

Super capacitors already exist that bridge the gap between electrolytic capacitors and chemical batteries. If you compare the specific energy with the specific power of each the ratio drastically changes from left to right in this table with old electrolytics beating everything when it comes to power:

https://en.wikipedia.org/wiki/Supercapacitor#Comparison_with...

On the other hand this comparison is per unit mass, and these technologies differ vastly in volume density, so a comparison per unit volume would reduce the differences in power density. I'm pretty sure the order for power density will be the same though.

ComputerGuru2• 2 years ago

energy density and power density seem to be roughly inversely related across technologies. i.e the more energy you can pack per unit mass the slower it is to get it in and out.

This sounds really elegant and simple to the point where people might take it as an axiomatic fact but the very existence of both nuclear fission and fusion stops it from being a general rule. They’re both discharging power from individual atoms and it would actually be great if we had a way to slow down the rate of discharge.

crote2• 2 years ago

More energy density in capacitors is a big thing, as capacitors are easily the biggest parts you will have to use on your PCB

Not really. Most modern electronics don't need significant capacitance in F. Your selection of capacitors will be dominated by a very large number of physically small, low-value bypass capacitors, one each placed as close as possible to every single power pin. The main thing you care about is their inductance - which is why you want them small and close to the pin. I'm already using the smallest parts the factory lets me without charging a premium fee, so nothing to gain here.

Beyond that there might be a handful of bulk capacitors distributed among the power rails, but those are rare and already rice-sized. Making those smaller wouldn't hurt, but it's not the first property you'd be selecting it on, and the potential gains are pretty much wasted on anything which isn't an iPhone.

There are still some rather bulky capacitors in things like chargers and power supplies, but those aren't exactly space-limited.

sfink• 2 years ago

Not exactly related to the article, but reading it triggered a sudden realization: vampires are just big capacitors. If you put a stake through their heart, you connect all the plates (possibly many layers of them) and they are vaporized into a cloud of dust.

Well, dust and steam, which could be where the whole "turning into mist" comes from.

I got nuthin' for blood and bats.

CapeTheory• 2 years ago

The "magic smoke" is what happens when your PC gains a scintilla of self-awareness and realizes it entered your home without an invitation.

swayvil2• 2 years ago

There's a scifi movie. 5 million years to earth. They do something like that.

It's a good movie.

cooper_ganglia• 2 years ago

The idea that vampires die when placing a stake through their heart is so funny to me, because most things die once you've put a stake through their heart...

BenjiWiebe• 2 years ago

I think the idea is that vampires don't die unless you put a stake through their heart. Most things have many other ways of killing them.

LorenPechtel3• 2 years ago

But most things die if you put the stake through their brain. Vampires only die if it goes through the heart. I'm thinking of one of Saberhagen's vampire stories where the vampire's car (or perhaps he was a passenger??) has a bomb that goes off, as it goes boom the vampire is worried about whether any of the dash is made of wood.

axblount• 2 years ago

Could be useful for Mach effect thrusters. More transient mass to push against.

swayvil2• 2 years ago

Advertisement density is pretty maxed out on that site

hi-v-rocknroll• 2 years ago

𝄞 Used, abused, without clues 𝄞

𝄞 I refused to blow a fuse 𝄞

𝄞 They even had it on the news 𝄞

𝄞 Don't believe the hype 𝄞

Animats• 2 years ago

This is a ferroelectric capacitor.[1] Those have been around for a while, but in small sizes for memory cells, not big ones for bulk energy storage. Actually, it's just a new material for one, not a whole unit. Here's the actual paper. [2]

The paper makes says it might be useful for pulsed energy systems - radars and such, perhaps. It's a ceramic capacitor, so potentially it can have low equivalent series resistance and you can get the energy out fast. The paper doesn't even mention longer-term energy storage. The picture of a car charging port is deceptive.

[1] https://en.wikipedia.org/wiki/Ferroelectric_capacitor

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10381779/

hinkley• 2 years ago

Regenerative braking is always a big deal in these discussions, put power control circuitry also likes a beefy capacitor. If you look at a Macbook power supply, the size of the caps seems to be dictating the thickness of the brick (the transformer is the same thickness but those can be rearranged)

readthenotes1• 2 years ago

Another Better Battery Bulletin. Meh (An exCeptional capacitor circular?)

queuebert2• 2 years ago

The Rho Agenda sci-fi books rely on capacitors with absurdly high energy densities to power the tech. Is there any thing in the physics that would prevent a capacitor from having a higher energy density than a battery?

TheLoafOfBread• 2 years ago

I remember some attempts to achieve that, do not have source anymore. The whole idea was to take two electrodes and grow thick forest of graphene tubes on them massively increasing surface of electrodes. But to get even close to batteries, electrolyte was necessary, however pouring electrolyte onto electrodes modified in such way caused graphene tubes to break off and create shorts. So ultimately went nowhere. Maybe if it would be possible to grow graphene in the electrolyte directly.

LorenPechtel3• 2 years ago

I would be very, very leery of storing large amounts of energy in supercapacitors. A li-ion battery pack can go into thermal runaway, but a supercapacitor inherently dumps it's energy if penetrated. Electricity moves at a respectable fraction of lightspeed, the energy dump will be *very* fast.

queuebert2• 2 years ago

In fact the books use that rapid discharge property to power weapons.

ranger_danger• 2 years ago

a tiny gap in the core increases the relaxation time — a term used to describe the period over which the capacitor loses charge
materials are layered like pasta sheets in a lasagna

Isn't this similar to how current lithium cells are made? An anode and cathode with a gap layer sandwiched between them (just on a different scale)?

kazinator• 2 years ago

The word "battery" originally referred to a bank of capacitors. One day, capacitors will reclaim the word.

Zababa• 2 years ago

Is "if reproduced at scale" the material science equivalent of "in mice" in biology/medicine? I don't mean this in a cynical "this will never work" way, I'm just wondering about the culture and "path to innovation/mass market" of this field.

New capacitor with 19-times energy density

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