[HN Gopher] New capacitor with 19-times energy density
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New capacitor with 19-times energy density
Author : tromp
Score : 81 points
Date : 2024-05-08 15:33 UTC (1 days ago)
(HTM) web link (www.livescience.com)
(TXT) w3m dump (www.livescience.com)
| kube-system wrote:
| > 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?
| atoav wrote:
| 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 wrote:
| 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.
| LorenPechtel wrote:
| Makes me wonder if there might be a viable hybrid with no
| battery, just a supercapacitor. It wouldn't allow you to
| reclaim energy off hills or the like, but give the
| advantage hybrids have in city driving without the downside
| of that battery pack that will wear out in time.
| adrianN wrote:
| Some diesel busses have a bank of capacitors that is
| charged when braking that can then run the onboard
| electricity for a while.
| CyberDildonics wrote:
| 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.
| ComputerGuru wrote:
| > the limitation is in the amount of power that can be
| pumped into them
|
| You could say that. You could also be more pedantic and say
| that this comes at the cost of _some_ decrease in battery
| life (and efficiency) due to the resistance resulting in
| some amount of heat in order to facilitate this high-speed
| charging process.
|
| But I don't know if the ROI on improved battery life would
| be worth the complexity, size, weight, and cost of a two-
| stage charging process. As battery tech improves, that
| resistance continues to come down.
| CyberDildonics wrote:
| _this comes at the cost of some decrease in battery life_
|
| What does? I said the limitation is usually getting
| enough electricity to charge them fast. Most of the time
| EVs are not being charged as fast as they could be.
| datameta wrote:
| 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 wrote:
| 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.
| datameta wrote:
| Indeed, DRAM and Flash have experienced a convergence - in
| server and mainframe land there is storage-class memory
| that functions as a cache or LUT between DRAM and Flash.
|
| I believe we are a bit farther from a true hybrid
| capacitor. As for true hybrid memory I believe the
| likeliest solution for embedded applications will be one of
| the different analog in-memory compute techniques currently
| being iterated on.
| NullifyNAN wrote:
| Yes because ultimately the goal of capacitor research is to
| make it more similar to a battery in terms of storage.
| neuralRiot wrote:
| And battery research goal is to make them behave more
| capacitor-like, eventually they will cross their paths.
| CyberDildonics wrote:
| _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-system wrote:
| 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 wrote:
| 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.
| ortusdux wrote:
| 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 wrote:
| 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
| ortusdux wrote:
| Great link! It looks like the caps he used were ~ 3 J/cm3,
| so 1/65th the density of the ones in the article.
| nick238 wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| m463 wrote:
| 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.
| atoav wrote:
| 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 wrote:
| 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.
| tomxor wrote:
| > 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.
| ComputerGuru wrote:
| > 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.
| lazide wrote:
| It also has plenty of plain old basic chemistry examples
| showing it false - lithium ion vs lead acid, gasoline vs
| fuel oil, etc.
| tomxor wrote:
| Yes, it's only a high level observation, but one that seems
| to hold true for electrical storage so far, i.e where there
| is a closed system with an electrical input and output.
|
| For fusion there are also various direct energy conversion
| methods for electrical output, but not the reverse, i.e i
| don't think there is method for nucleosynthesis directly
| from charged particles.
|
| In a more general sense, sure, power vs energy relation
| doesn't hold, but when limiting the system to the
| requirements to be a self contained electrical storage
| component, this relationship seems to emerge.
| sfink wrote:
| 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 wrote:
| The "magic smoke" is what happens when your PC gains a
| scintilla of self-awareness and realizes it entered your home
| without an invitation.
| swayvil wrote:
| There's a scifi movie. 5 million years to earth. They do
| something like that.
|
| It's a good movie.
| cooper_ganglia wrote:
| 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 wrote:
| 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.
| mk67 wrote:
| I thought sunlight and water also kills them.
| LorenPechtel wrote:
| 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 wrote:
| Could be useful for Mach effect thrusters. More transient mass to
| push against.
| swayvil wrote:
| Advertisement density is pretty maxed out on that site
| Animats wrote:
| 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 wrote:
| 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 wrote:
| Another Better Battery Bulletin. Meh (An exCeptional capacitor
| circular?)
| queuebert wrote:
| 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 wrote:
| 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.
| LorenPechtel wrote:
| 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.
| queuebert wrote:
| In fact the books use that rapid discharge property to power
| weapons.
| ranger_danger wrote:
| > 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)?
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