Batteries with 50 per cent more energy with pure silicon anode

https://www.ecn.nl/news/item/batteries-with-50-per-cent-more-energy-one-step-closer/

by Gravityloss • 9 years ago

135 75 9 years ago

zeristor• 9 years ago

There is a recurrent pite patter of amazing new battery technologies, but of course the question is it can it be mass produced.

Are there any good websites to gauge battery development progress as opposed to the vital, but often ephemeral research progress.

Gravityloss2• 9 years ago

I was trying to create some kind of categorization prototype on google spreadsheets but it's a bit hard to squeeze out comparable metrics.

Cost, Reliability, Capacity

You could list cost of materials, number of cycles with 80 percent capacity left, capacity in Wh/kg.

But it would still be incomplete. Maybe some "driving cycle" style standardized tests for various uses. Also manufacturing scenarios.

Hard to create something non gameable.

DennisP2• 9 years ago

The article addresses that:

"These discoveries usually concern materials that can only be produced in a laboratory environment on a very small scale. What makes our invention so promising is that the technology for mass production of this material is already within reach due to its similarity to an existing production process for solar cells."

jandrese2• 9 years ago

I have to admit I'm a bit concerned about the amount of cost savings that can be realized by building it with the same methods as solar cells. Even with the precipitous drop in solar cell prices over the past few years they still aren't cheap.

hwillis19• 9 years ago

They steadily make their way into the mainstream. Silicon has been used in batteries for several years now, in low amounts. Usually the new "big news" comes with a significant gotcha. For silicon this has always been the cycle life. Silicon hasn't seen larger use because it expands by 400% when filled, compared to graphite's ~12% expansion. This though- this is very cool. If they've actually demonstrated 100 cycles in a pouch cell, made with reel-to-reel, that may mean that commercial cells are <5 years away.

Commercial cells have 500-800 cycles in their lifetime (until their capacity falls to 80%) and are universally made on reel-to-reel machines. There are a ton of difficulties moving from a coin cell to a prismatic/pouch cell to a cylindrical cell, but I can't understate how encouraging it is that they got to 100/400 cycles.

Are there any good websites to gauge battery development progress as opposed to the vital, but often ephemeral research progress.

Not that I know of, sorry.

csours3• 9 years ago

What are the critical questions you should ask about battery technology?

Here are some I've thought of, please suggest others:

1. Cost of raw materials - even if the tech improves, will it still be expensive?

2. Charge/Discharge cycle count - thermal and mechanical stresses

3. Power to weight ratio; power to cost ratio

4. Manufacturability - does it require novel manufacturing techniques or can it be integrated into an existing product line

5. Round trip energy losses

6. Safety

Gravityloss2• 9 years ago

http://www.greencarcongress.com/2017/10/20171031-ecn.html

Green Car Congress provides good context. This is also a potential manufacturing revolution.

But it's a hard problem because of the massive swelling of silicon during the lithiation, I think during discharge.

vorotato• 9 years ago

<joke> Oh, Solution. Phones with stretchy backs and a balloon battery. </joke>

juliesulti• 9 years ago

You laugh, but a pouch cell as mentioned in this article is in fact a cell that is permitted to swell and shrink. That's probably why these researchers started there.

As regards the article, Lithium-Silicon batteries have the potential to add much more than 50% to the charge density of Lithium-ion batteries. More like 400% in theory. But nobody has demonstrated a cheap, production-ready process for such a thing, because a charged silicon anode occupies much more space than a discharged one, and the associated mechanical stress is a severe problem. There has been an endless parade of press releases from universities and national laboratories over the past 10 years on this topic.

hwillis19• 9 years ago

Silicon has been used in batteries for several years now in low amounts. It hasn't seen larger use because it expands by 400% when filled, compared to graphite's ~12% expansion. Most attempts to solve this have been extremely complicated; nanopatterning, nanowires, graphene coatings to literally compress the silicon metal, etc. It's one of the most promising avenues for battery tech (silicon anodes alone may be able to increase overall energy density by 2-3x), but it's been a very difficult problem to nail down. Nobody has been able to get the trifecta of performant, long-lasting and cheap.

This though- this is very cool. If they've actually demonstrated 100 cycles in a pouch cell, made with reel-to-reel, that may mean that commercial cells are <5 years away. More likely 10+ years, as there are any number of things that could shut this down and the tech may not be compatible with cylindrical cells. Regardless, this is one of the most promising sounding press releases I've read in a long time. PVD anodes will be expensive (this is similar to the process to make mylar), but may be comparable to current processes, which require a long, temperamental and expensive solvent + drying process. PVD could even make this process more reliable (fewer failures) and consistent.

Commercial cells have 500-800 cycles in their lifetime (until their capacity falls to 80%) and are universally made on reel-to-reel machines. If it can't be done on reel-to-real it can't be done cheaply. There are a ton of difficulties moving from a coin cell to a prismatic/pouch cell to a cylindrical cell, but I can't understate how encouraging it is that they got to 100/400 cycles. It's near unheard-of with fully silicon anodes.

This is also quite promising for future development. When they say 1000-2000 mAh/g they're referring to the anode itself- only the weight of silicon, not the full battery. Silicon tops out near 4000 mAh/g, so there's a reasonable headroom there. 50% increase in overall capacity for the entire battery is fairly conservative. I presume it's because they can only apply very thin layers of anode silicon. That may mean there's a lot of room for growth though! They just have to thicken up that layer.

I'm still very skeptical of their long term capacity though. The problem with anodes like this is the nanoscale features. You basically have a huge tangle of velcro: that's done to increase the surface area exposed to the electrolyte, which solves the anode expansion problem. The drawback is that when that surface area becomes restricted, and it inevitably does, the SEI affects the distribution of li ions inside the silicon, increasing damage. They do appear to have found a way around that, but it may still put a long term limit on capacity. The thicker you try to make the anode (to increase energy density), the deeper the "velcro" becomes, and the more the SEI blocks lithium. It may also make these batteries more sensitive to heat and overcurrent and over/undervoltage- anything that disturbs the SEI may cause dramatic irreversible effects.

Random related fun fact: Silicon requires the use of copper rather than aluminum foils in batteries. Aluminum is a semiconductor dopant (the exact one used in your computer, in fact), and if you deposit silicon onto an aluminum foil it will form a very weak diode that causes a ton of problems. In computers an extremely thin silicon oxide film is used between aluminum wires and the transistors they connect. That layer is extremely resistive and causes a bunch of headaches, but way smaller ones than tiny diodes would!

baldfat• 9 years ago

that commercial cells are <5 years away. More likely 10+ years

That has been the conclusion of hundreds of these battery technology stories. We still haven't seen one these to work out yet in the past 20 years.

hwillis19• 9 years ago

I assure you, they do regularly. A123 is the most well known example, but the vast majority of new developments don't involve a new company being formed. Making batteries is hard and few researchers want to build companies. Instead these developments quietly slip into commercial formulations as continuous, incremental improvements.

There's certainly an unending flood of hyped up articles about new experiments, but all of those have some kind of caveat that's glossed over. Cost, manufacturability, or performance. One is always missing. They're usually pop articles or university releases that misunderstand, misquote and play up the papers involved.

This is a release from a private company that hits all three of the important targets. Those are pretty reliable, normally. Flow batteries are an exception, but that's because the professor behind that is way overenthusiastic about them and needs large-scale funding. He's kind of notorious for overpromising; I remember a story by a student under him who used his calculations to derive the scale at which flow batteries became economical and found it was an order of magnitude bigger than a power plant. The professor himself had set up those equations but never actually done them to figure out how big the battery needed to be.

Leydenjar comes off as very conservative in this release. They're announcing an insane improvement, literally decades ahead of when it was expected. Most people would have announced this in coin cells but they waited until they had developed a mass production machine and tested it, and they seem to have replicated those results. Even if this costs 3x more than normal batteries there will be huge demand for it. The battery in an iphone costs $3. Apple wouldn't even blink if a 50% better battery cost $60.

These guys are saying that they pretty much have a product already. Pouch cells make up the majority of batteries that aren't in laptops, teslas or power tools. They've got a manufacturing machine BUILT already and appear to expect a high cycle life. I'm pretty inclined to believe them if they say they can make these affordably.

olivermarks• 9 years ago

Thank you for such an informative post

csours3• 9 years ago

Commercial cells have 500-800 cycles in their lifetime (until their capacity falls to 80%)

What does this mean? I feel like I charge my phone more than 500-800 times.

phinnaeus• 9 years ago

Once a day for ~two years, and then the capacity is at 80% of original. Seems pretty accurate to me.

hwillis19• 9 years ago

Under standard test conditions. That means 100% depth of rated discharge at a set speed (between 1 and .1 C, ie fully charged/discharged in 1-10 hours) and temperature.

Cycle life increases dramatically at lower depth of discharge, so if you normally recharge your phone when it gets to 10% it'll last twice as many cycles. High temperature and fast discharges will reduce that.

Essentially your phone is rated to be driven to 0% once a day for ~2 years, give or take a bit. Less if it gets hot, which it will, because the battery is used as a heatsink for the rest of the phone.

woodandsteel3• 9 years ago

Could you explain what a pouch cell is? Is it the same as the battery in a cell phone or laptop? Why does it matter for this development that it's a pouch cell rather than some other type?

hwillis19• 9 years ago

Cell phones use pouch batteries, aka prismatic cells. Laptops almost all use 18650 cells, which are cylindrical and look a lot like very large AA batteries.

Coin cells are just really simple. They're pretty standard for proving your battery works. The thing is that there is a huge difference between that and a real useful battery. You can pay a grad student overtime to build a coin cell of about anything. You need a machine to make a pouch cell.

It's like if someone showed you a go-kart and said they could make a car. They share the same elements and everything, but there's a definite world of difference between them. It's a lot more than just being bigger.

kpennell• 9 years ago

thx for weighing in all over this thread

tmaly2• 9 years ago

Does this still need lithium?

hwillis19• 9 years ago

Of course. Lithium is the third lightest element and nearly the most electronegative (ie it has a high voltage). It's the best battery material you could possibly pick! Not to mention, it's absurdly cheap and incredibly common. Lithium makes up <1% of the cost of a battery.

davesque2• 9 years ago

Is it really that common? I was under the impression that it's somewhat scarce and, furthermore, a large amount of Lithium deposits reside in regions of relative political instability:

https://www.economist.com/blogs/graphicdetail/2017/06/daily-...

Bud• 9 years ago

This article, and this comment thread, both seem to be ignoring what is actually in the way of any "50% more energy" battery tech being used in consumer laptops: FAA regulations limit all such batteries to 100 watt/hrs or less. It's not Apple, it's not Samsung...they have no choice.

So until we get over our stupid post-9/11 policies, it doesn't matter if Star Trek batteries magically spring into existence. The tech isn't going anywhere, other than allowing something like Apple Watch to have a little more capacity.

rconti• 9 years ago

That's fine. Laptops can keep getting more efficient. This tech can be used for cars and home storage and.. basically everything except devices like laptops that are on that 100w/h boundary. Already, laptops suffice for most flights. Then, eventually, this regulation will go away.

Nition• 9 years ago

Have a high-capacity laptop battery for normal use and a cheap, lower capacity 100Wh one you can swap in to take on flights.

jpm_sd• 9 years ago

Those rules have nothing to do with 9/11, they are based on risk of fire due to manufacturing defects.

mitchty2• 9 years ago

That and limiting the amount of energy that could be released if there is a defect.

I don't think i'd want a 1Kwh battery on a plane.

praseodym• 9 years ago

The 2017 15” MacBook Pro only has a 76 Wh battery, so this is mainly a design choice by Apple (smaller battery means smaller laptop) and not due to FAA regulations.

Source: https://www.apple.com/macbook-pro/specs/

Ajedi32• 9 years ago

And that's a laptop. Watch and phone batteries store far less energy than that. Even the most power-hungry phone would certainly be able to take full advantage of a battery with an additional 50% capacity.

Johnny555• 9 years ago

I already get 6 - 8 hours of lifetime out of my laptop, I don't really need 50% more battery (saving a few ounces or cubic centimeters wouldn't make much difference to me either). I can use the power outlet on the plane if I'm on a flight longer than that.

However, I would love 50% more battery lifetime in my phone without adding more weight or volume.

Or 50% more range in an electric car (or reducing the size/weight/cost of the battery pack).

There are lots of applications for batteries that don't involve taking large batteries on the plane.

ChuckMcM• 9 years ago

Sorry but I have to disagree. While the limit is important for appliance electronics like laptops it doesn't have any impact at all on electric vehicles which are all mostly LiOn powered. 50% more range or 50% less weight would be an interesting change to put in the mix at Tesla for example.

If you look at where batteries are going to be in volume in the next 20 years it will be in grid storage, off-grid house energy storage, vehicles, and potentially small industrial tools.

Of course if this particular breakthrough actually makes it into batteries we will all be pleasantly surprised, as battery "breakthroughs" have a success rate quite a bit lower than 'venture funded startups' :-)

btilly• 9 years ago

If you can store 3/2 times as much with the same battery, you get the same with 2/3 as much battery.

So that should be 50% more range or 33% less weight. Not 50% less weight.

Dylan16807• 9 years ago

You can have multiple batteries. I think.

But I've never had a laptop with a full 100 watt hours anyway, and even more important is my phone where that restriction is miles away.

dzhiurgis3• 9 years ago

Does moving on silicon reduce the need for nickel/cobalt?

hwillis19• 9 years ago

No, it shouldn't. There's the anode and the cathode- anodes are invariably graphite currently, and cathodes are where the cobalt is (if there is cobalt).

This is about entirely replacing the anode graphite with silicon.

googletazer2• 9 years ago

Very thought provoking read. Speaking of batteries does anybody know what's happening with LiFePO4?

hwillis19• 9 years ago

As far as I know, not too much. It's got pretty bad energy density and nowadays it's very common to just skip it entirely. It's real claim to fame is safety- it's not any cheaper despite the materials (half the cost per kg * half the capacity per kg = the same cost), and I haven't heard much about improving the performance.

Meanwhile other chemistries have shown much greater improvements in safety, energy and power, and price is understood to be more about the scale than the chemistry.

googletazer2• 9 years ago

thank you

Batteries with 50 per cent more energy with pure silicon anode

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