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India Develops the World's First Iron-Ion Battery (energytrend.com)
88 points by doener 49 days ago | hide | past | web | favorite | 27 comments

> it is only capable of 150 cycles of charging and discharging for the time being. At the present stage, the energy density of the battery is also only able to reach around 220 Wh/kilo, which is only around 55-60% of the 350 Wh/kilo of energy density for lithium-ion battery.

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The cycle life isn't too bad given that this is still at the "it works at all" stage, not the "refined to be commercially viable" stage. Remember that 20 years ago the only practical bulk storage battery was lead acid and that had a similar cycle life. We're just spoiled these days with LiIon and LiPoly being so cheaply available.

Also the per-kilogram energy storage is far less important given the price difference between iron and lithium. There's a huge market for stationary battery storage where weight and even (to a lesser extent) size are non-factors compared with cost per kWh.

Lead acid batteries are lousy with a full depth of discharge, but for partial discharges, such as car starter batteries, or solar powered telemetry stations, they can easily have 1000+ cycles of lifetime. If an Iron-ion battery could replace these applications economically, that would be a huge market. Lithium iron-phosphate batteries are great for these purposes, but cost nearly 10x more than lead acid.

When you say "1000+ cycles" do you mean 1000 discharge-a-bit / recharge-a-bit cycles, or an equivalent total energy storage to 1000 full cycles? If the latter, then it's a bit misleading to discuss "cycles". You're actually getting 1000 cycles to 10% depth of discharge, which is equivalent in terms of total stored energy to 100 cycles at 100% depth of discharge.

Anecdotally, when dealing with lead acid batteries, 1 100% discharge is much worse in terms of cycle life than 2 50% discharge cycles or 10 10% cycles. Other chemistries dont have this problem, or are less affected.

This is pretty cool. While lithium isn’t that scarce iron is plentiful. Also would be even nicer if it used fewer heavy metals and rare earth elements.

Lithium is also quite plentiful, not rare at all. It's also not poisonous the way lead or cadmium are.

Lithium batteries are a fire hazard, though, even if we learn to produce them 10x as cheap in the future. Iron batteries are most likely not.

Stationary storage sounds like a killer app. 150 charge cycles doesn't sound like much, but if you're using these in combination with solar power, the batteries could serve for almost half a year.

Yes, for some stationary storage applications 150 cycles would be completely adequate, and would last for many years. Eg: replacement of emergency generators, or some peaking power stations which only operate for a few days per year (we have lots of these in Australia).

The zinc-bromide batteries are doing good work in Australia, aren't they?

They seem to have >5000 complete battery cycles. I think that's the best one can get for stationary applications.

You mean the Redflow ones? They do look interesting, I haven't heard much about them for a while but here's a review from 2016: https://www.solarquotes.com.au/blog/redflows-zinc-bromide-zc...

Ah, it sounds like they went quiet while setting up manufacturing facilities in Thailand and have recently started marketing again: https://redflow.com/redflow-on-growth-trajectory-after-emerg...

>Also the per-kilogram energy storage is far less important given the price difference between iron and lithium. There's a huge market for stationary battery storage where weight and even (to a lesser extent) size are non-factors compared with cost per kWh.

Excuse my ignorance, so what is this Iron-Ion battery good at even if we discount Per Kilogram Storage? Iron / Lithium isn't even the 10% of Battery BOM cost. Am I missing something here?

While true, Iron is much more accessible than Lithium. Which potentially would make it cheaper per pound (eventually). Today that’s not the case, but with time, who knows. Still interesting.

I think the Lithium content makes up about 5% of the cost of a battery from this comment:

"By 2025, the market for mined lithium raw material may be worth $20 billion, compared with $43 billion for refined products and $424 billion for battery cells" in https://www.bloomberg.com/news/articles/2019-07-28/the-lithi...

I noticed in the beginning of the article they claim greater capacity than Li-Ion and then contradict that statement in your quote.

Curious to see how that gets reconciled.

Iron is considerably denser than lithium, so it would have a higher capacity for a given volume.

It's interesting how this tradeoff works. Lighter elements have a higher ratio of electrons to total mass, so they can store more chemical energy per kilogram, but are also less dense so they store less chemical energy per volume.

Of course, chemistry being what it is, it's not that straightforward. Here's a chart of atomic mass and specific gravity against atomic number: http://mrtitanium.com/images/density.gif?lbisphpreq=1

If you look for elements with a high ratio of density to atomic weight, you'll find most of the elements that we typically use in batteries (eg. Lithium, Magnesium, Aluminium, Manganese, Iron, Nickel, Cobalt, Silver).

Edit: Changed 'atomic number' to 'atomic weight' in the last paragraph.

Also metallic iron anode.

I think an issue with alkali ion batteries is you need zeolite electrodes which adds bulk weight. Thus doing a number on your energy to weight ratio.

The 150 cycles is a killer, as is the energy density in certain circumstances, But for something less space conscious like home or commercial energy storage would it matter if it's (I assume) cheaper? Even 150 cycles might be fine for things that discharge very slowly, like a battery in a fire alarm.

They can get better with additional prototypes. They might hit a wall with further development, but they at least think they want.

That's some pretty insane energy density for a prototype vs. years of R&D into a mature technology.

Hope they can improve the charging cycles. Anyone has a clue what the numbers on the matured Lithium-Ion tech is for comparison?

A lot of concern here about the 150 cycle lifetime. But if they could be made cheap enough on a per-MWh basis, they might solve the (IMO) thorniest bit of 100% renewable strategies... seasonal supply balancing.

I've been reading and researching about batteries online for long now. But I haven't come across any group/community that discusses on battery technologies.

Anyone knows of any such slack/discord/Facebook/whatsapp group, then please let me know.

My Materials Engineering thesis (~10 years ago) was on anode technology for Li-Ion batteries I haven't kept up with the field (I work in metallurgy nowadays). I am not sure there would be any online Facebook groups or the like, as with most academic fields I imagine battery research community is still pretty insular.

At the time I found journal articles and conference proceedings were the best resource to keep up with current state of the art.

A few journals I can recommend from memory:

"Journal of Power Sources" "Electrochemica Acta" "Electrochemistry Communications"

Otherwise academics are usually good source you can try emailing professors and/or grad students from local university, they may be willing to give you some pointers.

Here's the link to the publication in ChemComm: https://pubs.rsc.org/en/content/articlelanding/2019/cc/c9cc0...

Fantastic! What's the Voltage of it?

Each new chemistry discovered is another opportunity to evolve to become the next battery technology base, or to service a specific market (consumer or otherwise).

Every battery tech when invented has multiple downsides (e.g. 150 cycles) that then require multiple new innovations to evolve to be competitive.

I wonder how this would compare for Wh/$ vs Lithium batteries?

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