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Comment by longstation | Hacker News Reader

I happened to read the same information but reported by another publisher [1]. In that article, it points out that the energy density is only 60% of a traditional lithium-ion cell, but that disadvantage is offset by not having to use much cooling device like the lithium-ion ones.

The same information is represented pretty differently in this article, leading people to believe the energy density is better:

"The new battery cells are claimed to deliver far more energy density than current lithium-ion batteries, without the cooling, heating or rare-earth problems they face."

Still, I think is an encouraging news and I really love, just not quite a fan of the way they present it.

[1] - https://newatlas.com/energy/gmg-graphene-aluminium-ion-batte...

[edited for grammar]

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You could easily imagine an EV with a hybrid battery pack consisting of 2/3 Li-Ion and 1/3 Al-Ion. You pay very little in range for the combination compared to a Li_Ion pack, but you gain flexibility. You then discharge the Al-Ion part of the pack first, partly because it has better longevity across cycles, but mostly because this then lets you charge that empty third of the pack very quickly giving enough range for an extra hour or two of driving.

Delivering that much power seems pretty difficult to me. EVs already charge at dozens of kW. How high do you have to make the voltages to keep the cables a reasonable diameter when you want to charge in the Megawatt range?

If you assume that 500A is the largest cable that a user can handle[0], then 2kV per megawatt. If you don't mind actively cooling the part of the cable the user handles, then you could run at higher currents for the same cable size.

The biggest problem likely will be the much higher demand charges from the power company (they really don't like sudden large loads), so the charging station will likely need a large battery pack of its own.

[0]: You want injured/elderly people to be able to charge without assistance so cable weight/stiffness is a important design factor.

Sounds crappy but what if faster charging ends up being accomplished with more cords and more charging ports? Want double charging rate? Plug in two cords.

I can see this as something that is included in upgraded trims. Mid-level trim = two charging ports. Premium trim = 3! $$$

You could definitely increase the ampacity if each charging cord was only one wire. Perhaps that's the key to quick recharges?

Also gives you something to do, while you are waiting. By the time you plugged in the 5th wire, the first 4 charged you halfway :D

A "Megawatt Charging System" (MCS) is already in development for charging heavy commercial vehicles and aircraft. It's designed to scale up to 3000 A at 1500 V.

https://en.wikipedia.org/wiki/Megawatt_Charging_System

They're already working on deploying 350kW 500 amp charging stations. That's about 5 minutes to get 100 miles, and the cables are a bit awkward but not too bad. And 500kW 500 amp is easily accomplished on the same standards.

Also keep an eye on potential 2-3 megawatt plugs for trucks.

I've always thought it should go the other way.

Add a supercapacitor.

This would allow bursts of extreme power, along with stronger regenerative braking with full capture of energy.

I think the racetrack would be a great use case.

Last I looked, supercapacitors just aren't quite high up enough on the volume/energy curve.

Getting rid of a few batteries to make space for a few supercaps so you can regen quickly when emergency stopping sounds great, but then you realise it can only capture a tiny portion of the cars energy at 70 mph unless you replace nearly all the cars battery.

I wonder if the apparent contradiction can be explained by the difference between the energy density of a cell (i.e. a single instance) vs of a battery (i.e. a practical aggregation of a number of cells)? I don't know how much space the cooling etc. takes up in a practical lithium-ion battery.

In this case, energy density refers to the energy per unit mass, not volume. But your point still applies, for application in a vehicle you need to compare the mass of the complete battery systems, not just the cells in isolation.

As battery designs are getting better, the difference is getting smaller and smaller.

Turns out cooling systems can have very thin tubes with very thin walls.

That article was discussed a bit here:

Superfast-charging aluminum-ion batteries outpower lithium-ion - https://news.ycombinator.com/item?id=27205855 - May 2021 (8 comments)

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