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Comment by cmrdporcupine | Hacker News Reader

I live rural and I'm hoping the next decade will bring a wave of cheaper safer sodium ion battery options. Something I'd feel a lot more comfortable with putting in or around my home since they don't have thermal runaway issues, their materials are theoretically cheaper, and they can withstand colder temperatures.

While I'd like to use my EV as backup, the cost and integration issues right now are just not sensible. The utilities and manufacturers have made it too cost prohibitive.

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LiFePO4 are much more robust against thermal runaway, omit a lot of the expensive materials that are in typical Li-NMC batteries, and have a better cycle life. They still can't be charged below 0°C, they have worse specific energy, and they generally can't handle the same peak power output, but they're a better choice for fixed storage applications IMO.

GP is referring to sodium ion batteries. They’re even cheaper materials wise (no lithium) and have even more favorable outcomes for freezing conditions.

Worse energy density and similar or potentially worse number of cycles, but that’s being worked on.

But an important difference is that LFP is available today. Expecting a dramatic shift to sodium ion anytime soon is wishful thinking. Battery tech evolves steadily but slowly.

CATL is already producing sodium ion at competitive prices. Expect 5-10 years to end up with a flood of stationary battery products based on them, at prices less than LFP.

Do you have a link to a good brief on these from an engineering point of view? Where can I buy cells, in what packaging, with what specific energy & power, peak draw, charge rate, etc etc? I do some tinkering around with batteries for various purposes and I'd love to learn more.

There's numerous sodium ion batteries in 21700 packages you can buy online. They have specs and ratings, although they seem conservative generally.

Key difference between them and LFP/Li-Ion is the charge/discharge curves and termination voltage are radically different.

They'd have to beat used car battery pricing and I suspect used car batteries are going to be worth ~ $0 until recycling becomes better.

Apparently, it's almost impossible for wrecker yards to get rid of EV car batteries, even if the battery pack is still fine (but the car was totaled).

That's weird, the reason EVs have been so easy to total is that the residual value of the battery pack is high and therefore it takes less damage to reach the breakeven point than it does with an ICEV.

Also that the dealerships etc are super paranoid about any potential damage to the pack. They'll declare total loss even when there's no evidence of battery pack damage rather than risk liability for being wrong about it.

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