Hacker News

points by rootusrootus 1 day ago | 0 comments

I want to have viable replacements for all the old school lithium ion battery packs so that I won't wonder when the day will come that one of the many we have will experience thermal runaway while nobody is around to deal with it. IMO a world where we no longer worry about spontaneous battery fires can't happen soon enough.

[–] numpad0 1 day ago

Battery voltages are dependent on chemistry, or, standard electrode potentials of metals used. It can't be configured like way past fractions of volts. And Li has about the highest potential among metals, which is kind of the point of using Li. Which means straight swapping NMC cells with any substitute will cause overcharging. Maybe there are cell configurations that could work in series packs, but it can't be simple swap-ins.

[–] unrented7977 18 hours ago

You can have an interposer charge controller. It isn't complicated. Many/most cells in consumer products already have one.

[–] ricardobeat 1 day ago

Standard sodium batteries are much more explosive than LiFE

[–] nine_k 1 day ago

Can they experience a thermal runaway? Can it be triggered by minor deformations or dents?

[–] margalabargala 10 hours ago

Yes and no, respectively.

Deformations and dents do not trigger a thermal runaway in sodium batteries.

A sodium battery is MUCH MORE likely to experience a spontaneous thermal runaway due to being at a high SOC.

[–] ricardobeat 1 day ago

https://youtu.be/W1ya_ls1zkA?t=209

CATL has demonstrated much better safety for their sodium EV batteries, but home and energy storage packs are more likely to be made of standard 18650 cells like the one in the video.

[–] scheme271 1 day ago

LFP batteries are quite a bit safer than the LMN or NMC batteries. The sodium batteries are more stable than LFP I think but I'm not sure how much longer and if that matters too much for home battery usage.

[–] marcosdumay 1 day ago

There will probably never be a battery that can power your home but can be used without any kind of worry.

The right thing is to place the battery in a way that you don't have to worry abut the fire, not to expect a high-density battery to be perfectly safe.

[–] audunw 1 day ago

Battery safety has very little to do with energy density. High energy density can make the outcomes worse for an unsafe battery, but doesn’t tell you anything about the risk of the fire to begin with.

The reason current Li-ion batteries are unsafe is that they contain a flammable electrolyte. There are batteries with higher energy density that have solid or semi-solid electrolytes. They’re so safe you should probably worry a lot more about driving your car than charging your battery.

Worrying about LFP or So-ion is probably also a waste of time.

[–] cowlevel 1 day ago

LFP batteries are pretty safe. Look up some videos of demonstrations. You can cut them in half with a metal knife and nothing happens besides the loss of capacity, and I suppose the knife heats up from the short-circuit current as well.

I don't know what kind of chemistry shenanigans are going on to make that happen, but it's impressive.

[–] adrianN 1 day ago

A tank of diesel and a generator are a kind of battery that you have to worry about very little.

[–] marcosdumay 13 hours ago

Are you seriously claiming that fuel depots bring no dire risks? Really?

[–] kasabali 11 hours ago

Diesel is damn hard to set on fire

[–] otherme123 1 day ago

They are kind of difficult to recharge using solar panels. They also smell bad and are noisy.

[–] adrianN 23 hours ago

Of course, but that was not the point. Evidently there are ways to store energy that are quite safe, so you can't conclude that all forms of storage are inherently unsafe.

[–] qwytw 14 hours ago

Well diesel can catch fire in certain circumstances and can do a huge amount of damage when it does. I'm not sure it's that much safer than some types of batteries...

[–] Brian_K_White 1 day ago

inherently self-limiting processes are nothing rare or special