Hacker News new | ask | show | jobs
by tylerrobinson 600 days ago
> And EV batteries turn out to be very recyclable.

Can someone explain what it is that makes batteries wear out to begin with, and what has to be added back to make them work again after they’re shredded into “black mass”?

2 comments

> Can someone explain what it is that makes batteries wear out to begin with.

For lithium ion batteries, effectively what happens is little crystals start forming which cut down on total usable surface area and in the worst case short out the cell. If you've ever seen copper plating using electrolysis, effectively that is happening in the battery. The charge and discharge cycle end up pulling over materials between the cathode and anode which aren't desirable.

> them work again after they’re shredded into “black mass”?

The process of separating the component parts is something we do anyways with virgin materials. It's mostly just chemical reactions to remove desired elements and compounds and then reform them into a workable byproduct.

But what should also be stated is that by weight, batteries are mostly metal. It's a metal foil coated in a thin layer lithium goo. Even if we simply ignored the lithium goo, most of the metal could be recycled by simple melting down the metal foil and jacket.

The goo has valuable elements which is why there's effort to recycle it.

They work by controlling a reversible chemical reaction. This control is done by keeping various things separated. To some approximation, they wear out because the stuff doesn't stay separated, it starts to mix, and starts to break down into other chemicals or whatever (and thus isn't available for the intended reversible reaction).
Some neat details , including some cool pictures.

[https://faraday.ac.uk/wp-content/uploads/2021/04/Faraday_Ins...]