Li -ion battery


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Murphy's friend

Regular Member

Joined: 04/10/2019
Location: Australia
Posts: 96
Posted: 09:38am 06 Mar 2021      

Hi Bruce,
While I have not taken apart my new Li-ion battery pack cells I did open a shortened LYP cell (200Ah). I assume the Li-ion type is similar with different chemical inside.

Basically its constructed like a very large capacitor (and I understand it works in a similar way, eg. no chemical reaction in an electrolyte).

There are two different, very thin, foil type 'plates', one is aluminium and the other copper. These are coated with the special 'stuff' and are separated by a very thin plastic sheet.

The plates are each connected to its terminal on the top, I think there were nearly one hundred 'plates' of each variety. There are no wires inside unless the cell has an inbuilt balancer.

The 'plates' are only as big as the cell outline but the plastic separator zig zags between the alternating 'plates' and is many many meters long.

There was no liquid  inside the cell I opened but the plastic separator sheet felt wet and smelt funny. It also started to smoke when I bundled it into the rubbish bin, I guess it reacted with oxygen in the air. Threw it  on the lawn until it had dried out.

If you want a better explanation how it works just google it, there are some very good texts on this subject.

My new Li-ion cells are tightly strapped into 4 cell packs with aluminium endplates to prevent bulging.
The LYP cells require one to come up with one's own strapping method and, if not done very well, will swell in the middle too.