From what I’ve read, Li-ion cells / batteries over time can develop internal threads or filaments (also known as “dendrites” I believe, as with neuro-cells).

Evidently, these microscopic, branch-like structures “grow from the anode toward the cathode during charging, potentially penetrating the separator and causing internal short circuits, fire risks, or premature battery failure.” –Argonne National Library and scads of [other links](lithium-ion batteries develop dendrites when charging)

Me, on the one hand I’m typically all-thumbs upon power cell chemistry, but OTOH don’t want to burn my place down accidentally. At the moment, I’ve taken to removing most of my collection of lithium-ion cells (apart from my cellphone battery), and placing them in lined, steel pans. Also, when I charge my cellphone these days, I put it in a steel pan, like in the OP. Just to be sure, you know?

Now, do I think that the risk of such Li-ion “dendrites” in cells escaping their outer, protective casing is high? Absolutely not, under normal conditions. (altho that also comes down to quality of the battery, which might be quite sketchy, depending) Meanwhile, do I think that such a potential fire might be disastrous? You betch your bippy I do! (just look at poorly-made ebike batteries for some examples)

So I’m thinking that both old Li-ion cells and ones which are frequently recharged (as with cellphone batteries), are at a higher-level of risk, FWIW.

Got an opinion on all this…?

  • ChaoticNeutralCzech@feddit.orgEnglish
    4·
    1 个月前

    I store sus cells inside a glass jar inside an old metal can with sand in between. Not very convenient for charging though… Some people use no sand but two metal cans, with a stone/piece of brick between their bottoms for some heat insulation. This is easier to pull cells out of (no sand spill if tilted) but their terminals need to be taped over to prevent contact with the sides.

    But yes, the last time I had to pierce a cell I did it on an old tray like this (it was too bloated to disassemble the powerbank whose circuitry I wanted to reuse; it’s relatively safe to pierce the outer pouch and not the internal structure (!), obviously then it needs to be disposed of either way − just think how much pressure was needed to bend the milled aluminum like this)

    I usually only charge sus cells when I’m in the room but there’s plenty of dirty old heat-resistant containers in the tool shed so I could leave it in one for overnight charging. With enough thickness and surface area, like the tray you showed, it will likely distribute the heat of a single 18650’s thermal runaway without the other side getting hot enough to ignite what’s underneath (I put it on bricks to be safe, and cover it too, the gas pressure inside a cell releases lots of kinetic energy if it bursts). Glass jars aren’t conductive and withstand lots of heat but might break in an explosion, which is why I add another layer; a glass jar on a tray should be enough for charging a single cell, at least that’s what I did last time.