The 104 F (40 C) limit applies somewhat equally
to all Li-ion chemistries. The temperature is
limited because the electrolyte boils just
slightly above that temperature. Same type of
electrolyte in all Li-ion chemistries thus the same limit.
The cell containment vessel can make a
big difference in this temperature limit,
however. Cylindrical cells can often hold
significant pressure while prismatic and pouch
cells can withstand less or perhaps no pressure.
Life a pressure cooker, the higher the pressure
of the electrolyte, the higher temperature you
can withstand. The A123 26650M1 cells (LiFePO4)
would withstand up to 100 Celsius (yes that is
correct) without damage. They weren't "rated"
that high, but they could withstand that
temperature. They were rated for 60 Celsius (140 F).
Keep in mind that the cells will age
much more rapidly at that elevated temperature.
They perform better, however, and you don't hold
them that hot for very long. You must choose the
compromise between total life-span and
performance for the specific application, which
is typical for most things in life.
I'm not sure where you are getting your
information. Better check more than one source.
Bill D.
At 10:42 AM 4/1/2015, you wrote:
Jeff, I am not sure why performance at ambient
temperatures should make anyone feel confident
about a cell. LFP for instance, starts to have
serious difficulties at 104°F if it is fully
charged. That is certainly ambient here in
North Carolina; and that is free air, not boxed
up with significant amperage scooting about. I
must tell you, I don't have an axe to grind
here. I simply want to point out a better way
to go. That is to get better information for
all. And better testing with in the
industry. ENERDEL just popped up on my radar
is all. They have an website that is light on
good information and I waded in. I am happy to
see that behind the curtain they may have more
on the ball. I have been scanning the course
work you provided to me, and it is very
nice. When ENERDEL discusses cycle life (around
page 279) I can see they clearly understand the
reactivity of the positive electrode at very
high SOC and how temperature makes that much
worse for the electrolyte. They clearly have
good information to work with and probably are
engaged with Dalhousie University or the spin
off Novonix to get good testing done. I am duly
impressed. I still have not figured out what
chemistry they have chosen. From what I have
seen so far, they speak assiduously, only in
general terms regarding their own cells. If
they are using some inferior chemistry and
electrolyte package it is clearly not because
they don't know better, so I bet they are
OK. Provisional blessing on them until I am
better educated. Thanks for taking the time to
address this with me. Mike On Wed, Apr 1, 2015
at 10:19 AM, Jeff Major via EV
<[email protected]> wrote: > I doubt that
EnerDel and its customers have overlooked
anything as basic > as performance and life at
ambient temperatures. It appears to me that >
Hoegberg is comparing to some float stand-by
application and then > misinterpreting the
presented data. But whatever. They have
millions of > cells in the field and no
complaints of which I am aware. > >
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