li ion battery in cold weather

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li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Hi,

Does anyone have a more in-depth explanation why li ion cells perform
poorly in cold weather ? It's well known that your range goes down when
the battery is cold. Lots of writers talk about the phenomena and advise
you about it but fail to give any real explanations. I think this
conversation may have come up a long while ago but it's hard to search
for.

I did a bit of research. Some authors talk about "intercalation", which
happens below freezing. Intercalation is when the anode becomes plated
with lithium ions instead of the ions being absorbed into the anode.
Obviously, that permanently ruins the battery. So, this is irrelevant
regarding poor range in cold weather.

I did find one article that might be relevant, though.

https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html

They claim the electrolyte becomes viscous, slowing down the ion
movement. That's about all they say. But, I'll add my thoughts.

If the electrolyte is viscous, then I suspect the voltage potential
drops. Since watts-hours (energy) is V * Ah, you have less energy
available, assuming that the Ah is constant. But, what about internal
resistance ? For the same driving behavior, you'll need higher amps at a
lower voltage. Resistance loss is I^2 * R, so that loss should go up
significantly. I'm getting into a trap here: why doesn't the increased
resistance loss heat up the battery ? The nominal resistance is
extremely low, so maybe even at an elevated state there isn't enough
heat to affect the electrolyte's viscosity. Don't know.

Here's another article that talks about electrolyte. They talk about
preventing decomposition of electrolyte.
https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives

Obviously, the other major factors are cabin heat and defrost.

Peri

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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
You are confusing electric current with a chemical process. 
Ohms law does not apply in a chemical process. 
Low temperatures slow the chemical reaction and charge transfer velocity, which leads to the decrease of ionic conductivity in the electrolytes and lithium-ion diffusion within the electrodes. Such decrease will result in the reduction of energy and power capability, and sometimes even performance failure.


Sent from my iPhone
On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]> wrote:


Hi,

Does anyone have a more in-depth explanation why li ion cells perform poorly in cold weather ? It's well known that your range goes down when the battery is cold. Lots of writers talk about the phenomena and advise you about it but fail to give any real explanations. I think this conversation may have come up a long while ago but it's hard to search for.

I did a bit of research. Some authors talk about "intercalation", which happens below freezing. Intercalation is when the anode becomes plated with lithium ions instead of the ions being absorbed into the anode. Obviously, that permanently ruins the battery. So, this is irrelevant regarding poor range in cold weather.

I did find one article that might be relevant, though.

https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html

They claim the electrolyte becomes viscous, slowing down the ion movement. That's about all they say. But, I'll add my thoughts.

If the electrolyte is viscous, then I suspect the voltage potential drops. Since watts-hours (energy) is V * Ah, you have less energy available, assuming that the Ah is constant. But, what about internal resistance ? For the same driving behavior, you'll need higher amps at a lower voltage. Resistance loss is I^2 * R, so that loss should go up significantly. I'm getting into a trap here: why doesn't the increased resistance loss heat up the battery ? The nominal resistance is extremely low, so maybe even at an elevated state there isn't enough heat to affect the electrolyte's viscosity. Don't know.

Here's another article that talks about electrolyte. They talk about preventing decomposition of electrolyte.
https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives

Obviously, the other major factors are cabin heat and defrost.

Peri

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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Yes, it's the chemistry that results in slower ion transfer. But that
results in an electrical effect. I believe that effect is lower voltage
across the cell. Thus, how do you explain the fact that higher current,
I**R, means more heat ?

Peri

------ Original Message ------
From: "paul dove" <[hidden email]>
To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion
List" <[hidden email]>
Sent: 09-Sep-19 2:59:54 PM
Subject: Re: [EVDL] li ion battery in cold weather

>You are confusing electric current with a chemical process.
>
>Ohms law does not apply in a chemical process.
>
>Low temperatures slow the chemical reaction and charge transfer
>velocity, which leads to the decrease of ionic conductivity in the
>electrolytes and lithium-ion diffusion within the electrodes
><https://www.sciencedirect.com/science/article/pii/S1002007118307536#bib53>.
>Such decrease will result in the reduction of energy and power
>capability, and sometimes even performance failure.
>
>
>
>Sent from my iPhone
>
>On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]>
>wrote:
>
>>Hi,
>>
>>Does anyone have a more in-depth explanation why li ion cells perform
>>poorly in cold weather ? It's well known that your range goes down
>>when the battery is cold. Lots of writers talk about the phenomena and
>>advise you about it but fail to give any real explanations. I think
>>this conversation may have come up a long while ago but it's hard to
>>search for.
>>
>>I did a bit of research. Some authors talk about "intercalation",
>>which happens below freezing. Intercalation is when the anode becomes
>>plated with lithium ions instead of the ions being absorbed into the
>>anode. Obviously, that permanently ruins the battery. So, this is
>>irrelevant regarding poor range in cold weather.
>>
>>I did find one article that might be relevant, though.
>>
>>https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html
>>
>>They claim the electrolyte becomes viscous, slowing down the ion
>>movement. That's about all they say. But, I'll add my thoughts.
>>
>>If the electrolyte is viscous, then I suspect the voltage potential
>>drops. Since watts-hours (energy) is V * Ah, you have less energy
>>available, assuming that the Ah is constant. But, what about internal
>>resistance ? For the same driving behavior, you'll need higher amps at
>>a lower voltage. Resistance loss is I^2 * R, so that loss should go up
>>significantly. I'm getting into a trap here: why doesn't the increased
>>resistance loss heat up the battery ? The nominal resistance is
>>extremely low, so maybe even at an elevated state there isn't enough
>>heat to affect the electrolyte's viscosity. Don't know.
>>
>>Here's another article that talks about electrolyte. They talk about
>>preventing decomposition of electrolyte.
>>https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives
>>
>>Obviously, the other major factors are cabin heat and defrost.
>>
>>Peri
>>
>>_______________________________________________
>>UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>ARCHIVE: http://www.evdl.org/archive/index.html
>>INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>Please discuss EV drag racing at NEDRA
>>(http://groups.yahoo.com/group/NEDRA)
>>
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Ions are not the same as electrons. Ions are what moves _inside_ a
battery. Electrons are what moves _outside_ a battery.

Electrons travel at near the speed of light. Ions travel at far, far
lower speeds, (less than the speed of sound.) Ion must diffuse through
the solid or liquid in which they are surrounded.

Ions are indeed governed by the chemistry around them. Essentially, a
battery internally rusts, or corrodes, and you exploit that
electro-chemistry to get electricity.

The Arrhenius equation is what governs the chemical reactions that drive
the ions from one plate to the other inside a cell. There is a strong
temperature component to this equation.
https://en.wikipedia.org/wiki/Arrhenius_equation

The higher the temperature, the faster the reaction would like to occur.
In a cell, what holds back the chemical reaction (corrosion) is the lack
of electrons to feed the ionic reaction. If you give the reaction all
the electrons it wants, then the Arrhenius equation governs the speed of
the ion production, and the geometry of the cell governs the distance
that the ions must diffuse.

Bill D.

On 9/10/2019 10:23 AM, Peri Hartman via EV wrote:

> Yes, it's the chemistry that results in slower ion transfer. But that
> results in an electrical effect. I believe that effect is lower
> voltage across the cell. Thus, how do you explain the fact that higher
> current, I**R, means more heat ?
>
> Peri
>
> ------ Original Message ------
> From: "paul dove" <[hidden email]>
> To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion
> List" <[hidden email]>
> Sent: 09-Sep-19 2:59:54 PM
> Subject: Re: [EVDL] li ion battery in cold weather
>
>> You are confusing electric current with a chemical process.
>>
>> Ohms law does not apply in a chemical process.
>>
>> Low temperatures slow the chemical reaction and charge transfer
>> velocity, which leads to the decrease of ionic conductivity in the
>> electrolytes and lithium-ion diffusion within the electrodes
>> <https://www.sciencedirect.com/science/article/pii/S1002007118307536#bib53>.
>> Such decrease will result in the reduction of energy and power
>> capability, and sometimes even performance failure.
>>
>>
>>
>> Sent from my iPhone
>>
>> On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]>
>> wrote:
>>
>>> Hi,
>>>
>>> Does anyone have a more in-depth explanation why li ion cells
>>> perform poorly in cold weather ? It's well known that your range
>>> goes down when the battery is cold. Lots of writers talk about the
>>> phenomena and advise you about it but fail to give any real
>>> explanations. I think this conversation may have come up a long
>>> while ago but it's hard to search for.
>>>
>>> I did a bit of research. Some authors talk about "intercalation",
>>> which happens below freezing. Intercalation is when the anode
>>> becomes plated with lithium ions instead of the ions being absorbed
>>> into the anode. Obviously, that permanently ruins the battery. So,
>>> this is irrelevant regarding poor range in cold weather.
>>>
>>> I did find one article that might be relevant, though.
>>>
>>> https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html 
>>>
>>>
>>> They claim the electrolyte becomes viscous, slowing down the ion
>>> movement. That's about all they say. But, I'll add my thoughts.
>>>
>>> If the electrolyte is viscous, then I suspect the voltage potential
>>> drops. Since watts-hours (energy) is V * Ah, you have less energy
>>> available, assuming that the Ah is constant. But, what about
>>> internal resistance ? For the same driving behavior, you'll need
>>> higher amps at a lower voltage. Resistance loss is I^2 * R, so that
>>> loss should go up significantly. I'm getting into a trap here: why
>>> doesn't the increased resistance loss heat up the battery ? The
>>> nominal resistance is extremely low, so maybe even at an elevated
>>> state there isn't enough heat to affect the electrolyte's viscosity.
>>> Don't know.
>>>
>>> Here's another article that talks about electrolyte. They talk about
>>> preventing decomposition of electrolyte.
>>> https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives 
>>>
>>>
>>> Obviously, the other major factors are cabin heat and defrost.
>>>
>>> Peri
>>>
>>> _______________________________________________
>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>> ARCHIVE: http://www.evdl.org/archive/index.html
>>> INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>> Please discuss EV drag racing at NEDRA
>>> (http://groups.yahoo.com/group/NEDRA)
>>>
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
In reply to this post by Electric Vehicle Discussion List mailing list
Heat in a lithium ion battery is from two sources electrochemical operation and Joule heating. A way to calculate the battery heat is using a thermodynamic energy balance shown in equation below where the first term is the heat generation due to Joule heating and the second term is the heat generation due to entropy changes.
q= I(U-V) - I(T(dU/dV)

Bernadi D, Powlikowski E and Newman J 1985 A general energy balance for battery systems J.
Electrochem. Soc. 132 5-12
     
 
 

Sent from my iPhone

> On Sep 9, 2019, at 5:23 PM, Peri Hartman via EV <[hidden email]> wrote:
>
> Yes, it's the chemistry that results in slower ion transfer. But that results in an electrical effect. I believe that effect is lower voltage across the cell. Thus, how do you explain the fact that higher current, I**R, means more heat ?
>
> Peri
>
> ------ Original Message ------
> From: "paul dove" <[hidden email]>
> To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion List" <[hidden email]>
> Sent: 09-Sep-19 2:59:54 PM
> Subject: Re: [EVDL] li ion battery in cold weather
>
>> You are confusing electric current with a chemical process.
>>
>> Ohms law does not apply in a chemical process.
>>
>> Low temperatures slow the chemical reaction and charge transfer velocity, which leads to the decrease of ionic conductivity in the electrolytes and lithium-ion diffusion within the electrodes <https://www.sciencedirect.com/science/article/pii/S1002007118307536#bib53>. Such decrease will result in the reduction of energy and power capability, and sometimes even performance failure.
>>
>>
>>
>> Sent from my iPhone
>>
>>> On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]> wrote:
>>>
>>> Hi,
>>>
>>> Does anyone have a more in-depth explanation why li ion cells perform poorly in cold weather ? It's well known that your range goes down when the battery is cold. Lots of writers talk about the phenomena and advise you about it but fail to give any real explanations. I think this conversation may have come up a long while ago but it's hard to search for.
>>>
>>> I did a bit of research. Some authors talk about "intercalation", which happens below freezing. Intercalation is when the anode becomes plated with lithium ions instead of the ions being absorbed into the anode. Obviously, that permanently ruins the battery. So, this is irrelevant regarding poor range in cold weather.
>>>
>>> I did find one article that might be relevant, though.
>>>
>>> https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html
>>>
>>> They claim the electrolyte becomes viscous, slowing down the ion movement. That's about all they say. But, I'll add my thoughts.
>>>
>>> If the electrolyte is viscous, then I suspect the voltage potential drops. Since watts-hours (energy) is V * Ah, you have less energy available, assuming that the Ah is constant. But, what about internal resistance ? For the same driving behavior, you'll need higher amps at a lower voltage. Resistance loss is I^2 * R, so that loss should go up significantly. I'm getting into a trap here: why doesn't the increased resistance loss heat up the battery ? The nominal resistance is extremely low, so maybe even at an elevated state there isn't enough heat to affect the electrolyte's viscosity. Don't know.
>>>
>>> Here's another article that talks about electrolyte. They talk about preventing decomposition of electrolyte.
>>> https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives
>>>
>>> Obviously, the other major factors are cabin heat and defrost.
>>>
>>> Peri
>>>
>>> _______________________________________________
>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>> ARCHIVE: http://www.evdl.org/archive/index.html
>>> INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>> Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>>>
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
In reply to this post by Electric Vehicle Discussion List mailing list
Understand. Well mostly: I didn't lookup Arrhenius.

But my question still remains. What is the electrical result when the
reaction is slower. I am presuming there is a lower voltage across the
cell. And, if that's so, more current must come from the battery to
provide the same driving experience. Is this correct ?

And if it's correct, then the cell's internal resistance must come into
play. Is it simply not significant enough to warm up the cell ?

Peri

------ Original Message ------
From: "Bill Dube via EV" <[hidden email]>
To: [hidden email]
Cc: "Bill Dube" <[hidden email]>
Sent: 09-Sep-19 4:59:04 PM
Subject: Re: [EVDL] li ion battery in cold weather

>Ions are not the same as electrons. Ions are what moves _inside_ a battery. Electrons are what moves _outside_ a battery.
>
>Electrons travel at near the speed of light. Ions travel at far, far lower speeds, (less than the speed of sound.) Ion must diffuse through the solid or liquid in which they are surrounded.
>
>Ions are indeed governed by the chemistry around them. Essentially, a battery internally rusts, or corrodes, and you exploit that electro-chemistry to get electricity.
>
>The Arrhenius equation is what governs the chemical reactions that drive the ions from one plate to the other inside a cell. There is a strong temperature component to this equation.
>https://en.wikipedia.org/wiki/Arrhenius_equation
>
>The higher the temperature, the faster the reaction would like to occur. In a cell, what holds back the chemical reaction (corrosion) is the lack of electrons to feed the ionic reaction. If you give the reaction all the electrons it wants, then the Arrhenius equation governs the speed of the ion production, and the geometry of the cell governs the distance that the ions must diffuse.
>
>Bill D.
>
>On 9/10/2019 10:23 AM, Peri Hartman via EV wrote:
>>Yes, it's the chemistry that results in slower ion transfer. But that results in an electrical effect. I believe that effect is lower voltage across the cell. Thus, how do you explain the fact that higher current, I**R, means more heat ?
>>
>>Peri
>>
>>------ Original Message ------
>>From: "paul dove" <[hidden email]>
>>To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion List" <[hidden email]>
>>Sent: 09-Sep-19 2:59:54 PM
>>Subject: Re: [EVDL] li ion battery in cold weather
>>
>>>You are confusing electric current with a chemical process.
>>>
>>>Ohms law does not apply in a chemical process.
>>>
>>>Low temperatures slow the chemical reaction and charge transfer velocity, which leads to the decrease of ionic conductivity in the electrolytes and lithium-ion diffusion within the electrodes <https://www.sciencedirect.com/science/article/pii/S1002007118307536#bib53>. Such decrease will result in the reduction of energy and power capability, and sometimes even performance failure.
>>>
>>>
>>>
>>>Sent from my iPhone
>>>
>>>On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]> wrote:
>>>
>>>>Hi,
>>>>
>>>>Does anyone have a more in-depth explanation why li ion cells perform poorly in cold weather ? It's well known that your range goes down when the battery is cold. Lots of writers talk about the phenomena and advise you about it but fail to give any real explanations. I think this conversation may have come up a long while ago but it's hard to search for.
>>>>
>>>>I did a bit of research. Some authors talk about "intercalation", which happens below freezing. Intercalation is when the anode becomes plated with lithium ions instead of the ions being absorbed into the anode. Obviously, that permanently ruins the battery. So, this is irrelevant regarding poor range in cold weather.
>>>>
>>>>I did find one article that might be relevant, though.
>>>>
>>>>https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html
>>>>
>>>>They claim the electrolyte becomes viscous, slowing down the ion movement. That's about all they say. But, I'll add my thoughts.
>>>>
>>>>If the electrolyte is viscous, then I suspect the voltage potential drops. Since watts-hours (energy) is V * Ah, you have less energy available, assuming that the Ah is constant. But, what about internal resistance ? For the same driving behavior, you'll need higher amps at a lower voltage. Resistance loss is I^2 * R, so that loss should go up significantly. I'm getting into a trap here: why doesn't the increased resistance loss heat up the battery ? The nominal resistance is extremely low, so maybe even at an elevated state there isn't enough heat to affect the electrolyte's viscosity. Don't know.
>>>>
>>>>Here's another article that talks about electrolyte. They talk about preventing decomposition of electrolyte.
>>>>https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives
>>>>
>>>>Obviously, the other major factors are cabin heat and defrost.
>>>>
>>>>Peri
>>>>
>>>>_______________________________________________
>>>>UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
>>>>ARCHIVE: http://www.evdl.org/archive/index.html
>>>>INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
>>>>Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
>>>>
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
On Tue, 10 Sep 2019 at 15:52, Peri Hartman via EV <[hidden email]> wrote:

> And if it's correct, then the cell's internal resistance must come into
> play. Is it simply not significant enough to warm up the cell ?

It can be enough to warm the cell. The original Thundersky cells had
quite high internal resistance anyway and Cedric Lynch discovered in
his machine, that it was better to discharge the cells quite hard
initially and generate some heat, than it was to baby them at low
temperatures.

--
Paul Compton
www.morini-mania.co.uk
www.paulcompton.co.uk (YouTube channel)
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Ok, so the correct assumption would be that the Leaf and Bolt cells
don't have enough internal resistance, thus the performance stays poor
in cold weather ?

------ Original Message ------
From: "Paul Compton via EV" <[hidden email]>
To: "Peri Hartman via EV" <[hidden email]>
Cc: "Paul Compton" <[hidden email]>
Sent: 10-Sep-19 8:15:39 AM
Subject: Re: [EVDL] li ion battery in cold weather

>On Tue, 10 Sep 2019 at 15:52, Peri Hartman via EV <[hidden email]> wrote:
>
>>  And if it's correct, then the cell's internal resistance must come into
>>  play. Is it simply not significant enough to warm up the cell ?
>
>It can be enough to warm the cell. The original Thundersky cells had
>quite high internal resistance anyway and Cedric Lynch discovered in
>his machine, that it was better to discharge the cells quite hard
>initially and generate some heat, than it was to baby them at low
>temperatures.
>
>--
>Paul Compton
>www.morini-mania.co.uk
>www.paulcompton.co.uk (YouTube channel)
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Re: li ion battery in cold weather

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In reply to this post by Electric Vehicle Discussion List mailing list
Peri Hartman via EV wrote:
> Understand. Well mostly: I didn't lookup Arrhenius.
>
> But my question still remains. What is the electrical result when the
> reaction is slower. I am presuming there is a lower voltage across the
> cell. And, if that's so, more current must come from the battery to
> provide the same driving experience. Is this correct ?
>
> And if it's correct, then the cell's internal resistance must come into
> play. Is it simply not significant enough to warm up the cell ?

The cell voltage barely changes at all with temperature. There is a tiny
temperature coefficient, but it is "lost in the noise" with variations
in state of charge, age of the cell, manufacturing variations, etc.

But you only see this voltage under no load; a long time after any
charging or discharging.

The internal resistance *does* change with temperature. This is the
parameter affected by the Arrhenius equation. A cold cell has high
internal resistance; and that's what prevents it from being loaded or
charged at high current.

--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
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Re: li ion battery in cold weather

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In reply to this post by Electric Vehicle Discussion List mailing list
Peri Hartman via EV wrote:
> Ok, so the correct assumption would be that the Leaf and Bolt cells
> don't have enough internal resistance, thus the performance stays poor
> in cold weather ?

Let me try to simplify it. There are huge differences between the
various types of lithium cell constructions and chemistries. Don't
assume that the same rules apply to all of them. It's like assuming that
all dogs are alike. They may all be dogs; but there are vast differences
between them!

The old Thundersky cells had very high internal resistance; more than 10
times higher than modern cells. Since the resistance was so high, it was
a more effective "heater". They also had a very thick plastic case,
which insulated and trapped the heat. So Cedric's trick worked.

It won't work for modern low-resistance cells with good cooling. Loading
a cold cell with high current will cause a little heating (which helps).
But it will also cause significant damage from side effects. The normal
chemical reactions can't supply the current due to the cold; so this
forces side reactions to take place, damaging the cell.

Lee Hart

--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: li ion battery in cold weather

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 During discharge Lithium ions are dissociated from the anode and migrate across the electrolyte and are inserted into the crystal structure of the host compound. At the same time the compensating electrons travel in the external circuit and are accepted by the host to balance the reaction. The process is completely reversible during charge. Thus the Lithium ions pass back and forth between the electrodes during charging and discharging. There is a protective layer between the separator and the anode the solid electrolyte Interface (SEI). The SEI layer is necessary but it increases the cell internal impedance and reduces charge rates. This layer increases with age increasing impedance and reducing capacity. Low temperatures cause Lithium Plating on the (anode) negative electrode SEI layer causing a permanent loss of capacity, slowing down the movement of ions because of lower ionic conductivity and an increasing the charge transfer resistance.

Lithium Ion transfer is directly proportional to electron transfer outside the battery.

 

-----Original Appointment-----
From: Honeycutt, John H. (MSFC-XP01) <[hidden email]>
Sent: Monday, December 17, 2018 3:22 PM
To: Honeycutt, John H. (MSFC-XP01); Counce, Terri Hill (MSFC-XP03);ESTES, KATHERINE DEWITT (MSFC-XP03); Hutt, John J. (MSFC-XP04); Dove, Paul A.(MSFC-XP10); Reynolds, Dave (MSFC-XP10); Cartagena, Wilfredo (MSFC-XP30); Gill,Hansel D.v (MSFC-XP30); Stough, Robert W. (MSFC-XP50); Mclemore, Carole A.(MSFC-XP50)
Cc: Hester, Kate (MSFC-XP02)[MIPSS PC]; Cobb, Sharon D (MSFC-XP02);Cianciola, Chris (MSFC-XP01)
Subject: Skip Level Breakfast
When: Tuesday, September 17, 2019 8:00 AM-9:00 AM (UTC-06:00) CentralTime (US & Canada).
Where: 4220/5106

 

 

I would like to invite you tojoin me for an informal chat and breakfast on Tuesday,September 17 from 8:00am-9:00am in 4220/5106.  I want to take timeeach month to sit down with people from across the program to get to know eachof you better, learn more about what you do in your current task, hear what’son your mind, and provide a way for employees from different groups to get toknow each other better.  If you have any questions please contact ourevents coordinator, Kate Hester ([hidden email]).

 

Please use the “sendresponse” option when accepting or declining so we can track RSVPs.

 

Sincerely,

John Honeycutt

 

    On Tuesday, September 10, 2019, 9:53:01 AM CDT, Peri Hartman via EV <[hidden email]> wrote:  
 
 Understand. Well mostly: I didn't lookup Arrhenius.

But my question still remains. What is the electrical result when the
reaction is slower. I am presuming there is a lower voltage across the
cell. And, if that's so, more current must come from the battery to
provide the same driving experience. Is this correct ?

And if it's correct, then the cell's internal resistance must come into
play. Is it simply not significant enough to warm up the cell ?

Peri

------ Original Message ------
From: "Bill Dube via EV" <[hidden email]>
To: [hidden email]
Cc: "Bill Dube" <[hidden email]>
Sent: 09-Sep-19 4:59:04 PM
Subject: Re: [EVDL] li ion battery in cold weather

>Ions are not the same as electrons. Ions are what moves _inside_ a battery. Electrons are what moves _outside_ a battery.
>
>Electrons travel at near the speed of light. Ions travel at far, far lower speeds, (less than the speed of sound.) Ion must diffuse through the solid or liquid in which they are surrounded.
>
>Ions are indeed governed by the chemistry around them. Essentially, a battery internally rusts, or corrodes, and you exploit that electro-chemistry to get electricity.
>
>The Arrhenius equation is what governs the chemical reactions that drive the ions from one plate to the other inside a cell. There is a strong temperature component to this equation.
>https://en.wikipedia.org/wiki/Arrhenius_equation
>
>The higher the temperature, the faster the reaction would like to occur. In a cell, what holds back the chemical reaction (corrosion) is the lack of electrons to feed the ionic reaction. If you give the reaction all the electrons it wants, then the Arrhenius equation governs the speed of the ion production, and the geometry of the cell governs the distance that the ions must diffuse.
>
>Bill D.
>
>On 9/10/2019 10:23 AM, Peri Hartman via EV wrote:
>>Yes, it's the chemistry that results in slower ion transfer. But that results in an electrical effect. I believe that effect is lower voltage across the cell. Thus, how do you explain the fact that higher current, I**R, means more heat ?
>>
>>Peri
>>
>>------ Original Message ------
>>From: "paul dove" <[hidden email]>
>>To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion List" <[hidden email]>
>>Sent: 09-Sep-19 2:59:54 PM
>>Subject: Re: [EVDL] li ion battery in cold weather
>>
>>>You are confusing electric current with a chemical process.
>>>
>>>Ohms law does not apply in a chemical process.
>>>
>>>Low temperatures slow the chemical reaction and charge transfer velocity, which leads to the decrease of ionic conductivity in the electrolytes and lithium-ion diffusion within the electrodes <https://www.sciencedirect.com/science/article/pii/S1002007118307536#bib53>. Such decrease will result in the reduction of energy and power capability, and sometimes even performance failure.
>>>
>>>
>>>
>>>Sent from my iPhone
>>>
>>>On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]> wrote:
>>>
>>>>Hi,
>>>>
>>>>Does anyone have a more in-depth explanation why li ion cells perform poorly in cold weather ? It's well known that your range goes down when the battery is cold. Lots of writers talk about the phenomena and advise you about it but fail to give any real explanations. I think this conversation may have come up a long while ago but it's hard to search for.
>>>>
>>>>I did a bit of research. Some authors talk about "intercalation", which happens below freezing. Intercalation is when the anode becomes plated with lithium ions instead of the ions being absorbed into the anode. Obviously, that permanently ruins the battery. So, this is irrelevant regarding poor range in cold weather.
>>>>
>>>>I did find one article that might be relevant, though.
>>>>
>>>>https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html
>>>>
>>>>They claim the electrolyte becomes viscous, slowing down the ion movement. That's about all they say. But, I'll add my thoughts.
>>>>
>>>>If the electrolyte is viscous, then I suspect the voltage potential drops. Since watts-hours (energy) is V * Ah, you have less energy available, assuming that the Ah is constant. But, what about internal resistance ? For the same driving behavior, you'll need higher amps at a lower voltage. Resistance loss is I^2 * R, so that loss should go up significantly. I'm getting into a trap here: why doesn't the increased resistance loss heat up the battery ? The nominal resistance is extremely low, so maybe even at an elevated state there isn't enough heat to affect the electrolyte's viscosity. Don't know.
>>>>
>>>>Here's another article that talks about electrolyte. They talk about preventing decomposition of electrolyte.
>>>>https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives
>>>>
>>>>Obviously, the other major factors are cabin heat and defrost.
>>>>
>>>>Peri
>>>>
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>>>>
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Re: li ion battery in cold weather

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Thanks.

So the correct conclusion would be, for those cars which have poor
winter range, that the cell internal resistance is too low to heat the
cell ?

Also, that the cell voltage is lower during cold temps (while under
load), resulting in less Wh ?

Peri

------ Original Message ------
From: "Lee Hart" <[hidden email]>
To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion
List" <[hidden email]>
Sent: 10-Sep-19 10:25:44 AM
Subject: Re: [EVDL] li ion battery in cold weather

>Peri Hartman via EV wrote:
>>Ok, so the correct assumption would be that the Leaf and Bolt cells
>>don't have enough internal resistance, thus the performance stays poor
>>in cold weather ?
>
>Let me try to simplify it. There are huge differences between the various types of lithium cell constructions and chemistries. Don't assume that the same rules apply to all of them. It's like assuming that all dogs are alike. They may all be dogs; but there are vast differences between them!
>
>The old Thundersky cells had very high internal resistance; more than 10 times higher than modern cells. Since the resistance was so high, it was a more effective "heater". They also had a very thick plastic case, which insulated and trapped the heat. So Cedric's trick worked.
>
>It won't work for modern low-resistance cells with good cooling. Loading a cold cell with high current will cause a little heating (which helps). But it will also cause significant damage from side effects. The normal chemical reactions can't supply the current due to the cold; so this forces side reactions to take place, damaging the cell.
>
>Lee Hart
>
>-- There is a computer disease that anybody who works with computers knows
>about. It's very serious, and interferes completely with your work. The
>trouble with computers is that you 'play' with them! (Richard Feynman)
>--
>Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Peri Hartman via EV wrote:
> So the correct conclusion would be, for those cars which have poor
> winter range, that the cell internal resistance is too low to heat the
> cell ?

Yes; too little self-heating to be useful.

> Also, that the cell voltage is lower during cold temps (while under
> load), resulting in less Wh ?

The voltage *under load* is lower. You can get few KWH out before it
falls too low *under load* to be safe to continue using.

Note that the KWH are all still in there -- you just can't get them out.
Think of a bucket of water that's half-frozen. You can only get out the
half that isn't frozen. But let it warm up, and the rest of the water is
still there.

--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: li ion battery in cold weather

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Below, please.

------ Original Message ------
From: "Lee Hart" <[hidden email]>
To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion
List" <[hidden email]>
Sent: 10-Sep-19 11:18:12 AM
Subject: Re: [EVDL] li ion battery in cold weather

>Peri Hartman via EV wrote:
>>So the correct conclusion would be, for those cars which have poor
>>winter range, that the cell internal resistance is too low to heat the
>>cell ?
>
>Yes; too little self-heating to be useful.
>
>>Also, that the cell voltage is lower during cold temps (while under
>>load), resulting in less Wh ?
>
>The voltage *under load* is lower. You can get few KWH out before it falls too low *under load* to be safe to continue using.
>
>Note that the KWH are all still in there -- you just can't get them out. Think of a bucket of water that's half-frozen. You can only get out the half that isn't frozen. But let it warm up, and the rest of the water is still there.
In other words, when cold, the voltage drops below the safe minimum
rated value ? But if warmed up, the voltage rises enough to use the cell
longer ?

Ok, then why don't battery heaters - which I thought the Bolt & Tesla
have - give a good winter range ?
>
>
>-- There is a computer disease that anybody who works with computers knows
>about. It's very serious, and interferes completely with your work. The
>trouble with computers is that you 'play' with them! (Richard Feynman)
>--
>Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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Re: li ion battery in cold weather

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Peri Hartman via EV wrote:
> In other words, when cold, the voltage drops below the safe minimum
> rated value ? But if warmed up, the voltage rises enough to use the cell
> longer ?

Yes. You've got it!

> Ok, then why don't battery heaters - which I thought the Bolt & Tesla
> have - give a good winter range ?

They *do* work (at least, I assume they do). I have a 2013 Leaf. In the
summer, it gets 80-100 miles range. In the winter when it sits outside
at 0 deg.F, it gets 30-40 miles range. But if it's in the garage (at
about 50 deg.F) and we drive it at 0 deg.F, the range is 60-70 miles.

Now, there is some loss of range from other sources. In winter, the
heater is on; that takes power. The tires are stiffer, the road may be
wet or snow-covered, the lubricants are thicker, there may be snow or
ice on the car that add weight and worsen aerodynamices, etc.

On battery heaters: Where does it get its power? On the Leaf, it is
powered by the battery, but doesn't turn on until -14 deg.F. So it has
no effect until it *really* gets cold! How do the ones in the Tesla or
Bolt work?

--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: li ion battery in cold weather

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> Ok, then why don't battery heaters - which I thought the Bolt & Tesla
> have - give a good winter range ?

Because there is a balance temperature point above which you are burning
more kW just warming up the battery than you get in better range for the
same kWh..  In either case range in winter is less because the battery is
cold or you are using up kWh for warming the battery.  Either way, reduced
range.

bob
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Re: li ion battery in cold weather

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I'm really surprised the "balance" is so poor. If the battery has
reasonable insulation, how much power would it take to keep it warm -
e.g. 50F - for, say 8 hours ? Let's say the outside temp is 0F average.

I don't expect anyone to do calculations. But Lee gives an approx metric
of 30-40 miles when cold and 60-70 miles when the battery is 50F, both
with 0F temp outside. It seems fair to surmise that the difference in
range is due to the temp of the battery. For the 2013 model, I think it
has a 30kWh battery. That means that roughly half of the battery's kWh
is not usable when the battery is at 0F, or about 15kWh. Really, for an
insulated battery, it would take that much energy to keep it warm while
you're out doing something ?

Let me give a real life example. Let's say I buy a Bolt and want to use
it to go skiing. It's 160 miles RT. The average temp while at the ski
area parking might be 25F (hopefully not 0 :). I want to be sure I can
get home without stopping to charge somewhere. If I can heat the battery
while skiing, I should have no problem. If not, I'm probably ok in this
scenario, but not with too much margin. (A lot of hand waving calcs
going on, I know.)

For this wave of early adopters, it's not that big a deal. My guess is
that there's virtually no insulation and the manufacturers are skimping
because it won't matter so much to the current buyers. But if the
manufacturers want to sell mainstream, I think this will come back as a
serious red flag for many buyers. Of course, in the mean time, we're
getting better technology...

Peri

------ Original Message ------
From: "Robert Bruninga" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>; "Peri
Hartman" <[hidden email]>
Cc: "Lee Hart" <[hidden email]>
Sent: 10-Sep-19 12:05:06 PM
Subject: RE: [EVDL] li ion battery in cold weather

>>  Ok, then why don't battery heaters - which I thought the Bolt & Tesla
>>  have - give a good winter range ?
>
>Because there is a balance temperature point above which you are burning
>more kW just warming up the battery than you get in better range for the
>same kWh..  In either case range in winter is less because the battery is
>cold or you are using up kWh for warming the battery.  Either way, reduced
>range.
>
>bob

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Re: li ion battery in cold weather

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Peri Hartman via EV wrote:
> I'm really surprised the "balance" is so poor...  My guess is that there's
> virtually no insulation and the manufacturers are skimping because it won't
> matter so much to the current buyers.

I think that is exactly it. Also, the big automakers have so little
experience with EVs that they don't realize they need battery
insulation. And, they don't tend to listen to advice from outside the
company.

I've learned myself that even 1" of styrafoam insulation is enough to
keep a half ton of batteries at 70 deg.F with just 100-200w of heat. A
30 KHW battery pack could supply 100w for almost 2 weeks! And if you
leave the card plugged in, that 100w can come from the AC line; not the
pack itself.

--
There is a computer disease that anybody who works with computers knows
about. It's very serious, and interferes completely with your work. The
trouble with computers is that you 'play' with them! (Richard Feynman)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: li ion battery in cold weather

Electric Vehicle Discussion List mailing list
Ok, case closed !
Thanks everyone for your input.
Peri

------ Original Message ------
From: "Lee Hart" <[hidden email]>
To: "Peri Hartman" <[hidden email]>; "Electric Vehicle Discussion
List" <[hidden email]>
Sent: 10-Sep-19 2:19:14 PM
Subject: Re: [EVDL] li ion battery in cold weather

>Peri Hartman via EV wrote:
>>I'm really surprised the "balance" is so poor...  My guess is that there's
>>virtually no insulation and the manufacturers are skimping because it won't
>>matter so much to the current buyers.
>
>I think that is exactly it. Also, the big automakers have so little experience with EVs that they don't realize they need battery insulation. And, they don't tend to listen to advice from outside the company.
>
>I've learned myself that even 1" of styrafoam insulation is enough to keep a half ton of batteries at 70 deg.F with just 100-200w of heat. A 30 KHW battery pack could supply 100w for almost 2 weeks! And if you leave the card plugged in, that 100w can come from the AC line; not the pack itself.
>
>-- There is a computer disease that anybody who works with computers knows
>about. It's very serious, and interferes completely with your work. The
>trouble with computers is that you 'play' with them! (Richard Feynman)
>--
>Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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Re: li ion battery in cold weather

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In reply to this post by Electric Vehicle Discussion List mailing list
I am late to this discussion and have little to add, but this called me to
comment:

"I did a bit of research. Some authors talk about "intercalation", which
happens below freezing. Intercalation is when the anode becomes plated with
lithium ions instead of the ions being absorbed into the anode."

I don't know the authors referred to, but this is an incorrect definition
of intercalation. Intercalation is the nestling of Li ions between sheets
of graphene in the anode. It happens are all temperatures, not only below
freezing.
[Here is a hoard of images describing intercalation:  <goog_1326516460>
http://tinyurl.com/y46elflk]

Intercalation has nothing to do with Li plating onto the anode.
Intercalation of the ions is what makes Li ion cells so much better than
PbSO4, and why there is little decrease in the state of charge if a cell
sits for a long time. The ions sort of drop into little pockets of the
hexagonal structure of carbon in graphene. It is a stable condition. I base
this on the Waterloo lecture by Dr. Jeff Dahn,and other reference material.
I am old enough to forget stuff, but I am pretty certain of this.

The decrease in cell function due to plating is purely mechanical. The
anode needs to be porous enough that ions pass from the electrolyte easily.
he plating of the Li on the SEI (solid electrolyte interphase) of the anode
simply blocks the passage of ions and reduces their ability to penetrate
the anode. It clogs the screen so to speak. This is not intercalation it is
simple plating.

Clotting up the SEI of the anode nd degredation of the electrolyte are
significant causes of cell dysfunction. the discharged cathode is highly
reactive and mess with the electrolyte. A lot of improvements in Li ion
cells is additives to make the electrolyte less easily damaged when the
cell is fully charged. Heat is also a factor when the cell is fully
charged. This is a good reason to mostly charge no more than 80% or 90% of
100% SOC. It keeps the positive electrode from becoming fully reactive and
starting to tear up the electrolyte.

Back the subject of cold performance. Part of the problem is simply
increased viscosity of the electrolyte leading to lower mobility of the
ions. I am not sure what is going on with electrolyte formulation, but
lower viscosity was one of the main paths of interest 5 years ago.

A little OT: some electrochemists are averse to talking about anodes and
cathodes preferring to refer to the positive and negative electrodes. This
is because the words anode and cathode apparently change meaning depending
on whether a cell is charging or discharging. Referring to positive and
negative electrodes eliminates confusion.

The purchase and application of the graphene has a major effect on cell
capacity. Definitely non-trivial. You don't just smear some carbon on a
sheet of copper. (You could make a Li ion cell in your garage, but it would
be limited by your ability to make a quality application of the graphene.)
Cell capacity 5 years ago was limited by the ability of the graphene to
make proper orientation in the manufactured electrode, and therefore the
availability of sites for intercalation iwas limited. A cell with
theoretically perfect graphene formation would be many times greater in
capacity.

Mike






On Mon, Sep 9, 2019 at 8:12 PM paul dove via EV <[hidden email]> wrote:

> You are confusing electric current with a chemical process.
> Ohms law does not apply in a chemical process.
> Low temperatures slow the chemical reaction and charge transfer
> velocity, which leads to the decrease of ionic conductivity in the
> electrolytes and lithium-ion diffusion within the electrodes. Such decrease
> will result in the reduction of energy and power capability, and sometimes
> even performance failure.
>
>
> Sent from my iPhone
> On Sep 9, 2019, at 12:38 PM, Peri Hartman via EV <[hidden email]>
> wrote:
>
>
> Hi,
>
> Does anyone have a more in-depth explanation why li ion cells perform
> poorly in cold weather ? It's well known that your range goes down when the
> battery is cold. Lots of writers talk about the phenomena and advise you
> about it but fail to give any real explanations. I think this conversation
> may have come up a long while ago but it's hard to search for.
>
> I did a bit of research. Some authors talk about "intercalation", which
> happens below freezing. Intercalation is when the anode becomes plated with
> lithium ions instead of the ions being absorbed into the anode. Obviously,
> that permanently ruins the battery. So, this is irrelevant regarding poor
> range in cold weather.
>
> I did find one article that might be relevant, though.
>
>
> https://cen.acs.org/articles/96/i10/Rechargeable-battery-weathers-extreme-cold-conditions.html
>
> They claim the electrolyte becomes viscous, slowing down the ion movement.
> That's about all they say. But, I'll add my thoughts.
>
> If the electrolyte is viscous, then I suspect the voltage potential drops.
> Since watts-hours (energy) is V * Ah, you have less energy available,
> assuming that the Ah is constant. But, what about internal resistance ? For
> the same driving behavior, you'll need higher amps at a lower voltage.
> Resistance loss is I^2 * R, so that loss should go up significantly. I'm
> getting into a trap here: why doesn't the increased resistance loss heat up
> the battery ? The nominal resistance is extremely low, so maybe even at an
> elevated state there isn't enough heat to affect the electrolyte's
> viscosity. Don't know.
>
> Here's another article that talks about electrolyte. They talk about
> preventing decomposition of electrolyte.
>
> https://spectrum.ieee.org/energywise/green-tech/fuel-cells/lithium-additives
>
> Obviously, the other major factors are cabin heat and defrost.
>
> Peri
>
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--
Michael E. Ross
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