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) <[email protected]> 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 ([email protected]). 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 <[email protected]> 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" <[email protected]> To: [email protected] Cc: "Bill Dube" <[email protected]> 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" <[email protected]> >>To: "Peri Hartman" <[email protected]>; "Electric Vehicle Discussion List" >><[email protected]> >>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 <[email protected]> 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) >>>> >>-------------- next part -------------- >>An HTML attachment was scrubbed... >>URL: >><http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190909/a522d033/attachment.html> >>_______________________________________________ >>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) >> >> > >-------------- next part -------------- >An HTML attachment was scrubbed... >URL: ><http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20190910/71e01d06/attachment.html> >_______________________________________________ >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) > _______________________________________________ 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) -------------- next part -------------- An HTML attachment was scrubbed... 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