Battery Progress

SpaceYooper

Well-known member
Joined
May 23, 2020
Threads
44
Messages
835
Reaction score
1,490
Location
Colorado Springs
Vehicles
13' F150, 17' Explorer, 13' Cruz, 13' Clubman
Occupation
Retired USSF SNCO, REALTOR®
Country flag
Tesla battery research group unveils paper on new high-energy-density battery that could last 100 years
Fred Lambert - May. 24th 2022 3:26 am @FredericLambert

https://electrek.co/2022/05/24/tesl...r-high-energy-density-battery-last-100-years/

Tesla’s advanced battery research group in Canada in partnership with Dalhousie University has released a new paper on a new nickel-based battery that could last 100 years while still favorably comparing to LFP cells on charging and energy density.

Back in 2016, Tesla established its “Tesla Advanced Battery Research” in Canada through a partnership with Jeff Dahn’s battery lab at Dalhousie University in Halifax, Canada.

Dahn is considered a pioneer in Li-ion battery cells. He has been working on the Li-ion batteries pretty much since they were invented. He is credited for helping to increase the life cycle of the cells, which helped their commercialization.

His work now focuses mainly on a potential increase in energy density and durability, while also decreasing the cost.

The group has already produced quite a few patents and papers on batteries for Tesla. The automaker recently extended its contract with the group through 2026 as it added two new leaders to be mentored by Dahn.

One of those new leaders, Michael Metzger, along with Dahn himself, and a handful of PhDs in the program, are named as authors of a new research paper called “Li[Ni0.5Mn0.3Co0.2]O2 as a Superior Alternative to LiFePO4 for Long-Lived Low Voltage Li-Ion Cells” in the Journal of the Electrochemical Society.

The paper describes a nickel-based battery chemistry meant to compete with LFP battery cells on longevity while retaining the properties that people like in nickel-based batteries, like higher energy density, which enables longer range with fewer batteries for electric vehicles.

The group wrote in the paper’s abstract:

Single crystal Li[Ni0.5Mn0.3Co0.2]O2//graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥4.2 V) were cycled with charging to either 3.65 V or 3.80 V to facilitate comparison with LiFePO4//graphite (LFP) pouch cells on the grounds of similar maximum charging potential and similar negative electrode utilization. The NMC532 cells, when constructed with only sufficient graphite to be charged to 3.80 V, have an energy density that exceeds that of the LFP cells and a cycle-life that greatly exceeds that of the LFP cells at 40 °C, 55 °C and 70 °C. Excellent lifetime at high temperature is demonstrated with electrolytes that contain lithium bis(fluorosulfonyl)imide (LiFSI) salt, well beyond those provided by conventional LiPF6 electrolytes.
The cells showed an impressive capacity retention over a high number of cycles:

Tesla Cybertruck Battery Progress 1653398029934


The research group even noted that the new cell described in the paper could last a 100 years if the temperature is controlled at 25C:

Ultra-high precision coulometry and electrochemical impedance spectroscopy are used to complement cycling results and investigate the reasons for the improved performance of the NMC cells. NMC cells, particularly those balanced and charged to 3.8 V, show better coulombic efficiency, less capacity fade and higher energy density compared to LFP cells and are projected to yield lifetimes approaching a century at 25 °C.
One of the keys appears to be using an electrolyte with LiFSI lithium salts, and the paper notes that the benefits could also apply to other nickel-based chemistries, including those with no or low cobalt.

FTC: We use income earning auto affiliate links. More.
Sponsored

 
OP
OP
SpaceYooper

SpaceYooper

Well-known member
Joined
May 23, 2020
Threads
44
Messages
835
Reaction score
1,490
Location
Colorado Springs
Vehicles
13' F150, 17' Explorer, 13' Cruz, 13' Clubman
Occupation
Retired USSF SNCO, REALTOR®
Country flag
The tech is getting better but I still have some battery questions.

1. When an battery degrades does the cost per mile increase? I know some people here have said no, and to think about more like your gas tank shrinking. So it does not cost the same to "fuel up". I just want to confirm this or hear if someone think otherwise.

For example if a brand new battery costs $25 to charge to give 500 miles of range, does a 50% degraded battery still cost $25 to charge but only give 250 miles of range? Or is it only going to cost $12.50 and only give 250 miles of range? Essentially meaning the cost per mile cost per mile stays the same.

If it is the case that the "tank" gets smaller and the cost per mile stays the same...does the cost per mile really stay the same? I've read that as a battery degrades the impedance of the battery increases. This impedance change would make charging less efficient. So it would actually cost a little more per mile with the degraded battery. Does anyone have any metrics or stats on this? I'm assuming is very slight, but I don't know.

2. How does Tesla handle their batter charging? We know full discharging and full charging are bad for the life of the battery. I think each of the car companies handle this problem differently. I believe some manufacturers don't allow the the battery get below a 20% charge or above 80%. They distinguish between gross vs net battery capacity. Effectively 20%-80% is your 0%-100% on your gauge.

I'm under the impression that Tesla does not do this. Tesla allows you to charge to 100% of the gross battery capacity and discharge below 20%, but advise you not to do so. Basically they leave it up to the owner to properly manage their batteries. Is this true or false?

3. What's worse for the battery; discharging to 0% or charging to 100? From what I have read it seems like the discharging too a very low % is worse for the battery, but then I've also heard the the heat while trying to get that full charge is also bad for the battery. So if I change the numbers a little, what is worse; discharging to 10% or charging to 100% using a Supercharger? An finally what if I discharge to 10% but recharge to 100% at home using a low and slow method?
 

Crissa

Well-known member
First Name
Crissa
Joined
Jul 8, 2020
Threads
126
Messages
16,211
Reaction score
27,071
Location
Santa Cruz
Vehicles
2014 Zero S, 2013 Mazda 3
Country flag
The tech is getting better but I still have some battery questions.

1. When an battery degrades does the cost per mile increase? I know some people here have said no, and to think about more like your gas tank shrinking. So it does not cost the same to "fuel up". I just want to confirm this or hear if someone think otherwise.
No. What happens is the battery reports 'full' sooner than it should. Charging times decrease.

You might end up with more 'call balancing' time, but as power consumption, it's miniscule.

For example if a brand new battery costs $25 to charge to give 500 miles of range, does a 50% degraded battery still cost $25 to charge but only give 250 miles of range? Or is it only going to cost $12.50 and only give 250 miles of range? Essentially meaning the cost per mile cost per mile stays the same.
Yes. Essentially.

The higher impedence/resistance of the battery makes it report 'full' sooner than it should. When you raise those numbers, the apparent voltage drops, but if the battery was 'full' it would sense the same thing. So it's just full, sooner. Like a gas tank with lead weights thrown in it.

2. How does Tesla handle their batter charging? We know full discharging and full charging are bad for the life of the battery. I think each of the car companies handle this problem differently. I believe some manufacturers don't allow the the battery get below a 20% charge or above 80%. They distinguish between gross vs net battery capacity. Effectively 20%-80% is your 0%-100% on your gauge.

I'm under the impression that Tesla does not do this. Tesla allows you to charge to 100% of the gross battery capacity and discharge below 20%, but advise you not to do so. Basically they leave it up to the owner to properly manage their batteries. Is this true or false?
Yes and no. Tesla sells you a range, of which it tries to get you to not use the bottom 30 miles. The actual battery size, though, is whatever they were making at the time - they don't promise you a specific battery (usually).

Which means there are hidden buffers. But don't depend on them.

3. What's worse for the battery; discharging to 0% or charging to 100? From what I have read it seems like the discharging too a very low % is worse for the battery, but then I've also heard the the heat while trying to get that full charge is also bad for the battery. So if I change the numbers a little, what is worse; discharging to 10% or charging to 100% using a Supercharger? An finally what if I discharge to 10% but recharge to 100% at home using a low and slow method?
0 is worse. Lithium batteries are always losing a teeny amount of charge - now a days, it's almost immeasurably small. But it means that charge number is always going down. So a battery left at 0 will kill itself while a battery left at 100% will not.

This depends on chemistry, of course, but if an EV is low on charge, it is essential it gets charged today. If a lithium EV is going to sit, leaving it at 60% is the best.

-Crissa
 

CyberGus

Well-known member
First Name
Gus
Joined
May 22, 2021
Threads
67
Messages
5,807
Reaction score
19,082
Location
Austin, TX
Website
www.timeanddate.com
Vehicles
1981 DeLorean, 2024 Cybertruck
Occupation
IT Specialist
Country flag
Based on Panasonic's ratings of their cells, and Tesla's ratings of their packs, I estimate that Tesla reserves no more than about 10% of the total energy capacity. I can also personally attest that the car can go several miles after the gauge reaches 0% lol.

Here's a technical research report on battery degradation:

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

The TL;DR is: use the middle range of your battery as much as possible. Cycling 100%-80% will degrade far more than 60%-40%. Stay in the middle, and use the margins of the capacity only when absolutely necessary.

Of course, advice varies with chemistry. The LFP pack "likes" to be at 100%, while the Nickel-based version (as the CT will have) will degrade when stored at 100% (even worse at higher ambient temperatures).
 


ajdelange

Well-known member
First Name
A. J.
Joined
Dec 8, 2019
Threads
4
Messages
3,213
Reaction score
3,403
Location
Virginia/Quebec
Vehicles
Tesla X LR+, Lexus SUV, Toyota SR5, Toyota Landcruiser
Occupation
EE (Retired)
Country flag
The tech is getting better but I still have some battery questions.

1. When an battery degrades does the cost per mile increase? I know some people here have said no, and to think about more like your gas tank shrinking. So it does not cost the same to "fuel up". I just want to confirm this or hear if someone think otherwise.
These batteries store energy by using it to pump lithium ions from the cathode to the anode. Another way of storing this energy would be to pump water from one bucket to another at a higher level. Over time some of the water will evaporate and you will be able to store less energy. In the battery some of the lithium ions are lost to parts of the battery other than the cathode and anode. In either case you don't have as much of the storage medium to move and therefore can't store as much energy but it doesn't cost any more energy to move a unit of what is left.


If it is the case that the "tank" gets smaller and the cost per mile stays the same...does the cost per mile really stay the same? I've read that as a battery degrades the impedance of the battery increases. This impedance change would make charging less efficient. So it would actually cost a little more per mile with the degraded battery. Does anyone have any metrics or stats on this? I'm assuming is very slight, but I don't know.
I am sure the impedance curve changes as the battery ages and if it increases of course the heat dissipated in it is going to increase and so the charging losses will increase and, in fact, the cost per coulomb moved will go up. But I also think that the amount of this effect will be small as battery internal impedances are very small.



2. How does Tesla handle their batter charging? We know full discharging and full charging are bad for the life of the battery. I think each of the car companies handle this problem differently. I believe some manufacturers don't allow the the battery get below a 20% charge or above 80%. They distinguish between gross vs net battery capacity. Effectively 20%-80% is your 0%-100% on your gauge.
Only Tesla knows the inner workings of its battery management system. The spec sheet for the 4AH Lishen 2170 battery I posted on this morning shows a fully charged voltage of 4.20V and an end of discharge voltage of 2.75V. We could hook up a voltmeter labeled in % and adjust it such that it read 0% at 3.0V and 100% at 4.0V if we wanted to giving us a buffer at the low end of 0.25V and one at the high end of 0.20V. It's perfectly arbitrary. The various manufacturers do it different ways.


I'm under the impression that Tesla does not do this. Tesla allows you to charge to 100% of the gross battery capacity and discharge below 20%, but advise you not to do so. Basically they leave it up to the owner to properly manage their batteries. Is this true or false?
Darned if I know. One usually finds statements of this sort with statements that Tesla uses this technique to cheat on its EPA consumption tests and it is usually clear that the intent of the people making the statements are not Tesla fans so I have never taken this too seriously,


3. What's worse for the battery; discharging to 0% or charging to 100? From what I have read it seems like the discharging too a very low % is worse for the battery, but then I've also heard the the heat while trying to get that full charge is also bad for the battery. So if I change the numbers a little, what is worse; discharging to 10% or charging to 100% using a Supercharger? An finally what if I discharge to 10% but recharge to 100% at home using a low and slow method?
I'm no battery expert by any means but I have always been led to believe that discharging to a very low voltage is much worse in that it can irreversibly damage the cell. On discharge the cell voltage just goes down and down eventually reaching 0 and, evidently, irreversible chemical reactions take place. At the high end once all the lithium is back in the cathode no further charging can take place and if you raise voltage to force more current all it does is heat the cell. A super charger is, of course, equipped with protective circuitry to prevent cell voltage from ever rising to that point.
 

CyberGus

Well-known member
First Name
Gus
Joined
May 22, 2021
Threads
67
Messages
5,807
Reaction score
19,082
Location
Austin, TX
Website
www.timeanddate.com
Vehicles
1981 DeLorean, 2024 Cybertruck
Occupation
IT Specialist
Country flag
Only Tesla knows the inner workings of its battery management system. The spec sheet for the 4AH Lishen 2170 battery I posted on this morning shows a fully charged voltage of 4.20V and an end of discharge voltage of 2.75V. We could hook up a voltmeter labeled in % and adjust it such that it read 0% at 3.0V and 100% at 4.0V if we wanted to giving us a buffer at the low end of 0.25V and one at the high end of 0.20V. It's perfectly arbitrary. The various manufacturers do it different ways.
This is a good point: a pack at 0% does NOT mean that the cells are at zero volts. Rather, it means the cell voltage has dropped below a certain threshold where there is no useful energy left, and discharging further will only cause damage. The BMS will not allow the pack to be discharged beyond this level. Tesla shuts off the standby function (like Cabin Overheat Protection and Sentry Mode) when the pack capacity is below 20%.

If you actually manage to discharge the cells to 0V, they will be irreparably damaged, but this is nearly impossible to do.
 

Crissa

Well-known member
First Name
Crissa
Joined
Jul 8, 2020
Threads
126
Messages
16,211
Reaction score
27,071
Location
Santa Cruz
Vehicles
2014 Zero S, 2013 Mazda 3
Country flag
Leaving the pack at 0% (why was anyone saying 0v?) runs the risk of the batteries being damaged as they sit.

So many stories of a Zero Motorcycle run to 0, and then left to sit a day or three... and then not coming back to life when finally plugged in. People tend to forget about motorcycles and used cars, so it can and will happen in the future.

Leaving it at 100% will make it less happy in the long run, but it won't kill it in the short one.

-Crissa
 

Crissa

Well-known member
First Name
Crissa
Joined
Jul 8, 2020
Threads
126
Messages
16,211
Reaction score
27,071
Location
Santa Cruz
Vehicles
2014 Zero S, 2013 Mazda 3
Country flag
Oh! And as to heat:

Teslas are thermally managed, both heating and cooling. That saves the battery from the damage of being charged in the cold or hot. Repeated Supercharging (like, many in a day, or during hot weather) of older Teslas did eventually lower total range by a little bit. But just occasional charging did not.

In fact, one study found no difference in range between cars that exclusively used Superchargers for their weekly or biweekly charging compared to home charging over the same mileage.

-Crissa
 


Ogre

Well-known member
First Name
Dennis
Joined
Jul 3, 2021
Threads
164
Messages
10,719
Reaction score
26,998
Location
Ogregon
Vehicles
Model Y
Country flag
The top article seems to refer to a battery designed for power storage rather than vehicles. Long life, but moderate energy density is what you’d want for home power, not a car.
 

Challeco

Well-known member
First Name
Christopher
Joined
Jan 20, 2021
Threads
1
Messages
297
Reaction score
562
Location
Oregon
Vehicles
23ModelY,71F250,14Fusion,66Galaxie
Occupation
Medical Technologist
Country flag
"... I can also personally attest that the car can go several miles after the gauge reaches 0% lol."

I can attest to the learning curve too. 0 on my Model 3 battery meter is not 0 but it is scary to think of the possibility of having a flatbed tow truck pick me up from I-84 and transport me to the "nearest" Tesla shop. That ain't happening.
Sponsored

 
 




Top