Alternatieve accu cellen

[Jan-Willem Wisselink]

[Discussie over de accu cellen afgeplitst van het "Opium 3.0, OPIUM 4.0 en OPIUM 6.0"-topic. Stromeur]

What kind of chemical composition?

[Ride]

What kind of chemical composition?

https://e2e.ti.com/cfs-file/__key/commu ... 180711.pdf

[Jan-Willem Wisselink]

Ah! Thank you very much; the actual specification of the cell itself! Nice. So it seems you have decided already.

But I was thinking: As you have "plenty" of volume / space for the cells in your design, you could go for a little less capacity and optimize more for cost / safety / lifetime of the battery, by chosing Lithium Iron Phosphate cells. As it is one of the most expensive thing you buy as customer, it is very nice that is has a long lifetime.

Tesla has done this for example on some of their models: https://www.tesla.com/ownersmanual/mode ... FAEF4.html

Section below copied from: https://en.wikipedia.org/wiki/Lithium_i ... te_battery

POSITIVE:
Resource availability
Iron and phosphates are very common in the Earth's crust. LFP contain neither nickel[28] nor cobalt, both of which are supply-constrained and expensive. As with lithium, human rights[29] and environmental[30] concerns have been raised concerning the use of cobalt. Environmental concerns have also been raised regarding the extraction of nickel.[31]

Cost
In 2020, the lowest reported LFP cell prices were $80/kWh (12.5Wh/$) .[32]

Better ageing and cycle-life characteristics
LFP chemistry offers a considerably longer cycle life than other lithium-ion chemistries. Under most conditions it supports more than 3,000 cycles, and under optimal conditions it supports more than 10,000 cycles.
LFP cells experience a slower rate of capacity loss (a.k.a. greater calendar-life) than lithium-ion battery chemistries such as cobalt (LiCoO2) or manganese spinel (LiMn2O4) lithium-ion polymer batteries (LiPo battery) or lithium-ion batteries.[34]

Safety
One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety.[30] LiFePO4 is an intrinsically safer cathode material than LiCoO2 and manganese dioxide spinels through omission of the cobalt, with its negative temperature coefficient of resistance that can encourage thermal runaway. The P–O bond in the (PO4)3−ion is stronger than the Co–O bond in the (CoO2)−ion, so that when abused (short-circuited, overheated, etc.), the oxygen atoms are released more slowly. This stabilization of the redox energies also promotes faster ion migration.[36]
As lithium migrates out of the cathode in a LiCoO2 cell, the CoO2 undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO4 are structurally similar which means that LiFePO4 cells are more structurally stable than LiCoO2 cells.[citation needed]
No lithium remains in the cathode of a fully charged LFP cell. In a LiCoO2 cell, approximately 50% remains. LiFePO4 is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.[17] As a result, LiFePO4 cells are harder to ignite in the event of mishandling (especially during charge). The LiFePO4 battery does not decompose at high temperatures.[30]

NEGATIVE:
Lower energy density
The energy density (energy/volume) of a new LFP battery is some 14% lower than that of a new LiCoO2 battery.[37] Since discharge rate is a percentage of battery capacity, a higher rate can be achieved by using a larger battery (more ampere hours) if low-current batteries must be used. Better yet, a high-current LFP cell (which will have a higher discharge rate than a lead acid or LiCoO2 battery of the same capacity) can be used.

[Ride]

Ah! Thank you very much; the actual specification of the cell itself! Nice. So it seems you have decided already.

But I was thinking: As you have "plenty" of volume / space for the cells in your design, you could go for a little less capacity and optimize more for cost / safety / lifetime of the battery, by chosing Lithium Iron Phosphate cells. As it is one of the most expensive thing you buy as customer, it is very nice that is has a long lifetime.

Tesla has done this for example on some of their models: https://www.tesla.com/ownersmanual/mode ... FAEF4.html

Section below copied from: https://en.wikipedia.org/wiki/Lithium_i ... te_battery

POSITIVE:
Resource availability
Iron and phosphates are very common in the Earth's crust. LFP contain neither nickel[28] nor cobalt, both of which are supply-constrained and expensive. As with lithium, human rights[29] and environmental[30] concerns have been raised concerning the use of cobalt. Environmental concerns have also been raised regarding the extraction of nickel.[31]

Cost
In 2020, the lowest reported LFP cell prices were $80/kWh (12.5Wh/$) .[32]

Better ageing and cycle-life characteristics
LFP chemistry offers a considerably longer cycle life than other lithium-ion chemistries. Under most conditions it supports more than 3,000 cycles, and under optimal conditions it supports more than 10,000 cycles.
LFP cells experience a slower rate of capacity loss (a.k.a. greater calendar-life) than lithium-ion battery chemistries such as cobalt (LiCoO2) or manganese spinel (LiMn2O4) lithium-ion polymer batteries (LiPo battery) or lithium-ion batteries.[34]

Safety
One important advantage over other lithium-ion chemistries is thermal and chemical stability, which improves battery safety.[30] LiFePO4 is an intrinsically safer cathode material than LiCoO2 and manganese dioxide spinels through omission of the cobalt, with its negative temperature coefficient of resistance that can encourage thermal runaway. The P–O bond in the (PO4)3−ion is stronger than the Co–O bond in the (CoO2)−ion, so that when abused (short-circuited, overheated, etc.), the oxygen atoms are released more slowly. This stabilization of the redox energies also promotes faster ion migration.[36]
As lithium migrates out of the cathode in a LiCoO2 cell, the CoO2 undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO4 are structurally similar which means that LiFePO4 cells are more structurally stable than LiCoO2 cells.[citation needed]
No lithium remains in the cathode of a fully charged LFP cell. In a LiCoO2 cell, approximately 50% remains. LiFePO4 is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.[17] As a result, LiFePO4 cells are harder to ignite in the event of mishandling (especially during charge). The LiFePO4 battery does not decompose at high temperatures.[30]

NEGATIVE:
Lower energy density
The energy density (energy/volume) of a new LFP battery is some 14% lower than that of a new LiCoO2 battery.[37] Since discharge rate is a percentage of battery capacity, a higher rate can be achieved by using a larger battery (more ampere hours) if low-current batteries must be used. Better yet, a high-current LFP cell (which will have a higher discharge rate than a lead acid or LiCoO2 battery of the same capacity) can be used.

we have the newest 21700 Samsung cell. I just took this from the internet. can ask manufacturer about current specs

[Jan-Willem Wisselink]

The "newest" is nice. But that doesn't buy me anything

The Samsung INR21700-50E cell has the following chemical compositiom: LiNiMnCo02. In other words: a pretty regular Li-Ion cell.

The one I am suggesting has another chemical composition: Lithium Iron Phosphate (LiFePO4) type. With all associated advantages compared to the previous one.

@Jins: what do you think about my 'brainfart'?

[Ride]

The "newest" is nice. But that doesn't buy me anything

The Samsung INR21700-50E cell has the following chemical compositiom: LiNiMnCo02. In other words: a pretty regular Li-Ion cell.

The one I am suggesting has another chemical composition: Lithium Iron Phosphate (LiFePO4) type. With all associated advantages compared to the previous one.

@Jins: what do you think about my 'brainfart'?

what you mean by longer life in compatison to INR21700-50E?

[FreddyH]

@Jan-Willem Wisselink ik denk dat je in dit verhaal ook moet kijken naar de massa van de accu. Je hebt het erover dat er genoeg ruimte is om cellen met lagere capaciteit te gebruiken, maar dat levert dus meer massa op.

De door @Rideopium genoemde cellen hebben een specifieke energie van zo'n 252 Wh/kg, met 1440 Wh kom je aan op 5,7 kg aan cellen.
Een LiFePO4 cel heeft typisch een specifieke energie van 90 tot 160 Wh/kg, met diezelfde 1440 Wh en hele goede cellen kom je dan op 9 kg aan cellen. Met de 2140 Wh van de long range kom je dan op 8,5 kg vs. 13,4 kg...

Die OPIUMs zijn al niet licht, daar nog eens 3,3 tot 5 kg bij lijkt me geen verstandige keuze.

[Jins]

De LiFePO4 is een ouwe getrouwe cel. Die was er al voor de nu veel toegepaste oplaadbare li-ion. De energie dichtheid heeft in zijn nadeel gespeeld.

Voordeel:
- cycle life (2000 tov 500)
- stabieler: kan je doorboren, zal niet in brand vliegen, diep ontladen en over laden is niet catastrofaal
- grotere laad en ontlaad stromen, geschikt voor snelladen en hoge piekbelasting (accelereren)
- geen milieu belastende grondstoffen, geen grondstoffen met bedenkelijke oorsprong (cobalt mining)

Nadeel:
- lagere cel spanning (3,2V tov 3,7V), je hebt voor een zelfde accuspanning meer cellen in serie nodig —> 48V = 16S ipv 13S en dus een groter volume en hoger gewicht voor een zelfde capaciteit of je moet vrede nemen met een lagere capaciteit

Dat lijken maar 3 cellen maar dat zijn 3 cellen per string. In vergelijk tussen een 13S6P & 16S6P accu zijn dat dus al 18 cellen.

[Jan-Willem Wisselink]

Omdat de capaciteit bij Opium juist zo hoog is, zou ik willen inwisselen voor een cell die langer meegaat. (En daarbij een iets lagere capaciteit op de koop toe nemen)

Wat als je dus de 48v wil behouden en je stopt hetzelfde volume van die 1440Wh vol met LFP cellen? Wat wordt ongeveer de nieuwe capaciteit? En wat is dan (nog) de massa penalty?

[FreddyH]

Gaat niet lukken, de fiets wordt gehomologeerd met 1440 Wh, ze gaan daar niet voor een paar mensen en andere accu instoppen.