Pouch vs Prismatic battery cells - VW announcing their intent to change

Dudd

Well-Known Member
First Name
Richard
Joined
Sep 27, 2020
Threads
2
Messages
138
Reaction score
258
Location
UK
Vehicles
Renault Zoe & Pre-ordered Mach E
Country flag
So, the Mach E uses pouch type battery cells. Recently Volkswagen announced they are moving away from pouch to prismatic cells, like the ones in your phone. I don't know much about such things but after 5 minutes of googling I can't see an advantage to this move other than perhaps cost? Just throwing this out there in case anyone that actually knows anything about this topic wants to comment :)

This article cites safety due to lower energy density: Volkswagen may switch from pouch to prismatic battery cells | Autoblog

Is that really true? I can find other articles saying pouch style is safer because it can expand, so is less likely to explode anyway. Pouch appears to be lighter, smaller and more versatile, so later VW EVs will have bigger and heavier batteries? That is the wrong type of evolution.....

In the meantime I think that leaves me happy with the pouch batteries in the Mach E :)

With regards to energy density they don't seem to factor in the intrinsic dangers of filling ICE vehicles with petrol....
Sponsored

 

malba2366

Well-Known Member
Joined
Dec 7, 2019
Threads
7
Messages
448
Reaction score
427
Location
NY
Vehicles
911 C2S
Country flag
I dunno about the benefits, but the stock market loves it. VW stock up 40% since their battery day event.
 
OP
OP

Dudd

Well-Known Member
First Name
Richard
Joined
Sep 27, 2020
Threads
2
Messages
138
Reaction score
258
Location
UK
Vehicles
Renault Zoe & Pre-ordered Mach E
Country flag
I dunno about the benefits, but the stock market loves it. VW stock up 40% since their battery day event.
I imagine that's because they announced spending a tonne of money on charging infrastructure in US and Europe as well as driving towards future solid state batteries.

The Prismatic battery technology notification does mean they will be targeting cheaper, heavier and less powerful electric cars i.e. much more mainstream than the Mach E, so that would likely have boosted the share price a little too.

I can't see any technical benefits with a prismatic battery that are relevant to a more sporty car like the Mach E. i.e. Bulkier and heavier with lower energy density are a distinct disadvantage in that sort of competition.
 

malba2366

Well-Known Member
Joined
Dec 7, 2019
Threads
7
Messages
448
Reaction score
427
Location
NY
Vehicles
911 C2S
Country flag
I imagine that's because they announced spending a tonne of money on charging infrastructure in US and Europe as well as driving towards future solid state batteries.

The Prismatic battery technology notification does mean they will be targeting cheaper, heavier and less powerful electric cars i.e. much more mainstream than the Mach E, so that would likely have boosted the share price a little too.

I can't see any technical benefits with a prismatic battery that are relevant to a more sporty car like the Mach E. i.e. Bulkier and heavier with lower energy density are a distinct disadvantage in that sort of competition.

Once charging builds out, most EVs in the mainstream price points will have smaller batteries. Only the expensive ones will have the 300+ mile ranges.
 

62Lincoln

Well-Known Member
Joined
Nov 16, 2019
Threads
2
Messages
51
Reaction score
25
Location
Home
Vehicles
2022 GTPE
Country flag
VW announced its plan to build a total of 6 battery cell factories in Europe during this decade with a total output of 240GWh - 2 are already under construction. This assures them of supply for their sales plans (at least in Europe) and also cut out the Korean battery companies (LG and SK) who are warring with one another over patent infringement.

VW spoke of cost reduction, which mirrors malba2366's post above. Quite a bit of the marketplace in Europe are smaller, urban vehicles, so the point about smaller battery footprints for these less expensive vehicles is point on.

The march to solid batteries is continuing, so VW must have an eye towards that technology later this decade.
 


OP
OP

Dudd

Well-Known Member
First Name
Richard
Joined
Sep 27, 2020
Threads
2
Messages
138
Reaction score
258
Location
UK
Vehicles
Renault Zoe & Pre-ordered Mach E
Country flag
So.... all very interesting but my original question was about advantages/disadvantages between prismatic and pouch style batteries...
 
OP
OP

Dudd

Well-Known Member
First Name
Richard
Joined
Sep 27, 2020
Threads
2
Messages
138
Reaction score
258
Location
UK
Vehicles
Renault Zoe & Pre-ordered Mach E
Country flag
As far as I can see none of those links speak to EV applications, commercial advantage to VW with regards to their decision to move to Prismatic and whether there is an advantage other than being able to build cheaper EVs with worse performance characteristics.
 

phidauex

Well-Known Member
First Name
Sam
Joined
Dec 8, 2020
Threads
15
Messages
840
Reaction score
1,545
Location
Colorado
Vehicles
2021 MachE 4EX, 2006 Prius, 1997 Tacoma
Occupation
Renewable Energy Engineer
Country flag
In the stationary storage industry we prefer prismatic cells, because while they may have a tiny bit lower energy density, that doesn't matter much when you are building on a 10 acre site. The plus of prismatic cells is that they hold the electrolyte in with a lot more pressure - the tendency to puff is a problem with pouch cells (not a feature). Cylindrical cells also have a lot of internal pressure, but the round shape means you lose a lot of space around each cell. Prismatic gets you the internal pressure in a pack-able shape.

Over time, that internal pressure helps prevent degradation because the internal cell materials can't expand and contract as much during operation. In the event of a failure, prismatic cells usually have a vent that pops open to release the gas, preventing an explosion.

On EVs, the value of energy density is higher, so the compromise may get tilted more toward the pouch direction again. All features of batteries are compromises - there is no perfect combination right now, you just have to balance, density, cost, longevity and weight and find something that works for your application.
 

CHeil402

Well-Known Member
First Name
Chris
Joined
Sep 21, 2020
Threads
8
Messages
723
Reaction score
1,314
Location
King of Prussia, PA
Vehicles
2017 Audi A4, 2021 MME
Occupation
Electrical Engineer
Country flag
other than being able to build cheaper EVs
What more advantage do you think a company needs than cost? If both options "work" then cost is what matters most. Plenty of superior technologies have died due to cheaper good enough alternatives.
 
OP
OP

Dudd

Well-Known Member
First Name
Richard
Joined
Sep 27, 2020
Threads
2
Messages
138
Reaction score
258
Location
UK
Vehicles
Renault Zoe & Pre-ordered Mach E
Country flag
What more advantage do you think a company needs than cost?
Well, cheap doesn't mean good. Of course there needs to be lots of cheaper more poorly performing cars for the mass market, so I'm sure that cheap will be great for VW who will look to fill that niche. In particular though I was seeking further knowledge to get a better understanding as to whether the pouch style batteries in the Mach E are a disadvantage compared to the Prismatic batteries, but I couldn't see too much evidence in that direction.
 

TheCats

Well-Known Member
Joined
Jan 18, 2021
Threads
0
Messages
95
Reaction score
77
Location
95033
Vehicles
Y5Z
Country flag
It seems counter-intuitive, but cylindrical cells have been the winners for most uses.
They are much easier to build, and result in a longer-lasting pack.

The cylinder (circle) packing density is obviously lower, but at over 90% (0.9069) the impact is lower than most people intuit. And if the voids provide required cooling, the overall density impact is minimal. (This is primarily for large packs. For small cell counts the packing density could be lower, and cooling might not be needed.)

What isn't as obvious is that pouch and prismatic cells tend to have higher edge and corner area. These are problematic for layer alignment during construction, and nonhomogeneous chemistry during use.
 

dbsb3233

Well-Known Member
First Name
TimCO
Joined
Dec 30, 2019
Threads
54
Messages
9,298
Reaction score
10,814
Location
Colorado, USA
Vehicles
2021 Mustang Mach-E FE, 2023 Bronco Sport OB
Occupation
Retired
Country flag
Once charging builds out, most EVs in the mainstream price points will have smaller batteries. Only the expensive ones will have the 300+ mile ranges.
Well, somewhat. Frequent charging is a pretty big negative when trying to drive 600 miles in a day. Plus there's the highway speed penalty. And the cold penalty. And the slow charging in the upper quarter of the battery penalty.

Even in the 300 mile MME, realistic 10-80% range at 75 MPH in 40F temps is closer to 150 miles.

If you drop the starting range to 200, now you're down to around 100 on each road trip leg (beyond the first leg where people usually charge to 100% at home). That's 5 stops of probably 20-40 minutes each in a 600 mile day. Each taking time for a detour off the highway to the charger and back. A lot of people won't put up with that much extra churn time.
 

Sunnyfamilyhomes

New Member
Joined
Oct 26, 2021
Threads
0
Messages
1
Reaction score
0
Location
San Diego
Vehicles
Kia
Country flag
I think the confusion is There are two things going on, not one. First, they are switching chemistries from NMC to LFP. LFP has no cobalt or nickel, just iron, which makes it much cheaper. The tradeoff is that chemistry is about 25% less energy dense right now. For base models that’s what you want, cheaper batteries. The second thing is the cells come in prismatic form, which can be made in larger capacities, upto 300 Ah per cell. This cuts down on integration costs while also getting the longer life with the hard shell for better pressure regulation.
 

ChrisSJR

Well-Known Member
First Name
Chris
Joined
Jun 15, 2021
Threads
0
Messages
121
Reaction score
92
Location
Southern Maryland
Vehicles
2021 MME Space White RWD ER (Spark-E), 2004 Ranger
Occupation
Retired
Country flag
I would think the auto companies and battery makers would factor in the estimated failure rate especially while under warranty since this directly impacts long term costs and customer loyalty.
Sponsored

 
 




Top