Battery development is done in 4 major sample stages: A thru D Samples. I’ll cover them briefly here, but for more detail check out BetteryDesign.net.
A Sample ✔️
The A Sample is prototype everything. The cell is a prototype design, likely not even having the performance characteristics of the final product (in fact, I estimated that A0 cells sent out by QS in 2022 were less than 400 wh/L, less than half their design goal). The tooling and manufacturing processes are low batch, and non-scalable.
This is just to show auto OEM’s that they have a proof of concept, essentially.
QS has cleared A sample development. VW has publicly validated the testing of A sample cells. Here’s are a couple of quotes from VW’s press release in early 2024:
The U.S. company QuantumScape has recently reached an important milestone, which was now confirmed by PowerCo: its solid-state cell has significantly exceeded the requirements in the A-sample test and successfully completed more than 1,000 charging cycles. For an electric car with a WLTP range of 500-600 kilometres, this corresponds to a total mileage of more than half a million kilometres. At the same time, the cell barely aged and still had 95 percent of its capacity
AND
PowerCo CEO Frank Blome: "These are very encouraging results that impressively underpin the potential of the solid-state cell. The final result of this development could be a battery cell that enables long ranges, can be charged super-quickly and practically does not age. We are convinced of the solid-state cell and are continuing to work at full speed with our partner QuantumScape towards series production."
B Sample (in-work)
The design of the cell is frozen, meaning there will be no changes to chemistry or physical design going forward. The prototype line using production tooling has proven that the cells can be made to all of the process parameters.
As implied above, the B Sample should be essentially the commercial product, made on near final design production tooling. Figure 2 compares QS’s A and B sample.
The production portion of this stage is very important. A Samples were produced on Quantumscape’s Phase II Engineering Line. We don’t have a ton of details on the processes that were used here, but we can imagine that much of it used batch processing (rather than continuously flow) and a lot of manual assembly of cells. In order to advance towards commercialization, QS will need to implement more and more automation. B samples will be built on higher throughput lines, monikered Raptor and Cobra.
Raptor is the first generation of Quantumscape’s “fast” production line. It stands to offer throughput of nearly 3x more than the Phase II Engineering Line. Initial “low production” B Sample (B0) cells will be produced on this line - projected for the 2nd half of 2024.
Cobra will be the follow on to Raptor. This will implement the full potential of their new heat treatment process for producing their ceramic separator. Throughput gains will be roughly 4x over Raptor (reaching 100,000 separators produced per week).
100,000 film starts per week (fspw) supports 4 - 5 MWh of annual production; enough for 40 - 50 vehicles annually (assuming 100 kwh packs). This implies that 200 Cobra machines are needed to produce enough separators to support 1 GWh of production (or 10,000 vehicles). This iteration of Cobra is a far cry from mass commercial scale, but certainly a step in the right direction.
During this time, QS and OEM partners should be working in tandem towards pack and module integration of their cells. B samples from Cobra should go into test vehicles by early / mid 2026.
C Sample (?)
The cell design, sourcing of sub-components and all materials is fixed. The production line and tooling is all complete. The production line is now used to confirm the control requirements as it is brought up to run at full rate with cells made in batches.
This is a very expensive part of production where the control parameters are stabilized and proven to produce quality cells at rate. This process can take many months.
Performance, lifetime and safety testing will be re-run as an over-check against the B Sample cell data. No differences in results are to be expected.
In addition, C Samples are official commercial grade cells that can be sold to OEMs for vehicles available to the general public.
This is where the future gets a little murky for Quantumscape as they’ve provided no guidance beyond Cobra B samples in 2025.
Management has stated that GWh scale will come on the back of larger Cobra designs.
It stands to reason that the original Cobra line in the QS-0 plant should be capable of producing cells for official commercial use by OEMs after being cleared of B Samples stage. In addition, Cobra lines have shown to have a relatively small footprint. Several Cobra lines could be installed in QS-0 as a means of quick horizontal scaling. As mentioned previously, Cobra will support approximately 50 vehicles per line. Setting up 10 lines would yield enough for 500 cars. Depending on how quickly it is to stand up a Cobra line, this may be a path forward for series production for an ultra-premium vehicle.
In conjunction, I imagine that larger Cobra tooling will be designed and prepped for QS-1 as part of the Joint Venture with Volkswagen (location and other details yet to be disclosed). My guess is that QS-0 will also get its own large Cobra line.
Again, this is highly speculative. VW may want to see proof that Cobra scales prior to committing to scaled installation. But I think there’s an argument to the contrary as well. QS-1 Phase I (1 GWh of production) is monikered as a pilot line. So it’s possible that VW may be willing endure some expected growing pains and R&D work attributed to this prior to scaling to Phase II (20 GWh).
I anticipate QS sharing guidance on these next steps some time in the back half of 2025 (assuming Cobra progresses as planned).
D Sample (?)
The production line is running in control and at rate.
Any changes to chemistry, supply, material pre-processing or production process will reset the cell back to B Sample status and require re-qualification.
From what I understand from batterydesign.net, at this phase, everything about the production process and materials sourcing is locked in. The manufacturing line should be completely set up, locked in, and running at full capacity. No changes to the design or bill of materials will be made without a more official revision sign-off process, and re-validation of the cells.
I’ll probably update this when we get more details from QS in the future.