I'm using this post/thread to summarize all the improvements Tesla announced on Battery Day to get to a total 56% $/Kwh reduction. You can watch the full Tesla video at the link at the bottom.
1. Cell Design - Tabless Cell
From a 21mm x 70mm size to a 46mm x 80mm
This gives them an immediate 17% cost reduction just from the bigger size, and a 7% energy density improvement. But they couldn't have built this bigger cell without some sort of heat dissipation improvement since the bigger cell would have heated up too quickly and reduced total power output (meaning much slower super charging times).
The tabless cell is what gives them a huge improvement in heat dissipation. Electrical path length goes from 250mm to 50mm even though the cell is much bigger. While they showed a picture of a tabless cell top, there was much they didn't show or explain.
End result is that the bigger tabless cell gives you 4x energy, +16% range, and 6x power of the 2170. However note that this new cell is 5.4x the volume of the old 2170, so what is really going on here? Why only 4x the energy, not 5.4x the energy? They ended up with a lower volumetric or gravimetric (which one wasn't stated) energy density? This might have to do with further below when Elon said the casing was now steel rather than aluminum. They most likely used steel because it is now a structural element (see last section).
The summary chart on this innovation shows a 14% overall $/kWh reduction.
2. Factory - Process and Machine Innovations
The big one here is the dry electrode process they got from Maxwell (and have been refining ever since). 10x reduction in footprint, 10x reduction in energy use. Close to working. Works at low yield, needs more machine designs to get high yield.
They increased line efficiency to get 7x output per line.
Cell formation improvements. Sounds like instead of charging each cell individually, they do them in batches plus other innovations. Ends up with an 86% reduction in formation equipment investment and a 75% formation footprint reduction.
Overall these factory improvements give you 75% investment reduction per GWh and a 10x smaller footprint per GWh.
So, on a battery pack basis, this results in a 18% $/kWh reduction.
3. Silicon Anode
Silicon is cheaper than highly processed graphite, and can have a theoretical 10x increase in energy density.
There are three known industry methods to get silicon into the anode. Silicon structured in SIO glass which they said costs $6.6/kWh for the anode. Silicon structured in graphite, costing $10.2/kWh, and Silicon nanowires, costing more than $100/kWh.
So Tesla came up with their own idea which only costs $1.2/kWh. Use raw silicon metal, powder it, encase it in an ion conducting polymer and use a highly elastic binder to account for its expansion when being charged.
This ends up giving you 20% longer range and it is cheaper than what Tesla currently uses. So, far cry from a theoretical 10x energy density improvement, but you still get a bump up from current anodes AND it is cheaper. In the end, Tesla cut through the BS, didn't go for the holy grail for silicon anodes, and went with a good enough improvement over what they have now. Classic Tesla.
OK, so this ends up giving you a 5% overall cost reduction in terms of battery pack $/kWh reduction.
4. Cathode
Tesla has made a cobalt free, high nickel cathode using novel coatings and dopants that gives you a 15% reduction in cathode $/kWh (since cobalt is much more expensive than nickel and the other ingredients).
They also going to use three different kinds of cathodes.
Iron based cathodes for stationary storage and cheaper or low range cars. Nickel + Manganese (2/3 nickel, 1/3 manganese) for long range cars, and high nickel for long range mass sensitive vehicles like the Cybertruck and the Semi.
FYI, a pure nickel cathode versus iron cathode, nickel is 100% better (2x) than iron, but at the pack level, it is only 50% to 60% better.
Cathode process improvements. Instead of using metal sulfates from the mines, they are getting raw metal now. That alone gives them a 66% reduction in investment, 76% reduction in process cost.
For lithium (also part of the cathode), they will again skip the sulfate process step, and use their own processing to take raw lithium ore, process it the way they want to extract the lithium metal. This will results in a 33% reduction in lithium cost. This is a Tesla invented process that uses sodium chloride (ie table salt) to extract lithium from the ore. Wow.
Also, they obtained mineral rights for a 10,000 acre lithium clay deposit in Nevada. Tesla will mine their own lithium.
All this results in a 12% $/kWh reduction.
5. Using cells as a structural element
Use a single piece casting for front body and a single piece for rear body. Had to create own aluminum alloy for this. The reason for this (other than cost) is that they can now use the battery cells themselves as a structural element. Current battery uses a filler between cells that is a flame retardant. New battery architecture uses a filler than is a structural adhesive as well as a flame retardant. This glues the cell to the top and bottom sheets and allows for sheer force transfer. Ends up with a very stiff structure - stiffer than what they have now, which will be nice for driving dynamics. Elon used the word "steel shell case" to describe the cells, so I guess they use steel (as opposed to lighter aluminum) as the casing material for structural reasons.
You end up with three body pieces. A front casting, a rear casting and joining them together is the battery case structure (which is also mostly a casting).
Bottom line is that these innovations give you 10% mass reduction, 14% range increase "opportunity", and 370(!) fewer parts.
So this innovation will result in 7% in a total battery pack cost $/kWh reduction.
Add all those together to get a 56% battery cost $/kWh reduction, which is HUGE.
Finally, note that Elon said there were other improvements that they didn't discuss as well as details that they are keeping under wraps ("secret sauce").
It'll be probably three years to fully realize all these cost savings. Will start using these savings in 1.5 years.
1. Cell Design - Tabless Cell
From a 21mm x 70mm size to a 46mm x 80mm
This gives them an immediate 17% cost reduction just from the bigger size, and a 7% energy density improvement. But they couldn't have built this bigger cell without some sort of heat dissipation improvement since the bigger cell would have heated up too quickly and reduced total power output (meaning much slower super charging times).
The tabless cell is what gives them a huge improvement in heat dissipation. Electrical path length goes from 250mm to 50mm even though the cell is much bigger. While they showed a picture of a tabless cell top, there was much they didn't show or explain.
End result is that the bigger tabless cell gives you 4x energy, +16% range, and 6x power of the 2170. However note that this new cell is 5.4x the volume of the old 2170, so what is really going on here? Why only 4x the energy, not 5.4x the energy? They ended up with a lower volumetric or gravimetric (which one wasn't stated) energy density? This might have to do with further below when Elon said the casing was now steel rather than aluminum. They most likely used steel because it is now a structural element (see last section).
The summary chart on this innovation shows a 14% overall $/kWh reduction.
2. Factory - Process and Machine Innovations
The big one here is the dry electrode process they got from Maxwell (and have been refining ever since). 10x reduction in footprint, 10x reduction in energy use. Close to working. Works at low yield, needs more machine designs to get high yield.
They increased line efficiency to get 7x output per line.
Cell formation improvements. Sounds like instead of charging each cell individually, they do them in batches plus other innovations. Ends up with an 86% reduction in formation equipment investment and a 75% formation footprint reduction.
Overall these factory improvements give you 75% investment reduction per GWh and a 10x smaller footprint per GWh.
So, on a battery pack basis, this results in a 18% $/kWh reduction.
3. Silicon Anode
Silicon is cheaper than highly processed graphite, and can have a theoretical 10x increase in energy density.
There are three known industry methods to get silicon into the anode. Silicon structured in SIO glass which they said costs $6.6/kWh for the anode. Silicon structured in graphite, costing $10.2/kWh, and Silicon nanowires, costing more than $100/kWh.
So Tesla came up with their own idea which only costs $1.2/kWh. Use raw silicon metal, powder it, encase it in an ion conducting polymer and use a highly elastic binder to account for its expansion when being charged.
This ends up giving you 20% longer range and it is cheaper than what Tesla currently uses. So, far cry from a theoretical 10x energy density improvement, but you still get a bump up from current anodes AND it is cheaper. In the end, Tesla cut through the BS, didn't go for the holy grail for silicon anodes, and went with a good enough improvement over what they have now. Classic Tesla.
OK, so this ends up giving you a 5% overall cost reduction in terms of battery pack $/kWh reduction.
4. Cathode
Tesla has made a cobalt free, high nickel cathode using novel coatings and dopants that gives you a 15% reduction in cathode $/kWh (since cobalt is much more expensive than nickel and the other ingredients).
They also going to use three different kinds of cathodes.
Iron based cathodes for stationary storage and cheaper or low range cars. Nickel + Manganese (2/3 nickel, 1/3 manganese) for long range cars, and high nickel for long range mass sensitive vehicles like the Cybertruck and the Semi.
FYI, a pure nickel cathode versus iron cathode, nickel is 100% better (2x) than iron, but at the pack level, it is only 50% to 60% better.
Cathode process improvements. Instead of using metal sulfates from the mines, they are getting raw metal now. That alone gives them a 66% reduction in investment, 76% reduction in process cost.
For lithium (also part of the cathode), they will again skip the sulfate process step, and use their own processing to take raw lithium ore, process it the way they want to extract the lithium metal. This will results in a 33% reduction in lithium cost. This is a Tesla invented process that uses sodium chloride (ie table salt) to extract lithium from the ore. Wow.
Also, they obtained mineral rights for a 10,000 acre lithium clay deposit in Nevada. Tesla will mine their own lithium.
All this results in a 12% $/kWh reduction.
5. Using cells as a structural element
Use a single piece casting for front body and a single piece for rear body. Had to create own aluminum alloy for this. The reason for this (other than cost) is that they can now use the battery cells themselves as a structural element. Current battery uses a filler between cells that is a flame retardant. New battery architecture uses a filler than is a structural adhesive as well as a flame retardant. This glues the cell to the top and bottom sheets and allows for sheer force transfer. Ends up with a very stiff structure - stiffer than what they have now, which will be nice for driving dynamics. Elon used the word "steel shell case" to describe the cells, so I guess they use steel (as opposed to lighter aluminum) as the casing material for structural reasons.
You end up with three body pieces. A front casting, a rear casting and joining them together is the battery case structure (which is also mostly a casting).
Bottom line is that these innovations give you 10% mass reduction, 14% range increase "opportunity", and 370(!) fewer parts.
So this innovation will result in 7% in a total battery pack cost $/kWh reduction.
Add all those together to get a 56% battery cost $/kWh reduction, which is HUGE.
Finally, note that Elon said there were other improvements that they didn't discuss as well as details that they are keeping under wraps ("secret sauce").
It'll be probably three years to fully realize all these cost savings. Will start using these savings in 1.5 years.
