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My Takeaways from Tesla’s Battery Day event

  1. Tabless architecture cells
  • The new cell will be 46mm in diameter and 80mm in height
  • Laser padded the existing foils to enable dozens of connections into the active material
  • Electron has to travel less distance
  • Better power to weight ratio
  • Tabs slow down rate of production
  • 5x energy, 16% range increase, 6x power

[AG comments]
-> A problem with larger diameter cells is how to get the heat out of the cell’s internals.
-> With the tabless architecture, since there are many connections between the active material and the electrode foils, the internal resistance will be reduced, which also means that the heat generated inside the cell will be reduced.
-> The new tabless architecture also allows better heat flow from the internal of the cell to the external body.
-> Less number of cells in a battery pack simplifies pack manufacturing.
-> Bigger diameter cells will cost less as there is a fixed overhead in manufacturing each cell which will be reduced.
-> Energy density for bigger diameter cell will be higher which translates to higher range, and energy for your battery pack without compromising weight.

2. No slurry – go straight to dry coating

  • Maxwell’s technology improved 4x
  • 10x reduction in factory footprint, 10x reduction in energy use in manufacturing

[AG comments]
-> Here is an article we wrote on the Maxwell dry coated electrode during the acquisition – https://makermax.ca/articles/dry-coated-lithium-ion-tesla-maxwell/
-> Removing the slurry and wet coating step and going to dry coating saves a lot of time, resources and $$ for cell manufacturing

3. High speed continous motion assembly

  • Removing tab in electrode allows for this
  • No start and stop in manufacturing process
  • 7x increase in output per line
  • Grohmann and Hibar acquisitions has helped create unified manufacturing process

[AG comments]
-> Tesla has done this effectively before to scale Model 3 production and its great to see such imporvements in cell manufacturing as well. A lot of companies treat manufacturing as a step-wise process, where each step in almost independent from the previous, Tesla thinks of manufacturing from raw material to product as one big problem to solve instead of many smaller problems. This allows each step to be designed to fit perfectly with the previous one.

4. Formation process

  • Typical factory 25% of the resources
  • 86% reduction in formation investment, 75% reduction in footprint
  • 4x better than current processes

[AG comments]
-> Formation is an important process of cell manufacturing. This is the time the cell receives its first charge and the first time Lithium-ions move from the Cathode to the Anode. Formation equipment is bulky due to the high precision electronics needed to ensure an accurate charge, discharge and measurement of the cell’s vitals. It also needs to be temperature controlled. It is great to see the sort of radical improvement in investment and footprint Tesla was able to achieve by leveraging its current power electronics used in powerwalls and cars.

5. Anode

  • Most abundant in Earth’s crust after oxygen
  • Silicon stores 9x more lithium-ions that graphite
  • Main problem with Silicon is it expands 4x when fully charged. This causes stress inside the cell.
  • Current inventions – SIO, Silicon with carbon and silicon nanowires
  • Tesla silicon invention $1.2 /KWh which is ~10x better than current
  • Ion conducting polymer coating
  • Highly elastic binder

[AG comments]
-> This is revolutionary and I need to do more research on it before commenting. Silicon will provide a cost reduction to the anode and can intercalate more Lithium-ions, so this is definitely a huge improvement for the long term cost reduction of cells and battery technology.

6. Cathode

  • Bookshelves analogy
  • Need stable structure to contain the ions
  • Increase Nickel content
  • Cobalt is a stable bookshelf
  • Nickel manganese
  • Nickel 50-60% better than iron
  • 2/3 Nickel 1/3 Manganese
  • 15% reduction in cathode $ / KWh

[AG comments]
-> Intercalation is important for a Lithium-ion cell to charge and discharge. It is also important that during the intercalation process, the Lithium-ions should be able to house themselves without mechanically or chemically altering the cathode. Cobalt is referred to as a stable bookshelf as it allows for lots of Lithium-ions to house themselves in the crystalline structure of Colbalt again and again which allows for high energy density and a long cycle life. Cobalt is however expensive, and therefore the move is towards increasing Nickel content without compromising the energy density and stability.
-> The goal is definitely to move towards zero Cobalt in batteries and Tesla has been making progress on this for many years. Cathodes in the coming years will see a combination of iron, nickel or manganese based on the desired application. For some applications, a 100% nickel cathode may also be considered.

7. Cathode process improvements

Current

  • metal to metal sulphate
  • add chem, add water
  • too much waste

New

  • metal + water
  • Sulphate free process
  • 66% reduction in capex, -76% in process cost, zero waste water
  • using table salt to extract Lithium from its ore!

[AG comments]
Tesla is working towards simplifying the cathode production process by removing intermediary steps. This is Tesla’s first pricinipals engineering approach at best. I need to do more research to understand how the new cathode production process is accomplished.

8. Recycling providing raw materials after steady state is achieved

  • The recycling processes will provide the raw materials for new cells to be manufactured once the number of electric cars on the road has achieved high numbers and there is a steady influx of old cars that are coming in to the recycling plant.

[AG comments]
This step really completes the cycle of sustainability as when this is achieved, the dependence on mining will be minimized!

9. Battery provides structural support to car

  • Non cell portion of battery pack has negative mass
  • Currently 3 and Y filler is structurally adhesive and flame retardant which allows for sheer transfer
  • Cells closer to the center of the car in new design
  • Reduces possibility of side impacting penetrating the cells
  • Better manuvering for the car
  • 10% mass reduction

[AG comments]
This is incredible engineering. Tesla is not treating the battery pack as a weight / baggage to carry around in order to run the car. The battery pack is integral to the structure of the car and the hard cell casings provide the sheer stress support as well.

In the Battery Masterclass (https://makermax.ca/bms), we talk about how the hard cell casing of cylindrical and prismatic cells reduces energy density because of the weight of its casing, but Tesla has turned this around to its advantage by using that external cell casing and making it integral to the mechanical strucuture of the pack.

Overall
54% increase in range
56% reduction in $/kWh
69.420% reduction in investment per GWh
= $25,000 passenger car!

[AG comments]
It’s absolutely amazing to see the innovative engineering work being done at Tesla. Instead of taking the currently available technology for what it is, they are working on reinventing each and every step of the process to be as efficient as possible and turning limitations into advantages. I look forward to hearing your comments as well and researching more on the topics discussed in detail, as this is simply ground-breaking.

2 Responses
  1. Sushanto Mukherjee

    Hi Alshay, I have recently read about Spinel and olivine geometries which can eliminate here’s my points:

    Spinel cathodes
    In 1983, Goodenough and Thackery proposed LixMn2O4.(LMO) as an alternate intercalation material: Mn sits in the octahedral sites, Li in the tetrahedral This material has a cubic “spinel” structure. It allows 3D
    diffusion (vs. 2D for layered and 1D for olivine) .Value of “x” typically varies between 0. . . 1, but can go as
    high as 2 (LMO unstable in acidic conditions when x ) LMO is cheaper and safer than LCO, but can have short lifetime due to the manganese dissolving into the electrolyte under some conditions.

    Olivine cathodes
    In 1997, Goodenough proposed olivine-style phosphates as a third major category of positive-electrode material LixFePO4 (LFP) is the most common in this family.This material is low cost, and low toxicity, but also has low energy density due to a low open-circuit potential and low
    specific energy due to heaviness of Fe.1D structure tends to have high resistance, which can be
    overcome in part by using very small particles and including conductive additives.
    Recently, Chinese company BYD also described its plan to remove cobalt from negative electrodes as cobalt mining is violating human rights of netizens of republic of congo.

  2. Akshay Shinde

    Hi Akshay,
    Thanks a lot for these detailed takeaways from the Tesla’s Battery Day event. Tesla’s approach of deconstructing and engineering from the ground up is really inspiring and that’s how automotive industry should be operating but unfortunately it has lost its way especially the big 3 OEM’s.
    Would love to hear your research on the revolutionary silicon in anode breakthrough and how are they tackling the expansion issue.
    Please keep up your good work of spreading your valuable knowledge!

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