Toyota's press release had a lot more info than just renewed claims of solid state battery commercialization and a 1000-km range. It's amazing what I can find by actually reading the primary source instead of making jokes based on headlines and journalist publications.
So here’s what Toyota is claiming:
• Again saying solid state batteries are approaching practical application in production BEVs thanks to a “technological breakthrough” solving the durability issue. Aiming for 2027-2028 commercialization in BEVs. We'll see.
• Using a “bipolar” cell design in the future. This is an interesting concept I’ve never seen before. Basically they’re breaking away from the normal method by instead applying anode and cathode materials on opposite sides of common metal foil layers (see figure below). One obvious advantage depicted in the diagram is a reduction in cell casing material, but I don’t know enough about the tech to consider other pros and cons. Toyota touts the potential to substantially improve range, charging speed, energy density and cost for both the high-nickel and iron-phosphate chemistries. Normally, Li-ion batteries use copper foil for the anode and aluminum foil for the cathode, because each is more suitable for the particular chemical and electrical conditions of the anode and cathodes respectively. Toyota did not disclose the current collector material selection, so this remains a mystery for now, but presumably they have come up with some solution because Toyota says the Aqua (also known as Prius c) and Crown hybrid models have already been using this tech. Also, I suspect it will be more challenging to control the internal temperature of this type of cell than conventional cells because the steel containers provide the opportunity to run cooling ribbons along their walls.
I hope we’ll get analysis from The Limiting Factor with some of the battery experts like Dr. Dahn or Dr. Mung opining.
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• Aerodynamic efficiency will be improved with some kind of unspecified hypersonic rocket technology for boundary layer control, developed as a spinoff application from Mitsubishi’s space systems division. Supposedly this can reduce drag coefficient
majorly, with “Cd0.1 level in view”. That’s not a typo; they actually said a drag coefficient (Cd) of 0.1 might be feasible and, for context, the best on the market today are the Lucid Air and Model S at 0.21. This means Toyota is claiming they might achieve literally double the aerodynamic efficiency of the industry state of the art, and this would translate to almost double the highway cruising range (holding battery size, vehicle weight, and cross-sectional area constant for the comparison). Furthermore, Toyota says this improvement is largely independent of the shape of the vehicle, which would be crazy considering that shape is normally the main factor determining Cd and usually it matters more than everything else combined.
It is not at all clear to me how aerospace technology intended for hypersonic flow is applicable to consumer automotive vehicles experiencing incompressible subsonic flow. Hypersonic flow generally has very different physical properties than subsonic flow, especially at the speeds cars move on public highways, which is at most Mach 0.1. However, I’m not an aerodynamics expert and Toyota kept all the details secret. If Toyota and Mitsubishi engineers actually have accomplished this feat and also somehow made it manufacturable and affordable then this will be one of the greatest achievements of all time in the history of automotive technology. On the other hand, this is such an extraordinary boast without any evidence to back it up that I'm very skeptical.
• Gigacastings in the structure. The castings shown in the demo image appear quite primitive compared to Tesla’s castings.
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• Plants will no longer use conveyors and instead use techniques like a “self-propelling assembly line”. Toyota intends to have the cars drive themselves with their own powertrains to move through the production system. "Sensors and control systems on the factory side communicate with wireless terminals mounted on the mass-produced vehicles to control them from the outside. We will aim to integrate the car and the production plant." An advantage will be increasing plant layout flexibility due to not having expensive equipment fixed in place. However, I don't see how this is much of an improvement over Tesla's approach with automated ground vehicles moving around the work-in-progress. One thing to note is that for this to have any meaningful impact, it will require the body-in-white to be mated with the skateboard very early in the build sequence. Toyota calls this "simplified assembly from bottom to top".
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• Digital electronics will be drastically increased in their utilization in the next-gen factory. No specifics provided on what they have in mind, other than vague mentions of having more automated inspection technology.
• Through vertical integration of powertrain components in partnership with suppliers, they have shrunk the size of their "eAxle" powertrain system, which has secondary benefits of enabling increased cabin room and improved aero.
• Switching the inverters to SiC (silicon carbide). If I remember correctly, Tesla had been the only ones in the industry using SiC, but on Investor Day they said Gen 3 will be moving on to cheaper materials to save cost--I think it was just silicon. Toyota claim they and some Tier 1 suppliers have developed some improvements on SiC tech (see report for details). I'm not sure how this stacks up against Tesla's choice.
Overall, Toyota is making some big and (eventually) falsifiable claims, but I think we don't have enough information to properly evaluate their decisions and technology path yet. My first impression is that this is probably a lot of empty hype and lofty promises with overly optimistic commercialization timelines, but with some interesting novel ideas, especially the bipolar battery concept. This will be interesting to watch and I would like to know what you all think.