Thomas Yersak | General Motors Global R&D Center: What happens when a highly engineered solid-state component is too difficult to manufacture at scale?
00:09:25.805 - 00:12:04.205
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Summary of the clip:
What happens when a highly engineered solid-state component is too difficult to manufacture at scale?
This clip details GM's "almost solid" Gen 1 approach for lithium-sulfur batteries, which centered on a highly engineered, impermeable solid electrolyte separator. The goal was to block the polysulfide shuttle effect that plagues Li-S cells. Yersak explains the material science challenge of finding a sulfide-based material that is chemically stable against the liquid electrolyte and developing a scalable process—slip casting a green tape followed by hot pressing a glass-ceramic—to create a dense, ionically conductive separator.
Despite achieving promising results, including an ionic conductivity of 1 mS/cm and demonstrating function in cells, the Gen 1 design was ultimately deemed a "science project" and not commercialized. The critical failure point was not performance, but manufacturing yield. The immense difficulty of producing large, defect-free ceramic separators at scale meant the technology was not viable for a high-volume product, as "if you don't have yield, you don't have a cell design."
This roadblock forced a strategic pivot to a more pragmatic "semi-solid" Gen 2 design. Instead of relying on a complex and expensive separator, the new approach uses the solid electrolyte as a simple powder additive mixed directly into the cathode. This shift dramatically simplifies manufacturing and aligns with the core goal of getting the "biggest bang for your buck with the least amount of headache," showcasing a real-world example of R&D adapting to manufacturing reality.
In this short video, you can learn:
* The design and processing of a glass-ceramic sulfide separator for a hybrid Li-S battery.
* Why low manufacturing yield and defects can kill a promising battery design.
* The strategic pivot from a complex solid separator ("almost solid") to a simple powder additive ("semi-solid").
📋 **Clip Abstract** This clip follows a real-world R&D journey from a complex "almost solid" battery design to a more pragmatic "semi-solid" approach. It highlights how manufacturing challenges, specifically low yield on a solid-state separator, forced a pivot to a simpler design using a solid electrolyte powder as a cathode additive.
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#LithiumSulfur, #SolidElectrolyteSeparator, #CeramicProcessing, #CathodeAdditive, #SolidStateBattery, #BeyondLithiumIon
This is a highlight of the presentation:
Solid-State Electrolytes for Lithium Sulfur Batteries
More Highlights from the same talk.
00:03:13.195 - 00:04:48.205
Are "all-solid-state" batteries truly non-flammable?
Are "all-solid-state" batteries truly non-flammable?
While all-solid-state batteries (ASSBs) offer a significant safety improvement over conventional liquid electrolyte cells, they are not immune to thermal runaway. Thomas Yersak shares data from Accelerated Rate Calorimetry (ARC) testing on GM's sulfide-based ASSB. While a conventional cell might enter thermal runaway at 160°C, their solid-state cell is stable up to 225°C, demonstrating a clear safety benefit but not complete immunity to failure under extreme abuse conditions.
The presentation debunks the common myth that solid-state means non-flammable by explaining the underlying failure mechanism. Sulfide-based solid electrolytes are themselves flammable solids. When heated in air, they decompose and release sulfur gas, which can auto-ignite and produce a flame. This is a critical piece of information often overlooked in the hype surrounding solid-state technology.
Yersak reveals a specific thermal runaway mechanism involving the chemical reaction between the high-nickel NCM cathode active material and the sulfide solid electrolyte. This reaction is a key driver of the thermal event. Despite this, he emphasizes that these cells are still fundamentally safer than their liquid-based counterparts, and active research is focused on developing less flammable solid electrolyte compositions to further improve safety.
In this short video, you can learn:
* Why sulfide-based all-solid-state batteries can still undergo thermal runaway.
* The specific thermal runaway mechanism involving high-nickel cathodes.
* How heating sulfide electrolytes in air can lead to auto-ignition of sulfur gas.
📋 **Clip Abstract** Contrary to popular belief, all-solid-state batteries using sulfide electrolytes and high-nickel cathodes are not inherently non-flammable. This clip explains the specific chemical mechanism behind their thermal runaway, providing a crucial reality check on solid-state battery safety.
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#SulfideASSB, #ThermalRunaway, #SulfideElectrolyte, #HighNickelCathode, #AllSolidState, #BatterySafety
00:05:00.545 - 00:06:17.405
If a solid-state battery is safer, how much more is an automaker willing to pay for it?
If a solid-state battery is safer, how much more is an automaker willing to pay for it?
From an automotive OEM's perspective, safety is a fundamental expectation, not a premium feature that customers are willing to pay extra for. Therefore, the higher cost of an advanced, safer battery technology like solid-state must be justified by cost reductions at the battery pack system level. This clip provides a pragmatic analysis of the true economic value of improved cell safety.
The analysis explores what pack-level components could be simplified or eliminated if the cells were inherently safe. These components include thermal runaway barriers—insulating pads placed between cells to prevent propagation—and potentially less complex cooling systems. By removing these parts, an automaker can save on material cost, weight, and assembly complexity, which could offset a more expensive cell.
However, the conclusion is stark: the total cost savings from eliminating these safety components are surprisingly small, justifying only a single-digit percentage increase in cell cost. This slim margin is often completely overshadowed by the new system-level costs that solid-state batteries introduce. These include the need for complex mechanical structures to apply high stack pressure, systems for elevated temperature operation, and entirely different pack designs to accommodate swelling or new cell formats.
In this short video, you can learn:
* Why customers won't pay a premium for safer batteries.
* How cell safety translates to battery pack system-level costs.
* The limited cost increase (single-digit percent) that can be justified by removing pack-level safety components.
📋 **Clip Abstract** This clip provides a critical automotive OEM perspective on the economic value of safer batteries. It reveals that the system-level cost savings from eliminating components like thermal barriers are minimal, posing a major challenge to the business case for expensive solid-state cells.
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#ThermalRunawayBarriers, #BatteryPackIntegration, #CellSafetyEconomics, #SolidStatePackChallenges, #SolidState, #EVBatteryTechnology