The Tesla battery fuse system provides protection against thermal runaway that is not available in prismatic slab/brick configurations such as in the Chevrolet Bolt.
A prismatic slab can be considered to be like a cylinder cell except unwrapped into a flat plate, with a single Tesla cell representing perhaps 1/20th to 1/40th of the stored capacity of the slab.
Cell failures are triggered by the formation of solid crystal lattices within the chemicals that make up battery systems.
Crystal formation has negatively impacted the lifespan and usability of virtually every kind of rechargeable battery chemistry, including nickel-cadmium, lead-acid, and now lithium polymer batteries.
The one type that is not affected is called the flow battery, whereby solidified crystals can be actively sifted out of the liquid chemicals circulated through the flow battery.
The high concentration of specialized chemicals makes it very easy for crystals to form within rechargeable batteries, and a large amount of the technical, chemical, and mechanical design of batteries involves making the device resistant to the formation of crystals.
The risk of crystal formation is the highest when the battery is either deeply discharged or fully charged, and also when the the battery is very hot. This is why batteries are commonly only operated in a range of 20% discharged to 80% charged, and cooling is needed to prolong the life of the cells.
Once crystals form, the chemicals typically do not dissolve, so cell storage chemistry is permanently lost. Also, crystalline structures will grow over time, and can exert physical pressure on the internal components of the battery. They are also electrically conductive.
Cell failure is the result of a crystal forming which has grown large enough to span the gap between the anode and the cathode. The body of the crystal triggers an electrical short between the plates that cannot be otherwise broken or removed inside the cell.
Tesla battery fuses provide a way to disable shorted cells and remove them from the parallel battery group.
Even if thermal runaway does not occur, the shorted cell permanently reduces the total maximum charging capacity of the overall battery module.
The rest of the cells in parallel with the failed cell can no longer hold a charge, reducing the total pack voltage.
This shorting protection is not available within a solid uniformly constructed prismatic battery brick.
Currently there is no way to stop runaway cell discharge from the entire rest of the prismatic brick through a shorting crystal somewhere within the prismatic brick.
Protection is possible but would require a redesign of the prismatic brick by cutting it into very thin cross-sections, each representing the typical cell capacity of a Telsa cylinder battery.
Each cross-sectional cut through the slab is then insulated from each other within the overall slab structure, and fuses are installed on each small fractional chunk of the overall slab.
Structurally this may have the appearance of 20-40 pouch batteries placed side by side within the space previously occupied by the large unified prismatic slab.
This reduces the manufacturing efficiencies of being able to produce a single unified slab rather than needing to make hundreds of individual pouches, but provides better protection against thermal runaway and permanent discharge if any one of the small pouch prismatic batteries becomes internally shorted.