By coating the iron sulfide cathodes in polymers, a research team was able to create transition-metal sulfide-based lithium batteries with stable cycling and high safety. After 300 cycles, a lithium carbide iron disulfide pouch cell retained 72.0% capacity with no capacity degradation after 100 cycles.
But, do they cause a runaway thermal reaction if pierced?
I demand spicy pillows, not mild ones
If you can cut it in half and it still works I doubt piercing it will do much.