It would be effectively impossible to control the manufacture of these batteries. You can make batteries in "R&D quantities" for about $50,000. Alibaba will sell you a full, turnkey "pouch cell assembly line" for about $10,000. More reputable vendors want as little as $15,000.
A pouch cell is composed of layers of "cathode and anode foils between a polymer separator that is folded many times."
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After a machine does this folding, the battery is laminated into a pouch made of aluminum foil, which is then cleaned up, labeled, and flushed into the global supply chain.
To make a battery bomb, you mix PETN "with binders to create a screen-printed sheet" that's folded and inserted into the battery, in such a way as to produce a shaped charge that "concentrat[es] the shock wave in an area, effectively turning the case around the device into a small fragmentation grenade."
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