Primary cells (8506) are designed for single use and cannot be recharged; once discharged, they are spent. Storage batteries (8507) are designed to be recharged repeatedly. The distinction is the electrochemical design intent, not the physical form factor — a lithium coin cell intended for single use is 8506, while a lithium-ion cell designed for cycling is 8507.

Yes. Lithium primary batteries are classified as dangerous goods under IATA and IMDG regulations, requiring proper UN number marking, state-of-charge limits, and packaging certifications. While these are transport requirements rather than US customs admissibility rules, non-compliant shipments can be refused by carriers or detained at the port. Importers should coordinate with freight forwarders experienced in dangerous-goods handling.