Class D fire extinguishers are for extinguishing flammable metal fires, involving e.g. lithium, magnesium, titanium, aluminum, and so on. Disposable (primary) l

Class D fire extinguishers are for extinguishing flammable metal fires, involving e.g. lithium, magnesium, titanium, aluminum, and so on. Disposable (primary) lithium batteries contain metallic lithium that can ignite. Lithium ion batteries contain lithium in an ionic (non-metallic) form. Lithium ion batteries contain flammable electrolytes and polymers, so they can burn, but these are not metal fires calling for a Class D fire extinguisher.