Capsules, heat-not-burn (HNB) aerosol-generating devices, and methods of generating an aerosol

A capsule for an aerosol-generating device, comprising:

• a base of a thermally-conductive material, the base defining a first cavity therein, the base including a first surface, the first surface defining an opening to a second cavity, the first surface including a first plurality of apertures through the first surface, the first plurality of apertures being around the opening to the second cavity, the second cavity being annular and the first cavity surrounding the second cavity;
• and
• a cover coupled to the base and on the base, the cover including a second plurality of apertures in a middle portion of the cover, the first plurality of apertures and the second plurality of apertures defining an air flow path through the base and the cover;
• wherein the second cavity is configured to receive a heating system configured to heat the base.