Exothermic-Based Composite Structures

A thermal battery including: a battery core; and a load-bearing structure at least partially surrounding the battery core. The load-bearing structure including: a plurality of tubes arranged adjacent to one another and connected to at least one adjacent tube of the plurality of tubes; and an exothermic material disposed in the plurality of tubes. The load-bearing structure can include one or more initiation devices for initiating the exothermic material. The plurality of tubes can be compressed in a cross-section to compact the exothermic material disposed on the plurality of tubes. A thermal isolation material can also be disposed at one or more ends of the plurality of tubes.