NOVELTY - The method involves initiating a core of a thermal battery (100). Temperature of the core corresponding to a portion of material having an exothermic reaction is monitored, where the portion of material is positioned outside the core, and the portion includes fuel and oxidizer mixture. The portion is initiated when temperature of the core falls below a predetermined level. A thermal battery cell of the thermal battery is selected from a list of perchlorates, nitrates, permanganates, fluorinated polymers and metal oxides.    USE - Method for producing power from a thermal battery (claimed) in a munition application e.g. high-G munition application such as non-spinning gun-fired munition and mortar.    ADVANTAGE - The method enables initiating a set of fuel and oxidizer pockets to heat a region of the thermal battery and keep the battery in an activated state, thus increasing runtime of the thermal battery having irregular shape. The method enables readily or closely determining a cooling pattern of multiple thermal batteries of different shapes and different cores of irregular shapes through a widely available computer modeling software and simulation of a transient thermal response, where the cooling pattern can be used to determine an optimal shape of the core, an insulation material and optimal size, shape and distribution of the pockets to achieve maximum battery runtime. The method enables using a layer of insulation material and the pockets of appropriate shapes and sizes to achieve optimal thermal battery performance with better runtime and minimal total size to fit an available space in a munition.    DETAILED DESCRIPTION - The mixture includes multiple silicon nanosponge particles and porous silicon particles. An INDEPENDENT CLAIM is also included for a thermal battery.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a thermal battery.    Thermal battery (100)    Porous silicon-based pyrotechnic material filled compartments (101-104)    Top compartment (105)    Bottom compartment (106)    Initiation devices (111)