Fire extinguishing technology has become an important component for addressing battery safety issues. To accelerate the research of fire extinguishing technology for typical power batteries used in electric vehicles and electric aircraft, in this paper, an aqueous vermiculite dispersion (AVD) fire extinguishing agent is used to suppress the thermal runaway (TR) of batteries in various material systems. Two characteristic physical parameters, namely, temperature and flue gas composition, are analyzed and compared in two scenarios (with and without the fire extinguishing agent). Two typical clean fire extinguishing agents (Novec 1230 and 2-BTP) are also applied in the fire extinguishing experiment. The cooling effect of these two extinguishing agents is compared, demonstrating the advantages of the AVD extinguishing agent in terms of extinguishing and cooling.