Provided is a battery cooling and fire protection system, comprising: (A) a plurality of battery cells, wherein at least a cell comprises an anode, a cathode, an electrolyte, a protective housing that at least partially encloses the anode, the cathode and the electrolyte, and at least one heat spreader element disposed partially or entirely inside the protective housing; and (B) a case configured to hold the plurality of battery cells and a cooling liquid, wherein the battery cells are partially or fully submerged in the cooling liquid, which is configured to be in thermal communication with the heat spreader element and is configured to transport heat generated by the battery cells through the heat spreader element to the cooling liquid and wherein the cooling liquid comprises a fire protection or fire suppression substance.