The liquid cooling system for lithium iron phosphate battery modules usually faces the threat of coolant leakage, which would dramatically affect the heat transfer performance, safety, and efficiency of the energy storage system. Herein, electrochemical sensing technology has been first employed to detect coolant leakage. Specifically, ethanol is selected as the additive reagent and used as the main tested substance, and the sensors indirectly identify the coolant leakage by detecting the leaked ethanol. In order to overcome the disadvantages of pure SnO