Abstract: A battery management system (BMS) to detect conditions favorable to thermal runway. The BMS includes Interdigitated Platinum Electrode (IPE) on a substrate. The IPE contains a coating containing PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate). The system has an impedance measuring system (IMS) to measure impedance changes caused in the IPE due to exposure to volatile organic compounds (VOC's) resulting from decomposition of electrolyte in a battery. The impedance changes are indicative of release of the VOC's from the battery signaling a temperature increase in components of the battery. A method of inferring the concentration of VOC's produced by an electrochemical cell. The method includes providing a sensor integrated into the electrochemical cell, the sensor being IPE on a substrate containing a coating containing PEDOT:PSS, recording the impedance response of the sensor to the VOC's released by the electrochemical cell and inferring the concentration of the VOC's.