Heat Flux Measurements Enable a Fast Alternative to Common Battery Calorimetry

1To increase the safety and quality of batteries, research and data about batteries is necessary. On important parameter is the thermal behavior of batteries, which can be measured with heat flux sensors. In addition to standard calorimetric measurements, using heat flux sensors directly on the battery surface allows for highly resolved thermal profiling at isothermal conditions. Common entropy and enthalpy determination methods take up to 400 hours for characterization of one cell. The entropy profiling with the a heat flux sensor can be done during normal charging and discharging of a battery. With highly sensitive heat flux sensors, calorimetric measurements become affordable and feasible for any system and application. This method opens new dimensions in terms of speed and precision of battery quality and status analysis.

During charging and discharging of batteries Li-ions are intercalated or removed from the electrode. When no more space is available, the Li-ions undergo a phase transition in order to intercalate more ions. The same phase transitions also occur during discharging of the electrode. These transitions are accompanied by thermal energy release or uptake, which can be detected with greenTEG’s heat flux sensors. Any change in the electrode or electrolyte quality can be detected accordingly.

Heat flux sensors can measure conductive, convective and radiative heat fluxes. Tiny piles of serially connected semiconductor material build up a voltage signal as soon as a temperature difference between the two sides of the sensor occurs and thus heat begins to flow. This voltage signal can then be read out and further processed. The advantage of greenTEG’s heat flux sensors is the high sensitivity, which is achieved thanks to a thin sensor module design. A patented production process based on electrochemical deposition allows for highly competitive prices for large volumes.