A convenient convective type dimensionless lumped-capacitance (DLC) method for battery heat generation measurement is proposed. The effective heat transfer coefficient and heat generation can be obtained simultaneously, and no prior calibration of the equipment is needed. The new dimensionless method is verified by reference sample, and the experimental results agree with the theoretical line. The heat generated by a lithium thionyl chloride (Li/SOCl 2 ) battery is measured at the ambient temperature range of 38 • C to 50 • C. Results reveal that the heat generation is not influenced by ambient temperature at a small discharge current, and the heat generation increases at higher ambient temperature under a higher discharge current condition. The heat generation is approximately proportional to the discharge current in the range of 1.0 A to 5.0 A. The heat generation measurement method can be extended to obtain the heat generated by other types of battery.With their high energy density and high power density, lithium thionyl chloride (Li/SOCl 2 ) batteries are used in navigation equipment and spaceflight applications. However, the application of Li/SOCl 2 batteries is limited by safety incidents such as fire and explosions. 1,2 A recently reported safety incident in January 2013 was the grounding of a Boeing 787 Dreamliner, which was attributed to a fire started by the short circuiting and thermal runway of lithium batteries. 3,4 Thermal management is one of the most important issues in battery design and applications. The heat generated by electrochemical reactions must dissipate outside the battery to prevent thermal runway.The heat generation rate is an important thermal characteristic for battery design. Heat-generating sources are described in three fields of study: electricity, electrochemistry and thermodynamics. The electrical explanation shows that heat generation is the difference between the power in open-circuit voltage and the payload power. 5 The electrochemical approach reveals three types of heat generation sources: ohmic Joule heat, active polarization heat and reaction entropy heat. 6-8 Thermodynamic models vary from a zero-dimensional lumped-capacitance model to a three-dimensional thermal model. [7][8][9][10][11][12][13][14] Heat generation may be measured according to three means of heat transfer: conduction, convection and radiation. 15 Pesaran et al. 16 introduced a heat conduction type calorimeter to obtain heat generation data from battery modules. The battery sample was surrounded by an isothermal bath. The thermal gradient between the sample and the bath was compensated by calibration heaters. Al-Hallaj et al. 17 applied the lumped-capacitance thermal model, including conductive and convective experimental methods, to measure heat generation. First, the battery was fastened inside the cavity of an insulator; therefore, heat conduction was the main means of heat transfer, and convection and radiation were negligible. 8,18 Then, the battery was not insulated inside the calorimeter, and nat...

The specific heat capacity of lithium thionyl chloride batteries is measured with precise specific heat capacity test apparatus. The experiment instrument is calibrated with standard sample brass with the same geometry of battery. Different heating end temperatures during the measurement do not affect the heat capacity measurements. Experiment analysis reveals that the heat loss part which is not proportional to the calorimeter liquid temperature change cannot be neglected. The heat capacity is independent on the discharge current. At 100% depth of discharge, the battery loses 17.1% of the initial heat capacity 904 J kg −1 K −1 . Both experimental and computational results show that the heat capacity reduces as battery discharges at certain currents, and this is different from available published results. Heat capacity loss increases the difficulty of battery module thermal design especially at the end of discharge when both the ambient temperature and the interior battery temperature are high.

A modified steady-state thermal conductivity measurement method that adds a thermal compensation device (TCD) is proposed. Calibration experiments verify that the heat loss rate of the test apparatus is less than 5.0%. The thermal conductivities of the spirally wound cylindrical Li/SOCl 2 batteries are measured at different discharge currents (1.0 A, 1.2 A, and 2.0 A) and at different depths of discharge (DOD) (0% DOD, 50% DOD, and 100% DOD). The measured values exhibit a dependence on the DOD and independence from the discharge current. To validate the test method, a model combining a statistical averaging method with a hybrid computing strategy is established to simplify the calculation model; the model considered influencing factors, such as physical uncertainty and the shape irregularity of the Li/SOCl 2 battery. The tendency for thermal conductivity to decrease when DOD increases demonstrates that the measurement and simulation are consistent. The analysis results indicate that the consumption coefficient (f) is an important factor for the thermal conductivity of a Li/SOCl 2 battery. At a constant DOD, the overall axial thermal conductivities decrease significantly when the consumption coefficient increases. Therefore, when designing batteries, the change in the thermal conductivities relative to the consumption coefficient and DOD should be monitored.

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