Heat Generation of a Lithium Coin Cell Measured with a DSC-Like Battery Calorimeter

摘要

Important for designing new materials for batteries and the Thermal Management System is to know the amount of heat during charging and discharging. With our battery calorimeter (Netzsch MMC 274 Nexus), we can measure precisely quantitatively the generated heat during charging and discharging at isothermal, heating or HEAT-wait-Search-mode at different C-rates and temperature. Small thermal effects can be determined to understand the chemistry in the battery or even to characterize the strength of the SEI layer. Knowing about the heat generation, the total energy efficiency (electrical energy and heat release), thermal stability or even the change of heat signature after life-cycle tests, helps to develop new battery materials and the Thermal Management System. Our DSC-like battery calorimeter is equipped with a high temperature coin cell module. It enables to measure precise the generated heat during charging and discharging at isothermal, heating or Heat-Wait-Search mode. The temperature range can be varied from room temperature up to 300℃ at a heating rate from 0,001 to 5 K/min. The sensor is calibrated by the melting temperature and enthalpy of 5 substances. Measurements between 20-300℃ with a resolution of 0.001 K and 10µW up to 370 mW enables to measure exothermic and endothermic effects during cycling or heating a coin cell. Chemical and physical changes can be identified in the electrode materials as for example phase transformation. Thus, it is possible to obtain valuable information for phase stabilities of the electrode, electrolyte and separator materials. Onset temperatures will be shown for decomposition reactions simultaneously with the quantity of released heat during an induced thermal runaway. The measured heat generation during cycling between 30-50℃ under different C-rates will be shown as well as the influence of thermal degradation on the measured heat. Thus, it is possible to obtain valuable information for phase stabilities of the electrode, electrolyte and separator materials. Onset temperatures will be shown for decomposition reactions simultaneously with the quantity of released heat during an induced thermal runaway. The measured heat generation during cycling between 30-50℃ under different C-rates will be shown as well as the influence of thermal degradation on the measured heat.