Lithium-Ion Batteries are commonly used in portable electronics, in electro mobility and in stationary storage systems. Nevertheless the demand for new electrode and electrolyte materials for Lithium-Ion Batteries is high to increase capacity, life-time and safety. The knowledge of basic thermodynamic data and phase equilibrium information form the basis for such developments. Such information is important to understand the electrochemical processes during cycling and for designing the battery thermal management system.
The experimental determination of the heat capacity is an important issue. The cp-value of a battery system consists of the individual constituents. It is important to know each cp-value of the inserted materials at different temperatures. With this information it is possible to design the battery thermal management system. Consequently thermal runaways may be prevented and the life time of a Lithium-Ion Battery can be increased. In this work the cp-value of the cathode materials LCO and NMC was measured between 300 K and 900 K. Additionally the heat capacity was modelled by using the Debye-Einstein model for the cathode material LCO. The results were compared with existing literature data.
Another key information for designing the thermal management system is to know the amount of heat during charging and discharging a battery. The generated heat during cycling can be measured by a battery calorimeter. The generated heat during discharging and charging of a coin cell was measured by a Netzsch Calorimeter MMC 274 Nexus. A commercial LiR2032 coin cell was therefore cycled by Constant Current-Constant Voltage mode at several temperatures. The DSC-like battery calorimeter is equipped with a high temperature coin cell module. Additionally information about electrochemical processes during charging and discharging will be shown such as exothermic or endothermic reactions. The heat and the temperature of a thermal runaway can be quantitatively and qualitatively described and will be presented.