18650 Cells accelerating rate calorimeter

The experimental techniques described above of charge—discharge and impedance are nondestructive. Tear-down analysis or disassembly of spent cells and an examination of the various components using experimental techniques such as Raman microscopy, atomic force microscopy, NMR spectroscopy, transmission electron microscopy, XAS, and the like can be carried out on materials-spent battery electrodes to better understand the phenomena that lead to degradation during use. These techniques provide diagnostic techniques that identify materials properties and materials interactions that limit lifetime, performance, and thermal stabiity. The accelerated rate calorimeter finds use in identifying safety-related situations that lead to thermal runaway and destruction of the battery. 

Figure 4.3 Principles of the accelerating rate calorimeter showing the oven with the sample holding cells in its center. T thermocouple, H heater, Th thermostat, P pressure transducer.

Richard MN, Dahn JR (1999) Predicting electrical and thermal abuse behaviours of practical lithium-ion cells from accelerating rate calorimeter studies on small samples in electrolyte. J Power Sources 79 135-142... 

For experiments conducted at slower heating rates under adiabatic conditions, the accelerating-rate calorimeter (ARC) is the instrument of choice [13]. The ARC allows precise control of temperature and exposes the cell to more uniform conditions over longer periods. A typical experiment requires a few days rather than a few hours, as in the case of the heating block. Because of the adiabatic environment, the onset of self-heating due to chemical reactions in the interior of the cell can be detected with greater sensitivity. 

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