Measurements of Entropy Changes of Battery Electrode Materials Using Electrochemical Isothermal Calorimetry

This study introduces an innovative approach for directly measuring the entropy changes upon lithiation (∆S Li ) of active battery materials at a specific temperature, employing electrochemical isothermal microcalorimetry (EIMC) through a protocol that consists of successive small loops. In contrast to ∆S Li found in existing literature, which are generally obtained indirectly using a potentiometric method by assessing the equilibrated open-circuit voltage (OCV) gradient over a temperature range, the values obtained for graphite and NMC811 have a low-level hysteresis. Furthermore, this method demonstrated a unique ability to quantify the significant intrinsic hysteresis present in silicon.