Thermo-mechanical polymer binder reactivity with positive active materials for Li metal polymer and Li-ion batteries: an XPS and XPS imaging study.

The lithium and lithium-ion batteries electrodes chemical stability in the pristine state has rarely been considered as function of the binder choice and the electrodes processing. In this work, X-ray Photoelectron Spectroscopy (XPS) and XPS imaging analyses associated with complementary Mossbauer spectroscopy are used in order to study the chemical stability of two pristine positive electrodes: (i) an extruded LiFePO4 (LFP)-based electrode formulated with different polymer matrices (polyethylene oxide (PEO) and a polyvinylidene difluoride (PVdF)) and processed at different temperatures (90 °C and 130 °C respectively) and (ii) a Li[Ni0.5Mn0.3Co0.2]O2 (NMC)-based electrode processed by tape casting, followed by a mild or heavy calendering treatment. These analyses have allowed the identification of reactivity mechanisms at the interface of the active material and the polymer in the case of the PVdF-based electrodes.