(190g) ALD Coatings on Mn Rich Layered-Layered NMC Cathodes to Inhibit Transformation to Spinel Phase to Mitigate Voltage Fade in Lithium-Ion Cells

High energy and long cycle life are the key technical attributes required for widespread implementation of high-performance electric vehicles (EVs). Despite significant strides made to-date, the current high energy density solutions suffer from degradation that prevents the implementation of lithium- and manganese-rich NMC cathode materials for a commercially viable EV industry. Capacity, power, and voltage fade, as well as excessive SEI growth, electrolyte oxidation, Mn (cathode) dissolution, structural degradation, and phase transformations are only a few of the mechanisms that have been identified. Layered-Layered structure to spinel phase transformations at high voltages (>4.6 V), are a main contributor to voltage fade in Layered-Layered Mn Rich cathode based Li-ion batteries. In this paper we show that atomic layer deposition (ALD) coatings applied to NMC powder, conformally applied to active material particle surfaces, create a controlled SEI layer which alters and slows the chemical pathways for nucleation and propagation of layered-to-spinel phase transformations at high voltages. XRD, TEM, and magnetic susceptibility characterization of active cathode materials showed significantly reduced phase transformation in coated NMC compared to uncoated materials. XALT Energy has integrated these coated materials in pouch cells of 95x64 mm size (2.5 Ah) and has demonstrated improvements; these cells’ performances are representative of large format (216x216 mm) production EV cells, demonstrating the validity and scalability of this approach.