Preprint of "Atmosphere-Dependent Surface and Phase Evolution of Spent NMC622 and Graphite Electrodes during Low-Temperature Thermal Pre-Treatment"

This paper investigates the atmosphere-dependent surface and phase evolution of integrated NMC622 and graphite electrodes during thermal pre-treatment at 500 °C. It demonstrates that while oxidative roasting destroys the carbon fraction, inert (Ar) and reductive (H2) atmospheres successfully preserve the valuable graphite anode. Furthermore, the study identifies a novel hydrogen-induced "morphological metamorphosis" that opens up the cathode structure through metallic whisker growth, while mapping the challenges of "alumina blanketing" from separator residues. The work provides a sophisticated surface engineering strategy to chemically pre-activate black mass and maximize multi-material recovery for a circular economy.