Reduction pathways of LiNi0.6Co0.2Mn0.2O2 to metallic Ni-Co-Mn: a comparison of H2, CH4, and NH3

We investigate H 2 , NH 3 , and CH 4 for direct waste-to-resource conversion of spent Li-ion battery, using LiNi 0.6 Co 0.2 Mn 0.2 O 2 as a representative cathode oxide to produce Ni-Co-Mn master alloys for steelmaking. In-situ X-ray diffraction tracks phase evolution during heating to 950 °C in all three gases, showing reduction via Ni 0.6 Co 0.2 Mn 0.2 O intermediate to Ni-Co-Mn metallic alloy. Metallography after diffraction confirms complete reduction of Ni and Co in all atmospheres, while some MnO remains after 30-min hold at 950 °C in H 2 and NH 3 . H 2 provides the cleanest pathway, generating mainly H 2 O and avoiding carbide or nitride formation, but complete MnO reduction would require higher temperature or longer holds. NH 3 approaches the H 2 reduction level without detectable nitrides, but shows higher MnO retention and corrosive handling requirements. CH 4 fully reduces MnO with stronger CO-driven reduction at high temperature. However, CO and CO 2 generation undermines sustainability and carbon deposition may limit its practical value for steelmaking.