All-Dry Synthesis of NMC from [Ni,Mn,Co] 3 O 4 Spinel Precursors

Oxides in the Ni x Mn 0.5- x /2 Co 0.5- x /2 -O system were investigated as precursors in the all-dry synthesis of NMC622 (LiNi 0.6 Mn 0.2 Co 0.2 O 2 ). Single-phase spinel precursors in this system were found to have the highest compositional homogeneity. To synthesize NMC, Ni x Mn 0.5- x /2 Co 0.5- x /2 -O precursors were heated with Li 2 CO 3 and NiO (to attain the correct NMC stoichiometry) in air or oxygen. This represents a different strategy in NMC synthesis compared to conventional hydroxide precursors that have the same composition as the final NMC. The most homogeneous and best performing NMC (171.9 mAh g −1 with 90% after 183 cycles) were obtained by using precursors that were essentially single-phase cubic spinel (0.070 ≤ x ≤ 0.091 in Ni x Mn 0.5- x /2 Co 0.5- x /2 -O) even though such precursors had compositions that had significantly less Ni content than the target NMC622 composition. These findings demonstrate an alternate route for obtaining compositional homogeneity in NMC all-dry synthesis.