Exploring a Ni-Co-Mn oxide precursor route via flame-assisted spray pyrolysis for the preparation of ternary cathode materials

Abstract

The conventional co-precipitation wet chemical method for preparing LiNi_xCo_yMn_1-x-yO₂ (NCM) cathode materials for lithium-ion batteries starts with the synthesis of Ni-Co-Mn hydroxide precursors, which are then calcined at high temperatures and thermally decomposed into oxides, followed solid-state reacting with lithium sources to obtain the NCM cathode materials. However, this hydroxide precursor route has several drawbacks, including multiple processing steps, pollution from strong bases, significant generation of liquid waste, and high energy consumption. In the current study, the Ni-Co-Mn oxide precursor route is explored via flame-assisted spray pyrolysis (FASP), which offers prompt reaction time, very few steps, and equipment without producing liquid wastes. Specifically, two types of oxide precursors, NiCoMnO₄ and Ni_0.8Co_0.1Mn_0.1O_1.1, were synthesized by FASP utilizing the co-flow diffusion flame burner system, which were subsequently mixed with cost-effective lithium carbonate (Li₂CO₃) and subjected to calcination, resulting in the preparation of two types ternary NCM cathode materials, NCM111 and NCM811. Characterization results demonstrate that NiCoMnO₄ features a spherical mesoporous structure with a smooth surface, and a spinel-dominated composite oxide structure, whereas Ni_0.8Co_0.1Mn_0.1O_1.1 exhibits a rough particle surface with a predominant rock salt phase NiO structure. Electrochemical test results show that NCM111 and NCM811 cathode materials exhibited excellent cycling stability, showing capacity retention of 88.5 % and 87.1 %, respectively, after 100 cycles, outperforming that of commercial counterparts and conventional synthesis approaches documented in literature. Thus, the Ni-Co-Mn oxide precursor route via FASP establishes a viable approach for preparing ternary NCM cathode materials