Ni-rich cathode materials show promise for use in lithium-ion batteries. However, a significant obstacle to their widespread adoption is the structural damage caused by microcracks. This research paper presents the synthesis of Ni-rich cathode materials, including LiNi0.8Co0.1Mn0.1O2 (referred to as NCM) and Li(Ni0.8Co0.1Mn0.1)0.98Al0.02O2 (referred to as NCMA), achieved through the high-temperature solid-phase method. Electrochemical (EC) testing results reveal the impressive EC performance of NCMA. NCMA exhibited a discharge capacity of 141.6 mAh g–1 and maintained a cycle retention rate of up to 74.92% after 300 cycles at a 1 C rate. In contrast, the NCM had a discharge capacity of 109.7 mAh g–1 and a cycle retention rate of 61.22%. Atomic force microscopy showed that the Derjaguin−Muller−Toporov (DMT) modulus value of NCMA exceeded that of NCM, signifying a greater mechanical strength of NCMA. Density functional theory calculations demonstrated that the addition of aluminum during the delithiation process led to the mitigation of anisotropic lattice changes and the stabilization of the NCMA structure. This improvement was attributed to the relatively stronger Al–O bonds compared to the Ni(Co, Mn)–O bonds, which reduced the formation of microcracks by enhancing NCMA’s mechanical strength.
Ting Li,Jinhua Xu,Guojing Cao,Xiaoxue Jiang,Cuiqin Li
The ultrahigh-nickel quaternary cathode material LiNi 1-x-y-z Co x Mn y Al z O 2 (1-x-y-z ≥ 0.9, NCMA) combines the complementary advantages of its ternary counterparts, LiNi x Co y Mn z O 2 (x≥0.9, NCM) and LiNi x Co y Al z O 2 (x≥0.9, NCA). Benefiting from its high specific capacity and exceptional rate capability, the NCMA cathode has attracted widespread attention as a promising candidate for the high-end energy storage market. However, oversized primary particles typically exacerbate internal stress, leading to secondary particle pulverization and microcrack propagation, which severely degrade cycling stability and trigger capacity fade. To address these limitations, this study introduces Mo 6+ doping into NCMA to guide the radial growth of primary particles, resulting in a distinct elongated, rod-shaped morphology. This structural modification effectively shortens Li + transport pathways and mitigates internal-stress-induced microcracks. Concurrently, the dual roles of Mo are elucidated: its incorporation into the bulk lattice induces lattice expansion that widens Li + diffusion channels, while its segregation at grain boundaries restricts grain growth and fosters the radial morphology. This synergistic effect significantly accelerates Li + transport kinetics during cycling. Consequently, the optimized Mo-doped NCMA delivers a high reversible capacity of 213.5 mAh·g -1 at 0.2 C, 134.9 mAh·g -1 at 10 C, and a 94.9% retention rate after 100 cycles at 1 C. Furthermore, its practical viability was further assessed in a full-cell configuration, which maintained stability over 500 cycles and delivered 72.13% capacity retention. Overall, the Mo 6+ doping strategy successfully enhances the electrochemical performance of NCMA, offering a promising avenue for the modification of ultrahigh-nickel quaternary cathode materials.
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