Exploring Structural Evolution and Lattice Oxygen Bonding Variation in Li-Rich NCM Cathode Materials

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Abstract
Ternary lithium-ion cathode materials, notably Nickel-Cobalt-Manganese (NCM), hold immense promise as key components for high-capacity and high-energy-density lithium-ion batteries. However, their long-term cyclability is hindered by several challenges, primarily attributed to interlayer migration of transition metals (TM), alterations in lattice oxygen bonding, and structural instability during extensive charge-discharge cycles. To address these limitations and gain a deeper understanding of the underlying mechanisms, we developed a deep potential model. This model, trained on comprehensive data from first-principles calculations and molecular dynamics simulations, enables highly accurate predictions of energies and forces across various structures. Leveraging this advanced tool, we conducted a rigorous investigation into the structural evolution and stability of lithium-rich NCM cathode materials. Our findings underscore the exceptional ability of Li1.188Ni0.250Co0.125Mn0.437O2 to significantly mitigate interlayer migration of TM ions, outperforming other compositions in this regard. Furthermore, we have elucidated the mechanisms governing TM ion migration and oxygen vacancy formation, highlighting how their interplay with lattice oxygen bonding leads to voltage hysteresis. These insights provide crucial guidance for designing and optimizing high-performance, structurally stable NCM cathode materials, with significant implications for next-generation electric vehicles and energy storage systems.
Funding Information
  • National Natural Science Foundation of China (11874307)

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