Revealing the Mechanism of Mg–Cu Heterolayer Doping on Ni/Li Migration Dynamics for NCM811 Cathode

Heterolayer elemental doping strategies have been demonstrated to be effective in improving properties of Ni-rich cathode materials, such as inhibiting Li+/Ni2+ disorder and enhancing Li+ extraction, thereby contributing to maintaining structural stability and improving reaction kinetics. Therefore, revealing the mechanism of heterolayer doping on Ni-rich materials is the key to designing high-performance cathode materials. The LiNi0.8Co0.1Mn0.07Mg0.015Cu0.015O2 (NCM811-CM) based on a high-throughput thermodynamic screening is characterized by a doped Mg and Cu heterolayer. Electronic structure calculations of NCM811-CM show that heterolayer doping of Cu2+ and Mg2+ can raise the valence state of Ni around Mg and increase the Coulomb repulsion between Ni and Mg, which inhibits Ni migration. In addition, the reversible deformation of the [CuO6] polyhedron widens the pathway for Li migration, leading to an increased ion migration rate. Compared to NCM811, NCM811-CM has higher structural stability and ion migration dynamics than NCM811, achieving excellent capacity retention of 94.91% after 100 cycles and exhibiting good Li+ mobility (1.17 × 10–10 cm2 s–1). These findings provide valuable insights into the stabilization mechanisms and enhanced migration dynamics facilitated by heterolayer doping, guiding the development of next-generation Li-ion batteries with improved cycle stability.