The effect of B₂O₃/Li₃BO₃ coating and B³⁺ doping on electrochemical properties in nickel-rich single-crystal LiNi_0.7Co_0.2Mn_0.1O₂ cathodes

The sluggish ionic transport and interface stability for single-crystal nickel-rich materials are the main challenge hindering its large-scale applications. Herein, the single-crystal LiNi_0.7Co_0.2Mn_0.1O₂ (NCM) cathode is treated with H₃BO₃ through a simple wet chemical process. Surprisingly, H₃BO₃ shows multifunctional effect on the electrochemical performance of NCM, both through a generation of B₂O₃/Li₃BO₃ coating layers and B³⁺ incorporation into the bulk phase, and the fundamental understanding of multifunctional effect are investigated through crystal structure and chemical states. The B₂O₃/Li₃BO₃ coating layers act as artificial barriers and Li⁺-conductor on the surface, which inhibit Ni dissolution and accelerate lithium ions migration. Additionally, B³⁺ doping can strengthen Li⁺ diffusion rate in the layered structure. As a result, the electrochemical performance of the modified NCM material is enhanced. The 87.4% capacity retention of the initial capacity after 150 cycles at 1 C with a high work voltage of 4.5 V and high reversible capacity of 162.7 mAh g⁻¹ at 10 C rate can be obtained through H₃BO₃ modification. The multifunctional effect of H₃BO₃ provides a reference for the development and modification of lithium ions cathode materials in the future.