Boron Doping and LiBO₂ Coating Synergistically Enhance the High-Rate Performance of LiNi₀.₆Co₀.₁Mn₀.₃O₂ Cathode Materials

The nickel-rich cathode LiNi₀.₆Co₀.₁Mn₀.₃O₂ (NCM613) is a promising cathode material but has poor cycle stability, especially at a high cutoff voltage. Aiming at modulating the unit cell parameters via heteroatom dopants while providing a lithium-ion conductor coating, in this work, boron-based-modified NCM613 has been synthesized with both LiBO₂ coating and boron doping via a solid-state method. The optimal modified sample LBO-0.4 exhibits excellent cycle stability at room temperature (2.8–4.5 V) with a retention of 94.8% at 1 C after 100 cycles (versus 79.7% of the pristine sample LBO-0) and 70.7% at 5 C after 1000 cycles (versus a retention lower than 1% for LBO-0). The DLᵢ⁺ values of LBO-0.4 are significantly higher than those of LBO-0, which is attributed to the enlarged crystal lattice volume generated by the incorporation of B³⁺ into NCM613. Combined with characterization by Ar sputtering-assisted XPS, TEM, XRD, etc., it is illustrated that LiBO₂ coating and B³⁺ doping can synergistically enhance the electrochemical performance of the NCM613 at a high cutoff voltage, high temperature, and high rate. In addition, DFT calculations disclose that the boron dopant is preferential to locate in the interstice among three Ni atoms of the TM–O layer of NCM, which facilitates the formation of more amount Ni²⁺, leading to the improved electrochemical performance of NCM613. Such ion doping and surface coating strategy can provide useful guidance on the modification of other layered oxide cathode materials.