Enhancing the electrochemical performance of Ni-rich cathode through an in-situ La-doping and La4NiLiO8-coating synergistic strategy
Ni-rich layered oxides offer numerous advantages such as high discharge capacity, cost-effectiveness, and environmental friendliness, making them the mainstream cathodes for high-energy density lithium-ion batteries. However, their widespread commercialization is hindered by critical challenges in cycling performance, stemming from unstable interface and structure, particularly at elevated charge cut-off voltages. Herein, a dual-modification strategy combining La doping and La 4 NiLiO 8 coating was proposed to synergistically enhance the surface/interface and structure stability of the LiNi 0.83 Co 0.11 Mn 0.06 O 2 (referred to as NCM83) cathode. Unlike conventional methods, a well-designed La(OH) 3 coating pretreatment was employed on the Ni 0.83 Co 0.11 Mn 0.06 (OH) 2 precursor. This pretreatment aimed to facilitate the in-situ formation of La doping and La 4 NiLiO 8 during the lithiation of the coated precursor, while ensuring desired uniformity of the La 4 NiLiO 8 coating and La doping. This dual-modification strategy integrated the advantages of both La doping and La 4 NiLiO 8 coating, demonstrating excellent capability to improve the overall performance of NCM83. The La doping, acting as a pillar, not only strengthened the layered structure of the cathode to mitigate volume changes, but also enhanced Li + diffusion by broadening the c axis spacing. The La 4 NiLiO 8 coating efficiently protected the cathode from H 2 O/CO 2 attack and electrolyte erosion, while also facilitating Li + transport owing to its favorable Li-conductive properties. Such a dual-modification strategy significantly enhanced the electrochemical performance of NCM83, as demonstrated by the excellent long-term cyclic stability, rate capability, and thermal stability at a high charge cut-off voltage of 4.5 V. This work highlighted the benefits of integrating elemental doping and surface coating, while offering a promising synthetic protocol for straightforward and effective dual-modification of various cathodes.
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