ScholarWorks@중앙대학교

초록

Ni-rich cathodes have emerged as leading power sources for next-generation electronics; however, they exhibit low cycling performance and limited stability during high-voltage operation. This study investigates the effect of a Ti–P composite surface coating on the high cut-off voltage cycling behavior of a layered Li(Ni0.6Co0.2Mn0.2)O2 (NCM622) cathode material. Using a conventional sol-gel method, an organic-containing Ti–P composite is synthesized and uniformly deposited onto the NCM622 surface to produce the PT-NCM622 cathode material. The resulting homogeneous amorphous coating on the cathode surface increases the proportion of Ni3 + . When incorporated into Li-ion batteries (LIBs), the PT-NCM622 cathode demonstrates superior electrochemical performance to pristine NCM622. Notably, the PT-NCM622 cathode maintains remarkable capacity retention at both cut-off voltages after 100 cycles at a 1 C rate (99.05 % and 96.53 % over voltage ranges of 3.0–4.3 and 3.0–4.5 V, respectively), with only a negligible increase in overpotential and markedly suppressed crack formation. Electrochemical transient analysis reveals that the overall resistance remains invariant. Additionally, high Li-ion diffusivity was observed after surface coating. These characteristics, highly beneficial to cathode performance, are attributed to strong coating compatibility with the cathode surface and the effective protective role of the coating against crystal collapse and electrolyte penetration. The proposed coating strategy enables Ni-rich NCM operation at high voltages and significantly enhances cycling stability. Particularly, the amorphous Ti–P coating provides distinct advantages over conventional coatings such as Al₂O₃, TiO₂, or Li₃PO₄ by simultaneously enhancing interfacial stability and Li⁺ transport, thereby supporting the development of next-generation high-energy-density LIBs.

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