ScholarWorks@숙명여자대학교

초록

The conformal surface coating of Ni-rich layered cathode materials is essential for mitigating their interfacial and subsequent structural degradation. The zirconia (ZrO2) coating effectively enhances the surface stability of the cathode owing to its excellent chemical durability; however, the insulating electrical conductivity of ZrO2 increases the electrode resistance and triggers efficiency decay. Here, we propose highly conductive oxygen-deficient black ZrO2-x as a charge-conductive coating material. The black ZrO2-x is uniformly coated onto the Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC) surface via a solvent-free mechanochemical shearing process. Benefiting from the black ZrO2-x coating layer, black ZrO2-x coated NMC shows improved cycling characteristics and better rate capability than both bare NMC and ZrO2 coated NMC. The enhanced electrochemical performance by the conformal coating of black ZrO2-x mainly results from enhanced charge transfer, reduced gas evolution, and mitigated microstructural cracking. Density functional theory calculations confirm that the defective structure of black ZrO2-x lowers the energy barrier for Li ion transfer, and strong hybridization between Zr in black ZrO2-x and O in NMC mitigates oxygen evolution. Black ZrO2-x is coated onto a Ni-rich cathode via solvent-free shearing, enhancing charge transfer, reducing gas evolution, and preventing cracking. It lowers Li-ion transfer barriers and mitigates oxygen release through strong Zr-O hybridization.

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