Preparation of modified high-nickel layered cathode with LiAlO2/cyclopolyacrylonitrile dual-functional coating
The structural and interfacial instability of high-nickel layered cathode material(NCM811)were improved by the construction of inorganic-organic dual-coating.The dual-coating layer was composed of nano lithi-um metaluminate(LiAlO2,LAO)and cyclopolyacrylonitrile(cPAN).The LAO is a typical lithium-ion conductor,which can be used as a surface coating material to ensure rapid Li+migration at the interface.In addition,the polyac-rylonitrile(PAN)undergoes cross-linked cyclization reactions,resulting in the formation of a delocalized π bond and the formation of the cPAN with electronic conductivity after low-temperature heat treatment.The structure and composition of the dual-coating layer were carefully characterized,which indicates its uniform distribution on the surface of the NCM811 material.The as-obtained modified sample showed an electrochemical capacity retention of 84.8％after 150 cycles in the voltage range of 2.7-4.3 V(vs Li/Li+)at the current density of 1C(180 mA·g-1).Under the same test conditions,the capacity retention of pristine NCM811 was only 65.5％.The dual-coating layer can effectively protect the active material and could reduce the electrolyte decomposition on the material surface to a certain extent,leading to a decrease in interfacial impedance.
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