Interfacial reaction-modulating single-walled carbon nanotubes for enhancing the high-rate capability of Ni-rich LiNi0.92Co0.04Mn0.04O2 cathodes in lithium-ion batteries

초록

Ni-rich layered cathodes are promising for next-generation lithium-ion batteries owing to their high energy density, but their high-rate performance remains limited by coupled kinetic bottlenecks and interfacial instabilities in composite electrodes. Here, we investigate whether conductive-additive surface chemistry can be used to modulate cathode interfacial reactions and cathode-electrolyte interphase (CEI) evolution under highrate conditions using oxygen-functionalized single-walled carbon nanotubes (Ox-SWCNTs). Compared with pristine SWCNTs (P-SWCNTs), Ox-SWCNTs introduced oxygen-containing surface functionalities that increased electrochemically accessible Li-storage sites and altered early-stage interfacial chemistry. Consequently, the OxSWCNT electrode showed moderately improved high-rate performance, including higher capacity retention at 2C relative to 0.1C (74% vs. 68%), higher initial discharge capacity at 2C (194 vs. 182 mAh g- 1), and higher 100cycle retention at 2C (67% vs. 50%). Interfacial analyses revealed a thinner, more uniform, and more inorganicrich CEI containing LiF- and LixPOyFz-related species, along with more homogeneous Li+ distribution after formation and repeated high-rate cycling. These results show that conductive additives can be designed to actively regulate cathode interfacial reactions and CEI evolution, with Ox-SWCNTs serving as interfacial reaction modulators rather than passive electron-percolation agents.

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