Scalable interfacial engineering of uniaxially aligned CNT current collectors with lithiophilic carbon skin toward high-energy lithium batteries

Uniaxially aligned carbon nanotubes (UACNTs) combine ultralow density, superior electrical conductivity, and outstanding mechanical robustness, making them promising candidates for current collectors in next-generation energy storage systems. However, their intrinsically high specific surface area facilitates excessive formation of the solid–electrolyte interphase (SEI), leading to continuous consumption of active lithium (Li) and hindering their practical application as current collectors, particularly in anode systems. In this study, we propose a strategy that tailors the surface of UACNTs with an ultrathin, lithiophilic carbon skin (ULS) to suppress uncontrolled SEI formation and promote favorable electrochemical reactions. The introduction of the ULS layer onto the UACNT reduces the effective contact area between CNTs and the electrolyte, which significantly minimizes electrolyte consumption and enhances the initial Coulombic efficiency. Nitrogen-containing functional groups originating from polydopamine further improve surface lithiophilicity and electrical conductivity, and they enable uniform Li plating/stripping while suppressing the formation of inactive Li. These synergistic effects of the ULS layer result in a reduced initial irreversible capacity and superior cycling stability with high capacity in Li-ion battery evaluations. In Li-metal battery tests, the ULS–UACNT cells show excellent electrochemical stability. This work offers a practical route to mitigate interfacial challenges and enhance CNT-based current collector viability for next-generation batteries.