In this study, nanoscale copper(I) sulfide (n-Cu2S) was deposited over networks of single-walled carbon nanotubes (SWCNTs) by atomic layer deposition (ALD). This synthetic route provides a high degree of control for tuning the materials properties. The resulting core–shell SWCNT-n-Cu2S composite structure ensures an intimate contact between the two components while maintaining a high porosity for efficient transport of charges. Indeed, electrochemical testing demonstrates that these nanocomposites are promising as cathodes in lithium-ion batteries (LIBs), exhibiting excellent stability over 200 discharge–charge cycles with a sustainable, high capacity of 260 mAh g−1 (92% of the theoretical value in terms of Cu2S) and >99% Coulombic efficiency. This work establishes a general strategy for developing high-performance nanoscale electrode materials.