Publications OK SMART LAB

Ultrafine edge-split copper oxide nanoneedles for high-energy, fast-charging lithium-ion capacitors
Authors
J. Lee, Y. Lee, S. H. Shin, J. G. Ok, K. Park, and J. Y. Seok
Journal
Sustainable Materials and Technologies.
Vol. (No.), pp.
Volume 45, e01498
Year
2025
Developing lithium-ion capacitors (LICs) that simultaneously deliver high energy and power densities without compromising cycle life remains a critical challenge for next-generation energy storage systems. Herein, we report ultrafine copper oxide (CuO) nanoneedle anodes directly grown on copper foil current collectors via a synergistic double nano-structuring strategy. First, Cu nanopillars (∼160 nm in diameter) are self-assembled on Cu foil through a galvanic displacement reaction. These pillars are subsequently transformed into edge-split Cu(OH)2 nanoneedles as thin as ∼30 nm by ammonia-assisted electro-oxidation in an aqueous electrolyte. A subsequent annealing step dehydrates the Cu(OH)2, yielding CuO nanoneedles endowed with abundant nanopores (1.5–8 nm) and a high specific surface area of 59.71 m2 g−1. This hierarchically porous, ultrafine architecture markedly enhances electrochemical kinetics. As a result, the CuO nanoneedle anodes exhibit excellent rate capability and cycling stability, delivering specific capacities of 973 mAh g−1 at 0.2 A g−1 and 663 mAh g−1 at 5 A g−1. When paired with activated carbon cathodes, the LIC devices demonstrate outstanding rate performance, achieving an energy density of 110.1 Wh kg−1 at 2C and retaining ∼40 % of their capacity at an ultrafast rate of 60C. This facile fabrication route for ultrafine CuO electrode is expected to offer a promising pathway toward advanced energy storage applications.