Transforming Single‐Crystal CuO/Cu₂O Nanorods into Nano‐Polycrystalline Cu/Cu₂O through Lithiation

Abstract

One‐dimensional single‐crystal CuO/Cu2O nanorods were fabricated by controlled oxidation of a copper substrate and examined as the active material in porous anodes for lithium‐ion batteries. Electrochemical testing against Li‐metal revealed that using sodium carboxyl methyl cellulose (CMC) as the binder enabled an excellent capacity retention for 50 cycles, while the use of polyvinylidene fluoride (PVDF) resulted in a continuous capacity fade. Transmission electron microscopy illustrated the phase composition and morphological changes throughout cycling, revealing that for both types of binders, lithiation of CuO and Cu2O disrupted the single‐crystal nanorod structure, producing multiple Cu/Cu2O nanograins within the rods. With continuous cycling the average grain size of these nanocrystals decreased. A significant difference between the CMC and PVDF binder electrodes was the irreversible formation of LiCuO during delithiation for the PVDF case, which can explain the continuous capacity fade. Scanning electron microscopy also revealed microcracks throughout the electrode surface when the PVDF binder was employed.

Review of Materials for Electrodes and Electrolytes of Lithium Batteries

“…After 100 charge-discharge cycles, the CuO electrode containing carbomethylcellulose (CMC) maintains a stable capacity of at least 200 mA•h/g, and in the electrode with PVDF, the capacity drops to 60 mA•h/g. Presumably, CMC has better adhesion to the surface of Cu2O/CuO nanowhiskers, adapting to the volume expansion of the anode during cycling [67].…”

Lithium Polymer Battery with PVDF-based Electrolyte Doped with Copper Oxide Nanoparticles: Manufacturing Technology and Properties

“…The addition of nanoparticles is widely used to improve the properties of lithium-ion batteries [11,12]. Copper oxide nanoparticles (CuO and Cu2O) are a promising material for batteries [13,14] due to their high theoretical capacity, low cost, ease of preparation, safety, and large surface area.…”