Template-Free Electrochemical Synthesis of Cuprous Oxide and Its Application to Anode of Lithium Ion Batteries

Cu₂O has been investigated as a candidate of the promising anode materials for Lithium ion batteries (LIB) due to its several advantages such as reversible mechanism with Li ion, relatively low-cost, non-toxicity, and higher theoretical capacity than graphite. However, the Li ion charge and discharge (C-D) processes accompany huge volume expansion and shrinkage, by which mechanical stresses are induced and lead to poor C-D cycle life due to the failure of the contacts between anode material and current collector. In order to avoid the drawbacks of large volume change in anode material, several efforts have been taken to use Cu₂O nanopowders as an anode. However, the usage of nanopowders requires additional conductive carbon sources or binders which are disadvantageous in simplifying fabrication process and lowering cost.

In this talk, we present a template-free and surfactant-free electrochemical nanosynthesis of single crystalline Cu₂O nanostructures. The electrochemical growth of Cu₂O nanostructures originated from filamentary effect related to the electric field enhancement on the pyramidal Cu₂O grains in an ultra-dilute CuSO₄ aqueous electrolyte. The synthesized Cu₂O nanorods showed much more excellent electrochemical properties as an anode material for LIBs than Cu₂O films; the electrochemical capacities exceptionally increased from 340 to 1249 mAh/g during 500 cycles exceeding the theoretical capacity of Cu₂O. The capacity enhancement was due to the phase transformation from Cu₂O to CuO, nanostructuring from nanorods to fragmented nanoparticles, and progressive generation of electroactive polymeric gel-like layer on the surface of the nanoparticles. The present nanostructuring of Cu₂O is expected to contribute to the development of higher capacity LIBs in near future.