Facile In-Situ Synthesis of Freestanding 3D Nanoporous Cu@Cu₂O Hierarchical Nanoplate Arrays as Binder-Free Integrated Anodes for High-Capacity, Long-Life Li-Ion Batteries

Freestanding 3D nanoporous Cu-supported Cu₂O hierarchical nanoplate arrays (3D NPC@Cu₂O HNPAs) have been prepared in situ by facile one-step oxidation-assisted electrochemical dealloying, in which Cu₂O HNPAs are characteristic of large-sized (hundreds of nm) 2D nanoplate arrays firmly embedded in small-sized (tens of nm) counterparts. The unique 3D nanocomposites as anodes for Li-ion batteries (LIBs) display superior Li storage properties involving ultrahigh specific capacity, long cycle life and excellent rate capability, which deliver a reversible capacity as high as 3.0 mAh cm⁻² with 71.4 pct capacity retention after 450 long cycles at 2 mA cm⁻². Even when the current density reaches 5 mA cm⁻², an ultrahigh reversible capacity of 3.4 mAh cm⁻² still can be achieved smoothly without obvious capacity decay after 250 cycles. It is totally comparable to or even exceeds the current level of a commercial graphite anode. The outstanding electrochemical performance can be largely ascribed to the unique 3D electrode structure comprising HNPAs and NP substrate, the large contact area between active material and electrolyte, in situ growth of active material upon the porous substrate, a compact joint of small-sized intermediate nanolayers and favorable mass transfer among vertical hierarchical nanoplates, indicative of a quite promising candidate as a binder-free integrated anode toward practical application of advanced LIBs.