Directly deposited antimony on a copper silicide nanowire array as a high-performance potassium-ion battery anode with a long cycle life

Antimony (Sb) is a promising anode material for potassium-ion batteries (PIBs) due to its high capacity and moderate working potential. Achieving stable electrochemical performance for Sb is hindered by the enormous volume variation that occurs during cycling, causing a significant loss of the active material and disconnection from conventional current collectors (CCs). Herein, the direct growth of a highly dense copper silicide (Cu15Si4) nanowire (NW) array from a Cu mesh substrate to form a 3D CC is reported that facilitates the direct deposition of Sb in a core-shell arrangement (Sb@Cu15Si4 NWs). The 3D Cu15Si4 NW array provides a strong anchoring effect for Sb, while the spaces between the NWs act as a buffer zone for Sb expansion/contraction during K–cycling. The binder-free Sb@Cu15Si4 anode displays a stable capacity of 250.2 mAh g−1 at 200 mA g−1 for over 1250 cycles with a capacity drop of ≈0.028% per cycle. Ex situ electron microscopy revealed that the stable performance is due to the complete restructuring of the Sb shell into a porous interconnected network of mechanically robust ligaments. Notably, the 3D Cu15Si4 NW CC is expected to be widely applicable for the development of alloying-type anodes for next-generation energy storage devices.