Highly Connected Silicon-Copper Alloy Mixture Nanotubes as High-Rate and Durable Anode Materials for Lithium-Ion Batteries

Seeking high-capacity, high-rate, and durable anode materials for lithium-ion batteries (LIBs) has been a crucial aspect to promote the use of electric vehicles and other portable electronics. Here, a novel alloy-forming approach to convert amorphous Si (a-Si)-coated copper oxide (CuO) core-shell nanowires (NWs) into hollow and highly interconnected Si-Cu alloy (mixture) nanotubes is reported. Upon a simple H-2 annealing, the CuO cores are reduced and diffused out to alloy with the a-Si shell, producing highly interconnected hollow Si-Cu alloy nanotubes, which can serve as high-capacity and self-conductive anode structures with robust mechanical support. A high specific capacity of 1010 mAh g(-1) (or 780 mAh g(-1)) has been achieved after 1000 cycles at 3.4 A g(-1) (or 20 A g(-1)), with a capacity retention rate of approximate to 84% (approximate to 88%), without the use of any binder or conductive agent. Remarkably, they can survive an extremely fast charging rate at 70 A g(-1) for 35 runs (corresponding to one full cycle in 30 s) and recover 88% capacity. This novel alloy-nanotube structure could represent an ideal candidate to fulfill the true potential of Si-loaded LIB applications.