Silicon nanowires (Si NWs) have been identified as an excellent candidate material for the replacement of graphite in anodes, allowing for a significant boost in the capacity of lithium‐ion batteries (LIBs). Herein, high‐density Si NWs are grown on a novel 3D interconnected network of binary‐phase Cu‐silicide nanofoam (3D CuxSiy NF) substrate. The nanofoam facilitates the uniform distribution of well‐segregated and small‐sized catalyst seeds, leading to high‐density/single‐phase Si NW growth with an areal‐loading in excess of 1.0 mg cm−2 and a stable areal capacity of ≈2.0 mAh cm−2 after 550 cycles. The use of the 3D CuxSiy NF as a substrate is further extended for Al, Bi, Cu, In, Mn, Ni, Sb, Sn, and Zn mediated Si NW growth, demonstrating the general applicability of the anode architecture.
Here we report the formation of three distinct Sn-based active materials for Li-ion battery anodes, formed from the same metal−organic material (MOM) precursor sql-1-Cu-SNIFSIX. The materials were obtained under three different anneal conditions in air, Ar, and a Se-rich atmosphere, leading to the selective formation of SnO 2 /CuO/C (oxide), Cu 6 Sn 5 /C (stannide), and Cu 2 SnSe 3 /SnSe 2 /C (selenide) composites. The lithiation and delithiation mechanisms were investigated for each material in the potential range of 0−3 V. Over extended cycling periods, the reversible alloying of Li with Sn was the only process evident for the stannide, with minimal activity occurring at potentials greater than 1 V. In contrast to this, the oxide and selenide composites exhibit both conversion (1−3 V) and Li/Sn alloying (0−1 V) behavior in this potential range; however, the stability of the conversion reaction was found to be poor, inhibiting the capacity retention of both materials. Notably, when the reaction mechanisms were restricted to Li/Sn alloying only by limiting the potential range to 0−1 V, all three composite materials significantly outperformed a Sn nanopowder electrode, illustrating the benefits of utilizing composite electrodes to stabilize the Sn alloying reaction over extended cycling periods.
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