A thin Si nanowire network anode for high volumetric capacity and long-life lithium-ion batteries

Silicon nanowires (Si NWs) have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries (LIBs) owing to their high capacity and low discharge potential. However, growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors (CCs), and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+ inactive silicide phases. Here, the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide (CS) network in situ grown on a Cu-foil, allowing for a thin active NW layer (<10 µm thick) and high areal loading ( ≈ 1.04 mg/cm2) binder-free electrode architecture. The electrode exhibits an average Coulombic efficiency (CE) of > 99.6% and stable performance for > 900 cycles with ≈ 88.7% capacity retention. More significantly, it delivers a volumetric capacity of ≈ 1086.1 mA h/cm3 at 5C. The full-cell versus lithium manganese oxide (LMO) cathode delivers a capacity of ≈ 1177.1 mA h/g at 1C with a stable rate capability. This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.