Lithiation behavior of silicon nanowire anodes for lithium-ion batteries: Impact of functionalization and porosity

Metal-assisted chemical etching (MACE) provides a versatile way to synthesize silicon nanowires of different morphologies. We used MACE to synthesize oxide-free porous and nonporous SiNW for the use in anodes for lithium-ion batteries. To improve their processing behavior the SiNW were functionalized using acrylic acid. Differential capacity plots were used as a way to identify the degradation processes during cycling through tracking the occurrence of Li15Si4 and changes in polarization. The cycling performance between porous and nonporous SiNW differed regarding coulombic efficiency and cycling stability. The differences were attributed to the porous hull and its ability to reduce the volume expansion, although not through its porous nature but the reduced uptake of Li-ions.