Facile Synthesis of Nickel Nanofoam Architectures for Applications in Li-Ion Batteries.

Metal foams are utilized in various applications, such as in the automotive industries and for electrochemical devices. Herein, a Ni nanofoam is synthesized using a facile method for Li-ion batteries. Self-aligned Ni wires or randomly linked webs are produced with or without magnetic field, respectively. Ni granular beads or spiky clusters form at 370 or 450 °C, respectively. The surface area of Ni wires is increased by oxalic acid etching at 80 °C using 5-30 wt % water, leading to Ni oxalate nanosheets, nanowires (NWs), or nanoleaves. Metallic Ni NWs are obtained by reducing Ni oxalate NWs with H₂ at 350 °C in 10 min. Carbon-coated Si nanoparticles on Ni NW foam (C-Si NP/Ni NWF) show 38 % rate enhancement (1222 vs. 889 mAh g⁻¹) in comparison to C-Si NP/Cu foil. Higher stability of C-Si NP/Ni NWF with a capacity retention of 91 % is reached vs. 73 % for C-Si NP/Cu foil over 180 cycles. The ambient-pressure solution process with low temperature and fast reaction time could make large-scale production plausible for these nanoarchitectures. [ABSTRACT FROM AUTHOR]