SnO2/Carbon Nanotube–Infiltrated Ni Nanofoams As 3D Anodes for Enhanced Performance of Lithium-Ion Batteries

Metallic nanofoams have been widely investigated as 3D current collectors in lithium-ion batteries (LIBs) due to their high stability and mechanical robustness, as well as the highly conductive 3D framework that can be coated with high-capacity anode materials. However, the extremely high porosities (> 99%) and low specific surface areas (< 10 m²/g) of metallic nanofoams, limits the amount of active electrode material that can be deposited, thus reducing the maximum achievable areal energy density. Although the weight penalty associated with metallic nanofoams is a disadvantage, their highly conductive interconnected fibers and high void fraction could be exploited for improved LIB performance by infiltrating the nanofoam with a highly conductive, low-density material such as carbon nanotubes (CNTs). Here, we report for the first time, an efficient and scalable gas-phase liquid injection CVD approach using a ferocene/xylene mixture for the infiltration of arrays of high-quality CNTs in pretreated Ni nanofoam. Importantly, the BET specific surface area of the pretreated Ni nanofoam after CNT infiltration increases by a factor of over 20. Further, upon deposition of SnO₂ on the CNT-infiltrated Ni nanofoams by atomic layer deposition, the new nanocomposites showed improved energy capacity and excellent rate capability, as well as high capacity retention during electrochemical charge-discharge measurements.