Multi-walled carbon nanotube-reinforced porous iron oxide as a superior anode material for lithium ion battery

Multi-walled carbon nanotube-reinforced porous iron oxide (Fe3O4/MWCNT) is synthesized by a two-step approach with porous Cu substrate serving as current collector. Porous Cu substrate is prepared through electroless deposition with hydrogen bubble serving as template. Fe3O4/MWCNT composites are prepared by the electrodeposition of Fe3O4 in the presence of dispersed MWCNTs from a Fe2(SO4)3 solution with MWCNT suspension. Results showed that Fe3O4 forms granular nanoparticles on the porous Cu substrate with several MWCNTs embedded in it. Adding MWCNTs changes the morphology of Fe3O4. Smooth Fe3O4, smooth Fe3O4/MWCNT, and porous Fe3O4 composites are also prepared for comparison. When used as anode materials, porous Fe3O4/MWCNT composites have a reversible capacity of approximately 601 mA h g−1 at the 60th cycle at a cycling rate of 100 mA g−1. This value is higher than that of the other materials. The reversible capacity at a cycling rate of 10,000 mA g−1 is approximately 50% of that at 100 mA g−1. Therefore, the MWCNT-reinforced porous Fe3O4 composite exhibits much better reversible capacity, capacity retention, and high-rate performance than the other samples. This finding can be ascribed to the porous structure of Fe3O4, better conductivity of porous Cu substrate and MWCNTs, and the morphology change of Fe3O4 nanoparticles upon the addition of MWCNTs.