Layer-by-layer anodes with an orientation-arranged structure induced by magnetic field for high-performance lithium ion batteries

Abstract

Fe₃O₄/carbon fibers (CFs) in a novel layer-by-layer (LBL) alignment as anodes for lithium ion batteries (LIBs) were successfully prepared through the assistance of a magnetic field. In this approach, Fe₃O₄ nanoparticles were deposited on carbon fibers by the sol–gel approach. Induced by a magnetic field, the alignment of Fe₃O₄/CFs was formed, and the LBL structure was fabricated by alternately dropping the hydrous and organic slurries of active materials. Due to the change in the orientation of the magnetic field, each subsequent prepared Fe₃O₄/CF alignment layer was vertical to the last one, and the electrical conductivity of Fe₃O₄/CFs, spaces for Li⁺ storage and channels for the diffusion of Li⁺ all sharply increased. Thus, a high electrochemical performance was achieved: specific capacities of 1671.3 and 504.6 mA h g⁻¹ at current densities of 0.1 A g⁻¹ and 3 A g⁻¹, respectively; capacity retention of 83.8% and specific capacity > 420 mA h g⁻¹ at 3 A g⁻¹ after 2000 cycles for LIBs.