Coaxial-nanostructured MnFe₂O₄ nanoparticles on polydopamine-coated MWCNT for anode materials in rechargeable batteries

MnFe₂O₄@PDA-coated MWCNT coaxial nanocables are successfully designed via a simple one-pot process by utilizing the adhesion property of polydopamine (PDA) with cations in aqueous solutions and employing a modified co-precipitation synthesis at a low temperature. The incorporation of the PDA coating layer on the MWCNT leads to the well-dispersed state of the MWCNTs in the aqueous solution due to the hydrophilic functional group of the PDA coating layer. In addition, the catechol-based functional group of the PDA coating layer effectively anchors the Mn and Fe ions from the aqueous solution before the co-precipitation process, eventually resulting in the preferential and homogeneous formation of MnFe₂O₄ nanoparticles on the MWCNT. The final MnFe₂O₄@PDA-coated MWCNT electrode exhibits excellent power characteristics such as a high rate capacity of around of 367 mA h g^-1 at a 5C-rate condition (= 4585 mA g^-1). Cycling tests reveal that the stable performance of the MnFe₂O₄@PDA-coated MWCNT electrode persists even after 350 cycles.