Hierarchical Co3O4@multiwalled carbon nanotube nanocable films with superior cyclability and high lithium storage capacity

• One step electrophoretic deposition of hierarchical Co3O4@MWCNT nanocable films.
• The weight content and morphology of the Co3O4 sheath can be conveniently tuned.
• A micro-cathode induced coating mechanism can explain the formation of the nanocables.
• The hierarchical architecture leads to superior cyclability and high capacity.
• High capacity of 860 mAh g−1 is achieved at 1 C and no decay is found after 250 cycles.

Hierarchical Co3O4@multiwalled carbon nanotube (MWCNT) nanocable films are deposited on copper foils via a facile one-step electrophoretic deposition (EPD) from MWCNT suspension containing Co(NO3)2·6H2O and the subsequent heat treatment. The obtained films show network morphologies, with micro-/mesoporous Co3O4 sheath uniformly coated on the interconnected MWCNT core. By varying the mass ratios of Co(NO3)2·6H2O to MWCNTs in the suspension, a series of nanocable films are obtained with different Co3O4 sheath thickness, morphology, and mass content. Among them, the Co3O4@MWCNT-4 nanocable film, with a high surface area of 156 m2 g−1 and optimally hierarchical pore size distribution, proves to be a qualified candidate anode for lithium-ion batteries. The reversible capacity can reach as high as 1109 mAh g−1 at a relatively high current of 0.2 C (1 C = 890 mA g−1). At a higher current of 1 C, the reversible capacity can retain as high as 860 mAh g−1 and shows no obvious decay after 250 cycles.

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