Facile synthesis of NiCo2O4nanorod arrays on Cu conductive substrates as superior anode materials for high-rate Li-ion batteries

Abstract

In this work, we report a mild and cost-effective solution method to directly grow Ni-substituted Co₃O₄ (ternary NiCo₂O₄) nanorod arrays on Cu substrates. Electrochemical impedance spectroscopy (EIS) measurements show that the values of the electrolyte resistance R_e and charge-transfer resistance R_ct of NiCo₂O₄ are 6.8 and 63.5 Ω, respectively, which are significantly lower than those of binary Co₃O₄ (10.4 and 122.4 Ω). This EIS characterization strongly confirms that the ternary NiCo₂O₄ anode has much higher electrical conductivity than that of the binary Co₃O₄ electrode materials, which should greatly enhance the lithium storage performances. Due to the well-aligned 1D nanorod microstructure and a higher electrical conductivity, these ternary NiCo₂O₄ nanorod arrays manifest high specific capacity, excellent cycling stability (a high reversible capacity of about 830 mA h g⁻¹ was achieved after 30 cycles at 0.5 C) and high rate capability (787, 695, 512, 254, 127 mA h g⁻¹ at 1 C, 2 C, 6 C 50 C and 110 C, respectively).