Sputtered nickel oxide on vertically-aligned multiwall carbon nanotube arrays for lithium-ion batteries

We fabricated nickel oxide (NiO) on vertically-aligned multiwall carbon nanotube (MWCNT) arrays (MWCNT/NiO) as an electrode for lithium-ion batteries. The specific capacity of 864.8 mA h g−1 at the rate of 143.6 mA g−1 for up to 50 cycles was achieved. Compared to the electrode based on NiO thin film on stainless steel, the MWCNT/NiO showed significant improvements because the vertically-aligned MWCNT arrays enabled easy ion and electron transport and acted as excellent base-structures that minimize pulverization of the active materials by absorbing the compressive and tensile stresses during charge and discharge processes. Electrochemical impedance spectroscopy of MWCNT/NiO showed low internal resistance and low charge-transfer resistance of the MWCNT/NiO that suggest superior ion and electron transport, respectively. This demonstrated that the vertically-aligned MWCNT array is a promising current collector for conversion-type active materials.