Rechargeable Li-ion batteries have been extensively investigated for high power applications such as hybrid electric vehicles (HEV) and electric vehicles (EV). In order to develop better HEVs and EVs, it is essential to develop electrodes with higher rate capability. Nanostructured electrodes are seemingly the most promising candidate to improve the rate capability due to the short diffusion length and the large surface-to-volume ratio that allows for a large-area electrode/ electrolyte contact.

Nano-sized nickel oxides (NiO) have been widely studied as anode materials since they were first reported by Tarascon’s group. However, the improvement of rate capability is still limited by the above mentioned efforts.

Researchers of Lanzhou University and Lanzhou Institute of Chemical Physics of the CAS have fabricated nanostructured NiO electrodes using a simple thermal oxidation approach at a temperature as low as 400℃ in air. The nanostructured NiO electrode shows excellent rate capability and high capacity when used as an anode in lithium-ion batteries. The NiO electrode can deliver a capacity higher than 375 mA h g-1 even at a rate as high as 10C. More importantly, after the cycles at high rates, the electrode can resume its original capacity of about 717 mA hg^-1. The nanostructure and intrinsic close contact between the anode and the embedded current collector have been proven to be a favorable solution to improve the rate capabilities of lithium-ion battery anodes.

The work was financially supported by the National Natural Science Foundation of China and the Fundamental Research Funds for the Central Universities of China.

The detailed report has been published in J. Mater. Chem. (J. Mater. Chem., 2011, 21, 3571–3573).

J. Mater. Chem. Paper

(a) XRD patterns of the Ni foam before and after oxidation at 400℃ in air. (b) SEM images of Ni foam before oxidation. (c) and (d) SEM images of Ni foam after oxidation at 400℃ in air.