Posted: August 9, 2007

Window into nanospace could boost batteries

(Nanowerk News) Investigating how nickel hydroxide crystals grow in nanospace could lead to improved performance of rechargeable batteries, say scientists in Japan "Crystal formation and growth during the hydrothermal synthesis of β-Ni(OH)2 in one-dimensional nano space").
Hironori Orikasa and colleagues at Tohoku University, Sendai, have grown nickel hydroxide nanorods inside carbon nanotubes. For the first time, the researchers were able to actually watch the rods forming using transmission electron microscopy (TEM).
Nickel hydroxide is used as a potential electrode in rechargeable batteries. Nanoscale control is crucial for improving the performance and lifetime of the electrodes. 'We have demonstrated the effectiveness of carbon-coated nanochannels as a reaction field for the hydrothermal synthesis of inorganic nano crystals with controlled size and shape,' said Orikasa.
nickel hydroxide nanorods inside carbon nanotubes
Watching crystals grow could lead to better rechargable batteries
Nanochannels need to be durable, uniform and thin enough so that TEM can be used to look inside the tubes to see the crystals growing. Only the carbon-coated anodic aluminium oxide channels developed by these scientists currently meet all these requirements.
By watching the crystal formation in the nanotubes, the team discovered that normal hexagonal crystals of nickel hydroxide form until the crystal size becomes too large to fit within the tube. The crystals are forced to grow in the shape of the tube which surrounds them and so nickel hydroxide rods are made.
'This . indeed provides a smart route for controlled synthesis of nanocrystals confined within nanospace,' said Shu-Hong Yu, professor of materials science, University of Science and Technology of China, Hefei.
Angus Kirkland, a materials expert at the University of Oxford, UK, was also impressed by the team's 'significant achievement'.
'This is potentially a powerful method that will find application in the large scale synthesis of a range of nanoscale oxide materials with significant industrial potential,' said Kirkland.
Source: Chemical Science (Ruth Doherty)