The team grew ultralong TiO₂-based nanotubes from TiO₂ nanoparticles using a stirring hydrothermal method. Their study confirmed that the mechanical-force-driven stirring process is the reason for the lengthening of the nanotubes.

In their paper, they note that this protocol to synthesize elongated nanostructures can be extended to other nanostructured systems, opening up new opportunities for manufacturing advanced functional materials for high-performance energy-storage devices.

Titanium dioxide (TiO₂) nanomaterials are of interest as Li-ion anode materials due to their advantages in terms of cost, safety, and rate capability. A 2013 paper (Dylla et al.) by a team from the University of Texas at Austin noted that of the most studied polymorphs, nanostructured TiO₂(B) has the highest capacity with promising high rate capabilities.

However, they noted a number of disadvantages as well. Titania in general suffers from poor electronic and ionic conductivity. Although nanostructuring can help alleviate problems with poor ionic conductivity by shortening lithium diffusion pathways, this also increases the likelihood of severe first discharge irreversible capacity loss. Nanostructuring also results in lowered volumetric energy density, which could be a considerable problem for mobile applications.

Moving forward, Prof Chen’s research team will be applying for a Proof-of-Concept grant to build a large-scale battery prototype. The technology is currently being licensed to a company. Prof. Chen expects that a new generation of fast-charging batteries will hit the market in two years.

With our nanotechnology, electric cars would be able to increase their range dramatically with just five minutes of charging, which is on par with the time needed to pump petrol for current cars. Equally important, we can now drastically cut down the waste generated by disposed batteries, since our batteries last ten times longer than the current generation of lithium-ion batteries.

—Prof. Chen

This battery research project took the team of four NTU Singapore scientists three years to complete and is funded by Singapore’s National Research Foundation.

Resources

• Tang, Y., Zhang, Y., Deng, J., Wei, J., Tam, H. L., Chandran, B. K., Dong, Z., Chen, Z. and Chen, X. (2014), “Nanotubes: Mechanical Force-Driven Growth of Elongated Bending TiO₂-based Nanotubular Materials for Ultrafast Rechargeable Lithium Ion Batteries,” Adv. Mater., 26: 6046 doi: 10.1002/adma.201470238

• Anthony G. Dylla, Graeme Henkelman and Keith J. Stevenson (2013) “Lithium Insertion in Nanostructured TiO₂(B) Architectures,” Accounts of Chemical Research doi: 10.1021/ar300176y