Revolutionary Nanostructured Lithium - Sulphide Batteries: Delivers High Power

A research team led by Prof. Linda Nazar from University of Waterloo has demonstrated for the first time the outstanding performance of the lithium sulphur battery. The team has shown that the Li-S battery can store and deliver more than three times the power of conventional Li-ion batteries. This finding has been reported in the June 2009 issue of the journal "Nature Materials". The rechargeable battery market is expanding at an exponential rate due to the massive demand for portable devices like laptops, cellular mobile phones, PDAs, hybrid electric vehicles, etc. In order to meet this demand, worldwide efforts are being targeted to develop a battery that has the highest energy density, large safety factor and longest life in terms of discharge cycles and ease of maintenance, while still being environmentally friendly.

The Li-S battery represents a dramatic advance over the state - of - the art Li-ion battery in several respects: i.e. energy density, safety, rate capability and cost. However, one of the difficult challenges in the case of Li-S battery is to maintain an intimate contact between the electrically insulating sulphur and a conductor such as carbon to enable a reversible electrochemical reaction to occur at a high current rate. Prof. Linda Nazar and her colleagues have come up with a leapfrog nanotech solution to address this issue.

Currently, the cathode of Li-S battery is designed based on various carbon-sulphur materials; however, none of these materials are able to provide an intimate contact between Li and S to ensure smooth electron flow. The new approach adopted by the group at University of Waterloo uses carbon in the nanostructured mesoporous form and sulphur is encapsulated within the nanopores of carbon. This novel strategy provides an intimate contact between sulphur and carbon, essentially with a much larger surface area for effecting electron exchange than has been achieved in the past.

This nanostructured composite can provide reversible capacities up to 1320 mAhg-1, which is far greater than 300-500 mAhg-1 achieved in the conventional Li-S batteries. (06/10/2009)