A new production method may bring the commercialisation of lithium-sulphur batteries closer. Thanks to the method, lithium-sulphur batteries are able to hold their capacity for over 200 charge and discharge cycles, removing one of the main obstacles to their use.
The method was developed by NanoBio Lab (NBL) of the Singapore Agency for Science, Technology and Research (A*STAR). Lithium-ion batteries are currently widely used to power modern devices. These include laptops and mobile phones. However, the technology has limited storage capacity and also has risks due to its electrochemical instability.
Lithium-sulphur batteries
Lithium-sulphur batteries are an alternative to lithium-ion batteries. Among other things, the higher storage capacity, low production costs and availability of necessary materials make lithium-sulphur batteries interesting. For instance, the batteries are theoretically capable of storing up to 10 times more energy than lithium-ion batteries; where a lithium-ion cathode has an energy storage capacity of 140 mAh/g, this is 1,220 mAh/g for a sulphur-ion cathode of NBL.
At the same time, however, these batteries also have their limitations. For instance, lithium-sulphur batteries have so far been unable to maintain their capacity during repeated charge and discharge cycles. This is due to the construction of a lithium-sulphur cathode, which uses a carbon 'host'. This host collapses during the initial charge and discharge cycle, causing a structural change in the cathode. As a result, conventional cathodes acquire a high density and are compact with a smaller surface area and smaller pores. The performance of the battery decreases as a result.
Maintaining capacity longer
The lithium-sulphur cathodes developed by NBL are able to retain their capacity for a longer period of time. This is possible thanks to the production method used by the Singaporean company. NBL's cathodes reportedly offer 48% higher capacity than conventional lithium-sulphur cathodes. They also lose 26% less capacity during charge and discharge cycles than their conventional counterparts.
"We are at a tipping point in energy research. It is becoming increasingly difficult for current battery technologies to keep up with the rising demand for energy storage. From portable electronics to electric vehicles and power grids, innovative energy storage solutions are required to meet the needs created by increasing electrification and realise the vision for renewable energy," NBL writes on its website. "In our lab, we are developing nanocomposites with controlled porosity and architecture to improve battery performance. Specifically, we are working on lithium-ion, lithium-sulphur and solid-state battery technologies."
Author: Wouter Hoeffnagel
