Achieving Optimum Performance Of Li-S Batteries
- Ramaprabhu S Department of Physics
With more and more utility being packed onto smaller devices and for longer periods of activity, improving the energy density of batteries has taken centre stage among the most sought after research topics in the field of energy storage and efficiency. Lithium-ion batteries have been explored extensively for this purpose as they deliver a much higher energy density than other rechargeable batteries in current use. While they certainly have immense potential to improve energy storage, there are many other obstacles that need to be overcome, to enable the commercialization of Li-S batteries.
Dr. Ramaprabhu and team have mitigated some of these obstacles by modifying the cathode significantly, with the use of partially exfoliated multi-walled carbon nanotubes (PECNT) as a sulphur host. This largely increases the available surface area and pore volume while also providing active sites for the Li+ ions, electrons, and the diffusion of electrolytes. The partial oxidation and subsequent reduction of multi-walled carbon nanotubes enhance the specific surface area by unravelling some of the outer graphene nanoribbons while keeping the core intact, and conductivity undiminished. While this approach minimises the shuttling of LPS by physical confinement, the interaction between carbon and LPS is weak. Another approach the team has employed is to insert a GCN-GDL (graphitic Carbon Nitride-gas diffusion layer) interlayer between the separator and cathode. Graphitic Carbon Nitride is obtained upon polymerisation of melamine. This immobilises LPS through chemisorption due to the polar nitrogen sites in GCN. This GCN addition has been made to the gas diffusion layer (GDL), which is used in fuel cells as a backing layer for the catalyst.