Activated and carbonized metal-organic frameworks for improved cycle performance of cathode material in lithium-sulphur batteries

The development of new battery systems has been intensively pursued in an effort to increase energy densities. Lithium-sulphur batteries represent a group of next-generation batteries with high theoretical capacity and energy density. The electrochemical properties of lithium-sulphur batteries may be improved by the application of appropriate conductive and porous additives to sulphur in the cathode material. Recently, materials belonging to the group of metal-organic frameworks (MOFs) have been widely investigated as host materials for sulphur thanks to their unique porous structure. In this work, various types of MOFs (GaTCPP, MOF-76(Gd), MIL-101(Fe)-NH2) were applied to the cathode material. MOFs were activated or carbonized before cathode material preparation. The structure of activated GaTCPP showed the lowest capacity fading per cycle (0.07 %) from activated MOFs during cycling at 0.5 C for 200 cycles. The carbonization process may improve the electrochemical properties of the electrode material. The best electrochemical properties showed carbonized MOF-76(Gd), and the capacity fading rate per cycle was only 0.04 % despite 200 cycles at 0.5 C.