Effect of activator on preparation of coal-based porous carbon and its application in lithium-sulfur battery

As a non-metallic mineral with a wide range of sources, coal is an ideal raw material for the preparation of porous carbon. A porous carbon was prepared by 1/3 coking coal as raw material using NaOH and KOH as activators, and the specific electrochemical properties of sulfur/porous carbon composite cathode material were analyzed. The results show that the porous carbon prepared by the activation of NaOH or KOH alone has a specific surface area of 1 649 m²/g and 1 867 m²/g, respectively. The specific surface area of porous carbon activated by the mixture of NaOH and KOH is greatly reduced. When the mass ratio of NaOH to KOH is 1:1, the specific surface area of porous carbon is least which is 290 m²/g. The electrical properties of sulfur/porous carbon composite cathode material activated by 1:1 mass fraction of NaOH to KOH mixed activation are better than other cathode materials activated by NaOH and KOH respectively. The first discharge capacity is 790 mA·h/g at 0.2 C and the coulombic efficiency is 93.16%. The discharge capacity is as high as 740 mA·h/g after 100 cycles. The effect of coal-based porous carbon pore size distribution on electrochemical performance was also analyzed.