Ultramicroporous Carbon through an Activation-Free Approach for Li–S and Na–S Batteries in Carbonate-Based Electrolyte

We report an activation-free approach for fabricating ultramicroporous carbon as an accommodation of sulfur molecules for Li–S and Na–S batteries applications in carbonate-based electrolyte. Because of the high specific surface area of 967 m 2 g –1, as well as 51.8% of the pore volume is contributed by ultramicropore with pore size less than 0.7 nm, sulfur cathode exhibits superior electrochemical behavior in carbonate-based electrolyte with a capacity of 507.9 mA h g –1 after 500 cycles at 2 C in Li–S batteries and 392 mA h g –1 after 200 cycles at 1 C in Na–S batteries, respectively.