Self-doped N Sponge Carbon as a functional interlayer for high-performance lithium-sulfur batteries

Lithium-sulfur batteries is regarded as one of the most promising battery systems for the next generation because of its high energy density , low cost and environmental friendliness. However, the high solubility of long-chain polysulfides leads to low active sulfur utilization and strong shuttle effect, resulting in a rapid decline in battery capacity and poor cycle performance, which seriously hinders the practical application of lithium-sulfur batteries (LSB). In this work, we devised a simple method to prepare N-doped Sponge Carbon (SC), which has a rich three-dimensional connection structure, high electronic conductivity, and reasonable N-doped composition. Applied as the interlayer of lithium-sulfur batteries, the N-doped Sponge Carbon (SC) can adsorb long-chain LiPSs dissolved in the electrolyte and accelerate the conversion of long-chain LiPSs to short-chain ones, thereby realizing the secondary utilization of dissolved active sulfur and inhibiting the shuttle effect. Therefore, the lithium-sulfur batteries with a supplemental interlayer provided a large reversible capacity of 834.27 mAh g −1 at 0.5 C and maintained the high specific capacity of 804.9 mAh g −1 after 100 cycles, the capacity attenuation rate was as low as 0.035% per cycle. In addition, when the rate increased to 2 C, the discharge-specific capacity of 618.18 mAh g −1 can still be obtained. Most importantly, this Sponge Carbon interlayer may be of great significance for the commercial application of the high-performance lithium-sulfur batteries.