CO₂-Derived Hierarchical Porous Carbon Electrode and Interlayer Doped with Nitrogen for Lithium-Sulfur Battery

Shuttle phenomena of lithium polysulfides (LiPSs) in lithium sulfur (Li-S) batteries is a serious obstacle to commercialization of Li-S battery. Various studies are being conducted to mitigate the shuttle effect, but among them, the approach using an interlayer has been introduced. This study proposes a hierarchical carbon material for both carbon cathode composite and interlayer synthesized from gaseous carbon dioxide. The highly porous carbon material used as a cathode enables a homogeneous distribution of active materials such as sulfur without agglomeration and allows rapid diffusion of ions. In addition, the interlayer made in this study is 30wt% lighter than the existing fiber-type paper layer based on its high porosity and at the same time has a very high 15.5% nitrogen atoms. Excess N atoms including pyridinic-N and pyrrolic-N contained in the interlayer prevent diffusion of LiPSs to the counter electrode through strong chemical bonds with LiPSs, and also greatly improve conductivity, minimizing resistance related to charge transfer. As a result, the cells assembled with them maintain a capacity of 700 mAh g−1 after 500 cycles at 0.5 C. In addition, it can exhibit a capacity of 697 mAh g−1 even at a high current density of 7.0 C.