Porous Carbon Interlayer Derived from Traditional Korean Paper for Li–S Batteries

A carbonized interlayer effectively helps to improve the electrochemical performance of lithium-sulfur (Li-S) batteries. In this study, a simple and inexpensive carbon intermediate layer was fabricated using a traditional Korean paper called "hanji". This carbon interlayer has a fibrous porous structure, with a specific surface area of 91.82 m² g^-1 and a BJH adsorption average pore diameter of 26.63 nm. The prepared carbon interlayer was utilized as an intermediary layer in Li-S batteries to decrease the charge-transfer resistance and capture dissolved lithium polysulfides. The porous fiber-shaped carbon interlayer suppressed the migration of polysulfides produced during the electrochemical process. The carbon interlayer facilitates the adsorption of soluble lithium polysulfides, allowing for their re-utilization in subsequent cycles. Additionally, the carbon interlayer significantly reduces the polarization of the cell. This simple strategy results in a significant improvement in cycle performance. Consequently, the discharge capacity at 0.5 C after 150 cycles was confirmed to have improved by more than twofold, reaching 230 mAh g^-1 for cells without the interlayer and 583 mAh g^-1 for cells with the interlayer. This study demonstrates a simple method for improving the capacity of Li-S batteries by integrating a functional carbon interlayer.