Pyrolyzed pencil graphite coated cellulose paper as an interlayer: An effective approach for high-performance lithium-sulfur battery

Lithium-sulfur (Li-S) battery is next generation battery technology but it’s commercialization is obstructed primarily due to the shuttling effect of lithium polysulfides (LiPSs). Herein, we report an effective approach using pencil coated pyrolyzed cellulose filter paper as an interlayer to suppress the LiPSs dissolution into the electrolyte and thus allowing effective utilization of active sulfur cathode. Here, the binder clay particles (mainly SiO2) of pencil graphite facilitate the adsorption of LiPSs, whereas graphite increases the electrical conductivity and acts as a physical barrier to LiPSs. To investigate further, we utilize three different grades of pencil (4B, HB, 5H) which vary in terms of clay (SiO2) composition. It is observed that the HB pencil coated interlayer has the right balance of silica and graphite, which results in an impressive initial capacity of 1352 and 995 mAh g−1 at the current density of 0.1 and 0.5 A g−1, respectively. The cell exhibit high cycling stability of 900 mAh g−1 at 1 A g−1 (3.0 C) for 350 cycles with a slow capacity decay of 0.07% per cycle. The phenomenon of LiPSs adsorption is further understood using post-cycling analysis, H-cell adsorption testing, and shuttle factor calculation for the development of commercial Li-S batteries.