Experimental and Theoretical Analysis of Synthesized Poly(Pthalazinone Ether Sulfone Ketone) Copolymer‐Modified Separators for Li−S Batteries

Abstract

AbstractLithium‐Sulfur (Li−S) batteries have become an undoubtful choice for future high‐energy applications due to their high theoretical capacity and energy density. However, the “Shuttle Effect” is a phenomenon that hinders the practical application of Li−S batteries. The present work reports a facile synthesis of poly(phthalazinone ether sulfone ketones) (PPESK) as a surface modifier for the conventional glass fiber separator to arrest the shuttle effect. PPESK is prepared by aromatic nucleophilic substitution (SNAr) with 4‐(4‐hydroxyphenyl) phthalazin‐1(2H)‐one, bis (4‐chlorophenyl methanone), and 4,4′‐sulfinyl‐bis (chlorobenzene). The Li−S cells with PPESK@GF separators deliver a high initial discharge capacity of 1054.2 mAh g−1 at 0.2 C than GF (991.5 mAh g−1 at 0.2 C). Density functional theory (DFT) calculations are performed to determine the interaction between the PPESK with lithium polysulfides, Li2Sn (n=1, 2, 4, 6, and 8). The results indicate that all the lithium polysulfides strongly bind with the sulfone nitrogen site of the PPESK structure with high binding energy, particularly Li2S6 has −492.58 kcal/mol. The atoms‐in‐molecules analysis (AIM) shows the presence of ionic bonds between PPESK and lithium polysulfides. Gibb's free energy, the thermodynamical parameter, indicates that the reaction is exergonic and spontaneous. Overall, the theoretical findings augment the observed experimental results.