PBDT-[(Bn)mim][TFSI]-LiTFSI Membranes: A New and Effective Solid Molecular Ionic Composite Electrolyte for Li-Ion Batteries

Solid electrolytes in Li-ion batteries offer enhanced safety and stability and contribute to improved energy density. In this study, a novel approach to synthesize a solid molecular ionic composite as an electrolyte for Li-ion batteries using 1-benzyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [(Bn)mim][TFSI] ionic liquid as the principal component, a rigid polymer poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), and LiTFSI salt was explored. The composition of the membrane was systematically varied, with the percentage of polymer fixed at 10%, while the percentages of ionic liquid and LiTFSI salt were modified. The electrochemical performance of the resulting membranes was evaluated. Remarkably, the membrane containing 10% polymer, 10% LiTFSI salt, and 80% ionic liquid demonstrated exceptional electrochemical properties with a capacity of 150 mAh/g in LFP-Li half-cell, closing the theoretical capacity of LiFePO₄. This membrane exhibited high conductivity and excellent stability, making it a promising candidate for use as an electrolyte in Li-ion batteries. The findings of this study provide valuable insights into the design and optimization of polymer-based electrolyte membranes for advanced energy storage applications.