A functional separator was developed for lithium (Li) metal batteries (LMBs) by coating a polyethylene (PE) substrate with a composite layer of lithiated sulfonated poly(ether ether ketone) (LSP) and corona-poled BaTiO 3 (BTO) nanoparticles. The sulfonic acid groups in LSP enabled effective anion repulsion, while the internal electric field induced by polarized BTO enhanced Li + selectivity. The BTO/LSP-3.5-based coating layer exhibited enhanced electrolyte wettability (contact angle of 13.2°) and high thermal dimensional stability (negligible shrinkage at 130 °C). Upon corona poling, the resulting PBTO/LSP-3.5 separator achieved a increased lithium-ion transference number ( t Li + = 0.66). This functional coating layer effectively suppressed dendritic Li growth and stabilized the electrode-electrolyte interface, leading to a stable overpotential in symmetric Li/Li cells and enhanced cycling performance in NCM811/Li cells, achieving 56.4% capacity retention after 200 cycles at 1C. Furthermore, the PBTO/LSP-3.5-coated separator maintained stable operation even after thermal shock at 120 °C, whereas cells with bare PE separators experienced immediate failure. These results highlight the potential of the PBTO/LSP-coated separator as a robust strategy to improve the safety and durability of high-energy-density LMBs. • Functional separator with poled BaTiO 3 and Li-SPEEK was successfully developed. • Internal electric field and anion repulsion synergetically regulated Li + flux. • High Li + transference number of 0.66 was achieved with the functional coating. • Li metal batteries showed 56.4% capacity retention after 200 cycles at 1C. • Stable battery operation was maintained even after thermal shock at 120 °C.
Park et al. (Tue,) studied this question.