Lithium/sulfur (Li/S) batteries have been recognized as one of the most promising substitutes for current energy-storage systems due to their high-energy density and low cost. However, the high solubility of intermediate products (i.e., lithium polysulfides) and the resultant shuttle effect lead to a rapid capacity fading along with a low Coulombic efficiency, which hinders the practical application of Li/S batteries. Herein, polyethylenimine (PEI) polymer is applied as a polar binder in Li/S batteries to address above issues. The sulfur cathode with a high sulfur loading density of 8.6 mg/cm² coated by an ultrathin PEI layer (~ 6.9 nm) shows a high initial areal capacity of up to 9.7 mAh/cm². The capacity is still maintained at 6.4 mAh/cm² after 50 cycles, which is comparable to that of commercial Li-ion batteries. The excellent cycling performance is attributed to the presence of abundant amino groups in PEI polymer, which can strongly bond with the intermediate lithium polysulfides through electrostatic force and therefore suppress the shuttle effect, as revealed by in situ/operando ultraviolet-visible spectroscopy and S K-edge X-ray absorption spectroscopy. Our effective strategy of immobilizing lithium polysulfides by electrostatic force through a functional binder should be of great significance for the practical application of Li/S batteries.

锂/硫（Li / S）电池因其高能量密度和低成本而被公认为是当前储能系统最有希望的替代品之一。然而，中间产物（即，多硫化锂）的高溶解度和所得的穿梭效应导致快速的容量衰减以及低库仑效率，这阻碍了Li / S电池的实际应用。在本文中，聚乙烯亚胺（PEI）聚合物被用作Li / S电池中的极性粘合剂以解决上述问题。涂有超薄PEI层（〜6.9 nm）的高硫负载密度为8.6 mg / cm ²的硫阴极显示出高达9.7 mAh / cm ²的高初始面容量。容量仍保持在6.4 mAh / cm ²经过50次循环后，可与商用锂离子电池相媲美。优异的循环性能归因于PEI聚合物中存在丰富的氨基，它们可以通过静电力与中间的多硫化锂牢固地键合，因此抑制了穿梭效应，如原位/操作紫外可见光谱法和S K所揭示的那样。边X射线吸收光谱。我们通过功能性粘合剂通过静电力固定多硫化锂的有效策略对Li / S电池的实际应用具有重要意义。