Constructing a one-dimensional long-short hybrid carbon skeleton as separator modifier for dendrite-free Li-S batteries

The shuttling effect of polysulfides and the uncontrollable evolution of dendritic lithium, which occur individ-ually in each electrode, obstruct the development of lithium-sulfur (Li-S) battery in practical conditions. With the intention of exploring a simple integrated method to solve above-mentioned issues, one-dimension long-short carbon nanofiber-nanotube with rich active sites was prepared to construct 3D scaffold architecture as an effective modifier on the separator, developing a symmetrically modified separator with hierarchically porous Li+ channels. The weaving carbon nanofibers with vertically-rooted carbon nanotube tentacles are conducive to both long-range and short-range electric conduction. In addition, the 3D carbon nanofiber-nanotube structure can reduce the local current density and induce uniform lithium nucleation. Meanwhile, coexisting metallic nanoparticles and abundant doping systems act as the adsorptive and electrocatalytic sites to achieve high ef-ficiency in the processes of sulfur electrochemistry. Because of these advantageous characteristics, the Li-S cells based on the double-sided modified separator achieve reliable Li/S electrochemistry including a highly specific capacity of 1044.1 mAh g- 1 over 100 cycles at 0.2 C, an excellent rate performance of up to 3 C, as well as an areal capacity of up to 4.38 mAh cm-2 under increased sulfur loading of 5.5 mg cm-2. Moreover, the Li-S pouch cell using this symmetric separator modification strategy exhibits excellent cycling stability, demonstrating broad application prospects in the flexible energy storage area.