Regulating Polysulfide Transformation and Deposition Kinetics in Lithium-Sulfur Batteries Based on 3D Conductive Framework

The polysulfide shuttle effect and slow liquid-solidconversionare supposed to be the main bottlenecks limiting lithium-sulfurbattery practicality. Although a great deal of research has been devotedto the nucleation and transformation kinetics of polysulfides, manyimplicit details cannot be captured. In this work, we design a conductingnetwork, FeN x -NPC, derived from hemin,and induce a 3D nucleation mode. Different from the control groupwith the 2D nucleation mode, a higher Li2S deposition andearlier nucleation are observed. Here, in situ impedance is appliedto further understand the potential relationship between nucleationmode and liquid-solid transformation, and DRT results fromimpedance data are systematically compared from two aspects: (1) singlebattery under different voltages and (2) different batteries underthe same voltage. It reveals that the 3D nucleation mode ensures moregrowth sites, on which a covered thin Li2S layer exhibitsno charge transfer limitation. What is more, the porous structurewith in situ-derived nanotubes favors Li+ faster diffusion.Hence, these advantages allow Li-S cells to deliver high capacity(about 1423 mA h g(-1) at 0.1 C), low capacity attenuation(0.029% per cycle at 2 C), and excellent rate performance (620 mAh g(-1) at 5 C).