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

The polysulfide shuttle effect and slow liquid-solid conversion are supposed to be the main bottlenecks limiting lithium-sulfur battery practicality. Although a great deal of research has been devoted to the nucleation and transformation kinetics of polysulfides, many implicit details cannot be captured. In this work, we design a conducting network, FeN x -NPC, derived from hemin, and induce a 3D nucleation mode. Different from the control group with the 2D nucleation mode, a higher Li 2 S deposition and earlier nucleation are observed. Here, in situ impedance is applied to further understand the potential relationship between nucleation mode and liquid-solid transformation, and DRT results from impedance data are systematically compared from two aspects: (1) single battery under different voltages and (2) different batteries under the same voltage. It reveals that the 3D nucleation mode ensures more growth sites, on which a covered thin Li 2 S layer exhibits no charge transfer limitation. What is more, the porous structure with 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 mA h g -1 at 5 C).