Synergistic Effect between Monodisperse Fe<sub>3</sub>O<sub>4</sub> Nanoparticles and Nitrogen-Doped Carbon Nanosheets to Promote Polysulfide Conversion in Lithium–Sulfur Batteries
Min‐Hui Li, Shan Ji, Xianguo Ma, Hui Wang, Xuyun Wang, Vladimir Linkov, Rongfang Wang
Abstract
Effective fabrication of electrocatalysts active in anchoring and converting lithium polysulfides is critical for the manufacturing of high-performance lithium–sulfur batteries (LSBs). In this study, original Fe3O4 nanospheres with diameters close to 12 nm were finely dispersed over a porous nitrogen-doped carbon matrix by the freeze-drying method to produce a three-dimensional composite material (nano-Fe3O4/PNC) suitable for application as a sulfur host in LSBs. Nano-Fe3O4/PNC loaded with sulfur (S@nano-Fe3O4/PNC) was used as a cathode in a Li–S cell, whose initial discharge specific capacity reached 1256 mA h g–1 at a 0.1 C rate. After 100 charge–discharge cycles at a 0.2 C rate, the reversible capacity of S@nano-Fe3O4/PNC remained at 745 mA h g–1, demonstrating a capacity retention rate of 70%. Importantly, a high Coulombic efficiency of more than 99% was achieved, indicating effective inhibition of the polysulfides’ “shuttle effect” by nano-Fe3O4/PNC. The use of electrolytes containing lithium nitrate further reduces the “shuttle effect” of polysulfides. This study demonstrates the synergistic effect between metal oxide nanoparticles and N-doped carbon, which plays an important role in promoting the adsorption and conversion of polysulfides in LSBs.