FeS2 Nanoparticles Encapsulated in S/N Co-Doped Carbon Nanofibers With a Three-Dimensional Multi-Channel Structure for Lithium-Ion Batteries

Abstract

Pyrite (FeS2) is one of the potential candidates for advanced rechargeable Li-ion batteries (LIBs) owing to its inherent capacity (849 mAh g−1), environmental friendliness, and abundant natural resources. However, the volume expansion of FeS2 and the dissolution of polysulfide in the electrochemical reaction severely limit its application in the field of energy conversion and storage. Herein, FeS2 nanoparticles are encapsulated in S/N co-doped three-dimensional multi-channel structural carbon nanofibers (FeS2@CNFs) through the electrospinning method. As a cathode material for LIBs, FeS2@CNFs demonstrated excellent rate property and cyclic stability. The 3FeS2@CNFs (weight ratio of FeS2 is 30%) present the initial capacity of 1,336.7 mAh g−1 and the remaining 856.5 mAh g−1 at 0.02A g−1 after 100 circles. The favorable electrochemical properties have confirmed that carbon nanofibers can enhance the electroconductivity of electrodes, reduce the volume collapse of FeS2, and remit the dissolution of polysulfide during the Li+ ions insertion/de-insertion process. In addition, co-doped S/N can supply abundant active sites for electrochemical reactions, providing enough space for Li+ ion storage. The results indicate that 3FeS2@CNFs is a cathode with a developmental prospect for LIBs.