Three-dimensional porous carbon decorated with FeS 2 nanospheres as electrode material for electrochemical energy storage

The large volume variation and decomposition of pyrite iron sulfide (FeS 2 ) during the charge/discharge process are still a big issue limiting its application as electrode material for electrochemical energy storage. Herein, three-dimensional porous carbon (3DPC) decorated with FeS 2 nanospheres nanocomposites (FeS 2 /3DPC) are developed as electrode material for supercapacitors and sodium ion batteries (SIBs) through a facile hydrothermal approach. The FeS 2 /3DPC nanocomposites demonstrate much better electrochemical energy storage performances than pure FeS 2. The 50 %FeS 2 /3DPC (FeS 2 content at 50% weight percent) shows an outstanding specific capacitance of 304F g −1 at 2 A g −1. Moreover, the 50 %FeS 2 /3DPC as anode for Na + /Na half cell presents a high specific capacity of 770.3 mAh g −1 at 0.02 A g −1, and shows a remarkable rate performance and cyclic stability. The results prove that 3DPC as FeS 2 substrate can not only improve the conductivity of electrode material, but also effectively inhibit the volume collapse of FeS 2. The as-designed embedded structure and the synthesis technology should have a promising prospect for applying in electrochemical energy storage.