Rapid synthesis of FeS nanoparticles encapsulated with nanoporous graphitic shells for high performance sodium- and lithium-ion batteries

FeS nanoparticles encapsulated with highly nanoporous graphitic shells were prepared via a S-template-approach. The template was in situ doped in the graphitic shells during fabricating the FeS@C core–shell nanoparticles via short-time floating catalytic pyrolysis (1–4 seconds) and then nanopores were significantly created by partially removing the S-doping structure in the shells. FeS encapsulated with the nanoporous graphitic shells could avoid the large volume change between the insertion and extraction of Na+, leading to good stability of the prepared FeS@PWS900 nanoparticles (after 500 cycles at a current density of 3 A g−1; specific capacity > 240 mA h g−1; capacity retention: 89.6%). Additionally, the high nanoporosity of the graphitic shells could offer more efficient diffusion channels and shorten the diffusion route for the fast distribution of the Na+/Li+, leading to the improved electrochemical performance of the FeS@PWS900 (772 mA h g−1 at a current density of 0.1 A g−1 and 340 mA h g−1 at 3 A g−1 for SIBs; 1426 mA h g−1 at 0.2 A g−1 and 1057 mA h g−1 at 3 A g−1 for LIBs).