Realizing High‐Performance Li/Na‐Ion Half/Full Batteries via the Synergistic Coupling of Nano‐Iron Sulfide and S‐doped Graphene

Iron sulfide (FeS) anodes are plagued by severe irreversibility and volume changes that limit cycle performances. Here, a synergistically coupled hybrid composite, nanoengineered iron sulfide/S‐doped graphene aerogel, was developed as high‐capacity anode material for Li/Na‐ion half/full batteries. The rational coupling of in situ generated FeS nanocrystals and the S‐doped rGO aerogel matrix boosted the electronic conductivity, Li+/Na+ diffusion kinetics, and accommodated the volume changes in FeS. This anode system exhibited excellent long‐term cyclability retaining high reversible capacities of 422 (1100 cycles) and 382 mAh g−1 (1600 cycles), respectively, for Li+ and Na+ storage at 5 A g−1. Full batteries designed with this anode system exhibited 435 (FeS/srGOA||LiCoO2) and 455 mAh g−1 (FeS/srGOA||Na0.64Co0.1Mn0.9O2). The proposed low‐cost anode system is competent with the current Li‐ion battery technology and extends its utility for Na+ storage. Glass half/full: Iron sulfide nanoparticles interlaced in an S‐doped graphene oxide aerogel show high reversible capacity with long‐term cycling when utilized as Li/Na‐ion anode. The synergistic effects of nanostructuring and the inclusion of polar S atoms in rGO aerogel encapsulation lead to enhanced conductivity, ion diffusion kinetics, and effective accommodation of volume expansion during cycling. The potential practical application of this facile hybrid composite approach is also demonstrated through Li/Na‐ion full cells.