Encapsulating yolk-shell FeS2@carbon microboxes into interconnected graphene framework for ultrafast lithium/sodium storage

Pyrite FeS2 has been accepted as one promising anode candidate for lithium- (LIBs) and sodium-ion batteries (SIBs) due to its extremely high theoretical capacity of 894 mAh g(-1). However, the practical capabilities including rate performance and cycling stability of FeS2-based materials are still restricted by exaggerated volume variation and sluggish ions kinetics. Herein, we upgrade an interesting dual-carbon decorated strategy to address these issues. The resultant material features a hierarchical architecture with yolk-shell FeS2@carbon microboxes as well as interconnected graphene framework (GF/FeS2@C). By virtue of the dual-carbon protection effect and binary channel for electrons/ions transfer, the GF/FeS2@C composites exhibit superior Li and Na storage performance. For LIBs, it shows superior rate capability of 428 mAh g(-1) at 20 A g(-1) and decent long-term cycle stability. As for SIBs, it delivers a reversible capacity of 200 mAh g(-1) at high current density of 10 A g(-1) and ultra-long lifespan at 0.5 A g(-1) (257 mAh g(-1) after 1000 cycles) and 2 A g(-1) (203 mAh g(-1) after 600 cycles). Such excellent high-rate capabilities delivered by the GF/FeS2@C feature the predominant fast charging properties for potential application in portable electric technology. (C) 2019 Elsevier Ltd. All rights reserved.