Rational synthesis of two-dimensional G@porous FeS2@C composite as high-rate anode materials for sodium/potassium ion batteries

Pyrite (FeS2) with the advantages of high capacity, low cost and environmental benign has been considered as a promising anode material for alkali metal (Li, Na, K) ion batteries. However, the large volume expansion and its semiconductor nature result in poor battery performance and hamper its practical applications. To overcome these drawbacks, we rationally construct a two-dimensional FeS2- carbon architecture, from which porous FeS2 nanoparticles are distributed within reduced graphene oxide matrix and carbon coating shell with abundant interior void space. Benefiting from its structure properties with conductive carbon network, protective carbon layer, and interior void room, as-prepared rGO@p-FeS2@C composite displays superior electrochemical performance as anode materials for sodium/potassium ion batteries. For sodium storage, it exhibits good cyclic performance with a high capacity 598 mA h g(-1) sustained after 100 cycles at 0.1 A g(-1), and excellent rate capability (428 mA h g(-1) at 10 A g(-1)). For potassium storage, it also maintains a superior rate capacity of 298 mA h g(-1) at 2 A g(-1). Moreover, pseudocapacity has been proved to be dominated in charge/discharge process, accounting for the excellent rate performance. (C) 2019 Elsevier Ltd. All rights reserved.