Construction and electrochemical energy storage performance of FeS2@rGO-H/S

Abstract

Lithium-Sulphur (Li-S) batteries were one of the most promising batteries for large-capacity energy storage and electric vehicles. However, the shuttle effect of polysulfide lithium, the volume expansion and the poor electrical conductivity of sulfur in the process of charge and discharge restricted its application. In this paper, the authors constructed a composite of FeS₂@rGO-H as the carrier of sulfur. XRD, Raman, XPS SEM and BET analyses were used to characterize the obtained samples. The results showed that the prepared reduced graphene (rGO-H) obtained by the hydrazine hydrate and hydrothermal reduction method had a very high degree of reduction, which helped to accelerate the rapid transport of lithium ions in the positive sulfur electrode. And the FeS₂ fixed on rGO-H could inhibit the “shuttle effect” of polysulfide lithium and improved the cycling performance of sulfur positive electrode. Thus, the obtained composite FeS₂@rGO-H/S exhibited excellent electrochemical properties: its initial discharge capacity was up to 1529.2mAh/g at 0.1C, which was 91 % of the theoretical specific capacity of S. Even at a high rate of 5C, it still had a reversible discharge capacity of 629.9mAh/g. After 200 cycles at 1C, the discharge capacity attenuated from 1037.3 to 784.7mAh/g.