Prussian blue coated with reduced graphene oxide as high-performance cathode for lithium–Sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries with their outstanding theoretical energy density are strongly considered to take over the post-lithium ion battery era; however, they are limited by sluggish reaction kinetics and the severe shuttling of soluble lithium polysulfides. Prussian blue analogues (PBs) have demonstrated their efficiency in hindering the shuttle effects as host materials of sulfur; unfortunately, they show an inferior electronic conductivity, exhibiting considerable lifespan but poor rate performance. Herein, we rationally designed a PB@reduced graphene oxide as the host material for sulfur (S@PB@rGO) hybrids via a facile liquid diffusion and physical absorption method, in which the sulfur was integrated into Na₂Co[Fe(CN)₆] and rGO framework. When employed as a cathode, the as-prepared hybrid exhibited excellent rate ability (719 mA h g⁻¹ at 1C) and cycle stability (918 mA h g⁻¹ at 0.5C after 100 cycles). The improved electrochemical performance was attributed to the synergetic effect of PB and conductive rGO, which not only enhanced the physisorption of polysulfides but also provided a conductive skeleton to ensure rapid charge transfer kinetics, achieving high energy/power outputs and considerable lifespan simultaneously. This study may offer a new method manufacturing high performance Li–S batteries.