Multifunctional V 3 S 4 -nanowire/graphene composites for high performance Li-S batteries
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Published online 13 May 2020 | https://doi.org/10.1007/s40843-020-1313-6
Multifunctional V3S4-nanowire/graphene composites for high performance Li-S batteries 1
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Tianyu Tang , Teng Zhang , Lina Zhao , Biao Zhang , Wei Li , Junjie Xu , Tao Li , Long Zhang , 2 1* Hailong Qiu and Yanglong Hou ABSTRACT Lithium sulfur (Li-S) batteries have been regarded as a promising next-generation energy storage system with high theoretical specific capacity and energy density, but still facing challenges. In order to make Li-S batteries more competitive, combination of trapping sites and electrocatalytic properties for polysulfides is an effective way to improve the battery performance. In this study, we prepare a type of multifunctional V3S4-nanowire/graphene composites (V3S4G) by uniformly dispersing V3S4 nanowires on the graphene substrate. This structure contributes to the sufficient exposure of multifunctional V3S4 active sites which can anchor polysulfides and accelerate reaction kinetics. Thus, the Li-S batteries based on the multifunctional V3S4-G sulfur cathode deliver a stable cycling performance and good rate capability. −2 Even at sulfur loading of 3 mg cm , the V3S4-G sulfur cathode possesses a low capacity decay rate of 0.186% per cycle at 0.5 C. Keywords: Li-S batteries, V3S4-G, trapping sites, electrocatalytic properties
INTRODUCTION With the growing demand for energy storage devices with high energy density, lithium sulfur (Li-S) batteries have been regarded as a promising new generation battery system possessing both high specific capacity and energy density [1,2]. In addition, sulfur as the active material of cathode has abundant resources and low cost, which makes Li-S battery more competitive [3]. However, there are some issues that impede the commercialization of Li-S batteries. For instance, both of the sulfur and the reaction product Li2S are electronic and ionic insulation so that the Li-S battery has limited utilization of active materials [4–6]. Besides, the volume change of sulfur during the
cycle process leads to the pulverization of the electrode and damages the cathode structure [7,8]. Moreover, the lithium polysulfides, produced during the charge and discharge process, can dissolve in the ether-based electrolytes traveling through the separator [9]. The dissolved lithium polysulfides can react with the lithium metal anode resulting in low coulombic efficiency and fast capacity decay [10–12]. To date, there have been large amounts of studies focusing on the aspects of the electrode structure, the membrane design and the use of novel types of binders to improve the battery performance [13–17]. As for the Li-S batteries, the reasonable design of the cathode framework is the critical factor to promote the development of such high energy storage system. The carbon materials with high conductivity and high specific surface area are suitable to act as the sulfur host to encapsulate sulfur and buffer the volume change [18–23]. However, the nonpolar carbon-carbon bond has weak affinity
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