# Thiokol with Excellent Restriction on the Shuttle Effect in Lithium-Sulfur Batteries
## 1 Introduction  
To alleviate the current energy crisis and environmental pollution, sustainable, and eco-friendly energy conversion and storage systems are urgently needed. Rechargeable lithium-ion batteries have been attracting great attention as power sources for various applications including modern electronic devices, hybrid vehicles, and various electrical power systems [1]. Among them, lithium-sulfur (Li-S) batteries are considered as the most promising candidates for the next generation of high-energy storage devices due to their high theoretical specific capacity (1675 mAh/g) and energy density (2500 Wh/kg), which is far more than those of the commercially available Li-graphite batteries [2; 3; 4; 5; 6]. Moreover, benefitting from the goodness of sulfur substance, Li-S batteries possess the merits of the natural abundance, low cost, and environmental friendliness, which enable them more competitive against their counterparts [7]. However, large-scale commercialization of Li-S batteries is still hampered by several issues. Among them, the so-called'shuttle effect' resulting from the dissolution of lithium polysulfide intermediates (Li\({}_{2}\)S\({}_{x}\), \(4\leq x\leq 8\)) into the liquid electrolyte acts as the major obstacle. Specifically, the soluble polysulfides could diffuse through the separator and directly react with the lithium negative electrode during the discharge process; this would bring in passivation and loss of the active material, which consequently gives rise to a rapidly fading capacity and low coulombic efficiency. Besides the volume change aroused by density difference between sulfur and polysulfides, the intrinsic poorelectronic and ionic conductivity of sulfur and its discharging products (Li\({}_{2}\)S and Li\({}_{2}\)S\({}_{2}\)) also hinder the electrochemical performance of Li-S battery [8; 9; 10; 11; 12]. In recent years, extensive efforts have been devoted to solving these problems. [PERSON] et al. introduced a kind of polysulfide-scission reagents to favor the formation of insoluble Li\({}_{2}\)S and/or Li\({}_{2}\)S\({}_{2}\) instead of the soluble Li\({}_{2}\)S\({}_{7}\) (\(4\leq x\leq 8\)) during the charge/discharge process. By this strategy, the shuttle effect could be effectively suppressed and an improved electrochemical performance was achieved in the Li-S batteries [13]. [PERSON] et al. applied a lightweight TiO\({}_{2}\)/graphene interlayer as a polysulfide absorbent for Li-S batteries to suppress the shuttling of polysulfides [14]. [PERSON] et al. introduced an ordered meso-microporous core-shell carbon (MMCS) as a sulfur container, which combines the advantages of both mesoporous and microporous carbon. With large pore volume and highly ordered porous structure of carbon host, the problem of volume change and low electron transfer rate could be overcome [15]. [PERSON] et al. proposed a sulfur-polymer composite consisting of polymer acid doped polypyrrole mixed ionic\(-\)electronic conductor to improve the ion and electron transport [16]. In spite of plentiful investigations, binder is heavily overlooked by most researchers. As a matter of fact, binder is one of the most important compositions in the cathode. An eligible binder should meet several requirements including enough adhesion stress to hold the electrical contact of active material with current collector, and structure maintaining ability during the charge and discharge process without hindering the transport of electron and lithium ion. To date, only a few studies have involved the binders. [PERSON] et al. proposed a binder composed of poly (ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP), which combines the local improvement to solvent system offered by PEO and the stabilizing effect of PVP on polysulfides [17]. [PERSON] adopted a cationic polyelectrolyte binder for high sulfur loading cathodes, whose function is to retain the void structure generated by the dissolution of polysulfides and thus benefit a longer cycle life for the battery [18].