# Thiokol with Excellent Restriction on the Shuttle Effect in Lithium-Sulfur Batteries
## 3 Results and Discussion
With an initial value of 813 mAh/g at 0.1 C, the capacity of Li-S batteries with the Thiokol binder remained around 720, 680, and 505 mAh/g at 0.2, 0.5, and 1 C in 20 cycles, respectively, and returned back to 739 mAh/g when the rate was 0.1 C. While for the battery with PVDF binder, the cell only reserved 52.2% of the  
Figure 2: (**a**) Cycling performance of the battery at 0.1 C with the binder of Thiokol and PVDF, respectively; (**b**) Cycling performance of the battery with the Thiokol binder at 0.5 C; (**c**) Cycling performance of the battery with the Thiokol and PVDF binder at different rate; (**d**) Electrochemical impedance spectra of the battery with the Thiokol and PVDF binder before and after cycling. capacity when the rate went back to 0.1 C after a continuous cycling of 0.1, 0.2, and 0.5 C. In contrast, the excellent reversibility of the capacity as high as 90.9% supported strongly again that the Li-S battery with Thiokol binder was highly stable and reversible. Electrochemical impedance spectra (EIS) of the battery with the Thiokol and PVDF binder before and after circles are shown in Figure 2d in the frequency range from 0.01 Hz to 100 kHz. The Nyquist plots of the battery with Thiokol binder consist of two semicircles, which correspond to the charge-transfer resistance (R\({}_{\mathrm{ct}}\)) occurring at the electrolyte-electrode interface in the medium-to-low frequency region and the resistance (R\({}_{\mathrm{t}}\)) from a passivation film in the high frequency region, respectively. While the Nyquist plots of the battery with PVDF binder only involve one semicircle that corresponds to R\({}_{\mathrm{ct}}\). The intersection between the initial part of the Nyquist plot and the real axis represents the electrolyte resistance (R\({}_{\mathrm{e}}\)). A few increase of R\({}_{\mathrm{e}}\) for the battery with Thiokol binder was observed after 50 cycles, which might reveal that most of the polysulfides still remain in the cathode. This could also reflect the restriction of Thiokol on the shuttle effect. Besides, compared to the battery before cycling, there is no obvious increase of R\({}_{\mathrm{ct}}\) for the battery with Thiokol binder, which indicates that the Thiokol binder enables the conductive contacts between active materials and acetylene black during the charge and discharge process by stabilizing the structure in 50 cycles. Moreover, the slight decrease of R\({}_{\mathrm{t}}\) for the battery with Thiokol binder demonstrates the prevention for the formation of passivation films upon cycling. Meanwhile, the increase of R\({}_{\mathrm{ct}}\) for the battery with PVDF binder can be ascribed to the dissolution of insulating polysulfides. The results above make it clear that the excellent performance of cells with the Thiokol binder could owe to the effective suppression of shuttle effect and stable structure of the cathode [25,26]. Scanning electron microscope (SEM) analysis was used for further insight into the excellent performance of the sulfur cathode with the Thiokol binder. The SEM images in Figure 3a,b show the cathode morphology before and after cycles with the Thiokol binder. It is obvious that sulfur particles with a size of around 1\(\upmu\)m disperse evenly in the composite before cycling. While after 50 cycles, no intact sulfur particle can be found since they have been taken advantage of and the reaction products distributed evenly in the cathode. Due to the formation of SEI (solid electrolyte interface) and the infiltration of electrolyte during the cycling, the particle morphology has been changed from independent to connected ones, which could lead to an improvement of the ionic migration. The Energy Dispersive X-Ray Spectroscopy (EDX) of the element carbon and sulfur (Figure 3c,d) also shows their homogeneous distribution after cycling. This indicates that the electrode structure is stable during the cycling. Figure 3: _Cont._  
Figure 4a shows the photos of the polysulfides in the electrolyte without and with different binders.