In this research, the shuttle effect and the low sulfur activation of lithium–sulfur batteries were mitigated by coating the cathode side of Celgard 2400 separators with mixtures of carbon black/chitosan or carbon black/polyvinylidene fluoride using the simple slurry technique. Carbon nanoparticles and the polar groups of the polymers were responsible for boosting the reaction kinetics of sulfur and the chemical and physical trapping of lithium polysulfides. The adsorption of sulfur species in the coated separators was confirmed by the morphologic changes observed in the AFM and SEM images and by the new elements presented in the EDX spectra after 100 charge/discharge cycles. The high intensity of the peaks in the cyclic voltammograms and the long plateaus in the discharge profiles support the improvement in the reaction kinetics. The batteries with the carbon black/chitosan- and carbon black/polyvinylidene fluoride-coated separators reached high specific discharge capacities of 833 and 698 mAhg−1, respectively, after 100 cycles at 0.5 C. This is promising for this kind of technology, and detailed results are presented in the article.

Lithium–sulfur (Li–S) batteries have attracted considerable interest as next-generation high-density energy storage devices. However, their practical applications are limited by rapid capacity fading when cycling cells with high mass loading levels. This could be largely attributed to the inferior electron/ion conduction and the severe shuttling effect of soluble polysulfide species. To address these issues, composites of sulfur/ferroelectric nanoparticles/ho ley graphene (S/FNPs/hG) cathodes were fabricated for high-mass-loading S cathodes. The solvent-free and binder-free procedure is enabled using holey graphene as a unique dry-pressable electrode for Li–S batteries. The unique structure of the holey graphene framework ensures fast electron and ion transport within the electrode and affords enough space to mitigate the electrode’s volume expansion. Moreover, ferroelectric polarization due to FNPs within S/hG composites induces an internal electric field, which effectively reduces the undesired shuttling effect. With these advantages, the S/FNPs/hG composite cathodes exhibit sustainable and ultrahigh specific capacity up to 1409 mAh/gs for the S/BTO/hG cathode. A capacity retention value of 90% was obtained for the S/BNTFN/hG battery up to cycle 18. The high mass loading of sulfur ranging from 5.72 to 7.01 mgs/cm2 allows maximum high areal capacity up to ∼10 mAh/cm2 for the S/BTO/hG battery and superior rate capability at 0.2 and 0.5 mA/cm2. These results suggest sustainable and high-yielding Li–S batteries can be obtained for potential commercial applications.

In this manuscript, we are reporting the role of ferroelectric nanoparticles (FNPs) coated separators in capacity retention at high current density (200 mA/g) on S/SWCNT composite cathodes. The ferroelectric nanoparticles of Bi0.925Gd.075Fe0.95Ni0.05O3 (BGFNO) of spontaneous polarization 2.5 µC/cm2 were coated on commercial separators (PP) as well as doped in sulfur/SWCNT composite cathodes. Our results show a discharge capacity retention of 72% by using commercial separator polypropylene (PP); however, a capacity retention improvement of more than 100% was obtained for FNPs coated separator, which has been placed on the anode side as well as on the cathode side. It is observed that the FNPs coated separator due to spontaneous polarization on the anode and cathode side acts as a repulsive charge on the separator surface to retard polysulfide migration via electrostatic repulsion and protects the surface of lithium from dendrite formation due to which it gains high capacity retention as well as stability. The coated separator controls the transport of carrier ions and side reactions; however, the FNPs doped cathode acts as an absorption center for polysulfides to enhance the electrochemical performance of the cells. The significance of this study is to design an efficient methodology, which could protect electrodes from dendrite formation via coated separator and modified cathode with the FNPs via suppressing the polysulfide formation to achieve high capacity retention and electrochemical cycle stability.

In this study, we are reporting the impact of the incorporation of ferroelectric nanoparticles (FNPs), such as BaTiO3 (BTO), BiFeO3 (BFO), Bi4NdTi3Fe0.7Ni0.3O15 (BNTFN), and Bi4NdTi3Fe0.5Co0.5O15 (BNTFC), as well as the mass loading of sulfur to fabricated solvent-free sulfur/holey graphene-carbon black/polyvinylidene fluoride (S/FNPs/CBhG/PVDF) composite electrodes to achieve high areal capacity for lithium-sulfur (Li-S) batteries. The dry-press method was adopted to fabricate composite cathodes. The hG, a conductive and lightweight scaffold derived from graphene, served as a matrix to host sulfur and FNPs for the fabrication of solvent-free composites. Raman spectra confirmed the dominant hG framework for all the composites, with strong D, G, and 2D bands. The surface morphology of the fabricated cathode system showed a homogeneous distribution of FNPs throughout the composites, confirmed by the EDAX spectra. The observed Li+ ion diffusion coefficient for the composite cathode started at 2.17 × 10−16 cm2/s (S25(CBhG)65PVDF10) and reached up to the highest value (4.15 × 10−15 cm2/s) for S25BNTFC5(CBhG)60PVDF10. The best discharge capacity values for the S25(CBhG)65PVDF10 and S25BNTFC5(CBhG)60PVDF10 composites started at 1123 mAh/gs and 1509 mAh/gs and dropped to 612 mAh/gs and 572 mAh/gs, respectively, after 100 cycles; similar behavior was exhibited by the other composites that were among the best. These are better values than those previously reported in the literature. The incorporation of ferroelectric nanoparticles in the cathodes of Li-S batteries reduced the rapid formation of polysulfides due to their internal electric fields. The areal capacity for the S25(CBhG)65PVDF10 composites was 4.84 mAh/cm2 with a mass loading of 4.31 mgs/cm2, while that for the S25BNTFC5(CBhG)60PVDF10 composites was 6.74 mAh/cm2 with a mass loading of 4.46 mgs/cm2. It was confirmed that effective FNP incorporation within the S cathode improves the cycling response and stability of cathodes, enabling the high performance of Li-S batteries.