Module-Designed Carbon-Coated Separators for High-Loading, High-Sulfur-Utilization Cathodes in Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries have great potential as next-generation energy-storage devices because of their high theoretical charge-storage capacity and the low cost of the sulfur cathode. To accelerate the development of lithium–sulfur technology, it is necessary to address the intrinsic material and extrinsic technological challenges brought about by the insulating active solid-state materials and the soluble active liquid-state materials. Herein, we report a systematic investigation of module-designed carbon-coated separators, where the carbon coating layer on the polypropylene membrane decreases the irreversible loss of dissolved polysulfides and increases the reaction kinetics of the high-loading sulfur cathode. Eight different conductive carbon coatings were considered to investigate how the materials’ characteristics contribute to the lithium–sulfur cell’s cathode performance. The cell with a nonporous-carbon-coated separator delivered an optimized peak capacity of 1112 mA∙h g−1 at a cycling rate of C/10 and retained a high reversible capacity of 710 mA∙h g−1 after 200 cycles under lean-electrolyte conditions. Moreover, we demonstrate the practical high specific capacity of the cathode and its commercial potential, achieving high sulfur loading and content of 4.0 mg cm−2 and 70 wt%, respectively, and attaining high areal and gravimetric capacities of 4.45 mA∙h cm−2 and 778 mA∙h g−1, respectively.

Construction of Co@N-CNTs grown on N-MoxC nanosheets for separator modification to enhance adsorption and catalytic conversion of polysulfides in Li–S batteries

“…15–19 Various carbon materials such as graphene, carbon nanotubes (CNTs), and heteroatom-doped carbon are first applied in modified separators to reduce the charge transfer resistance and the migration of LiPSs. 20–24 Among them, CNTs exhibit unique advantages in the transfer of electrons and ions due to their 1D nanostructure with a high length-diameter ratio. 25,26 Subsequently, polar materials including metal oxides, metal sulfides, and metal carbides are also introduced, 27–32 which show superior capability in adsorbing and accelerating the reaction kinetics of LiPSs.…”

Research Progress on Multifunctional Modified Separator for Lithium–Sulfur Batteries

“…The modified separator can effectively inhibit the diffusion of lithium polysulfide and improve the coulomb efficiency. On the other hand, materials with structural design and polar materials [ 21 , 22 , 23 , 24 ] are used to modify the separator, and the diffusion of lithium polysulfide is inhibited by physical adsorption [ 25 , 26 , 27 ] and chemical adsorption ( and oxygen/nitrogen functional groups) of the microporous structure [ 28 ] and improvements in the conductivity of the cathode materials. At the same time, the electronic conduction of the contact surface with the positive electrode is realized to reduce the interface impedance of the positive electrode side, achieving the secondary utilization of lithium sulfide and improve the cycle stability and active substance utilization rate of the Li-S battery.…”

Ultrafine Co-Species Interspersed g-C3N4 Nanosheets and Graphene as an Efficient Polysulfide Barrier to Enable High Performance Li-S Batteries

“…One of the most effective strategies is to design functional conductive carbonaceous materials for capturing sulfur/polysulfides, such as tuning the pore size and/or porosity (micropore, mesopore, etc.) [ 7 , 8 , 9 ], doping various heteroatoms (N, O, S, P, etc.) [ 10 , 11 , 12 , 13 ], and tailoring the morphology (CNTs, graphene, etc.)…”