Improved lithium–sulfur batteries with a conductive coating on the separator to prevent the accumulation of inactive S-related species at the cathode–separator interface

The Effect of Binders on the Performance and Degradation of the Lithium/Sulfur Battery Assembled in the Discharged State

“…PVP has amide carbonyl functional groups that can bind relatively strongly both to Li 2 S and polysulfides, thus reducing the loss of active material as a dissolved polysulfide. 13,24,27,34 It is also believed to act as a redox mediator. PANI also has a nitrogen atom that may act as a polysulfide anchor and might even interact electrochemically with polysulfides by opening amine bonds in the presence of LiNO 3 .…”

“…To summarize, the methods of overcoming the challenges of the Li/S battery include: reducing the solubility of the polysulfides by adding toluene to THF, 9 increasing the concentration of the supporting electrolyte, 15 encapsulation of the sulfur species (S or Li 2 S) in several types of cages [24][25][26] and using polysulfide barriers and modified separators. [27][28][29] Modification of the electrolyte by the addition of nitrate, as proposed by Aurbach, 30 and film formation on the anode by its reaction with (CH 3 ) 3 SiCl, 31 were found to minimize the reaction of polysulfides with the anode, thus leading to longer cycle life.…”

New Separators in Lithium/Sulfur Cells with High-Capacity Cathodes

“…48 A simpler strategy that is relatively less explored is to modify the separator: coating a conventional polyolefin separator with an adsorbent oxide layer that may act as a physical obstacle to polysulfide migration. Examples of this approach include application of materials such as: i) a porous nitrogen and phosphorus dual-doped graphene blocking layer by Gu et al, 49 ii) a microporous polymer membrane by Li et al 50 with ∼0.8 nm pores (vs. ∼17 nm pores for Celgard 2325) resulting a 500-fold increase in polysulfide blocking ability, iii) an ion-selective membrane by Huang et al 51 based on sulfonate-ended perfluoroalkyl ether groups that allow selective ion hopping of positively charged species (Li + ) but not polysulfide anions (S n 2− ), iv) a conductive coating on the separator by Cui et al 52 to prevent the accumulation of inactive S-related species at the cathode-separator interface, v) Nafion-coated polypropylene (Celgard) separators as cation-selective membranes to suppress polysulfide diffusion by Bauer et al, 53 and vi) a thin TiO 2 /graphene interlayer over the cathode as a polysulfide adsorbent reported by Xiao et al 54 All these approaches have resulted in some partial blocking of the polysulfide diffusion from the cathode half-cell to the Li anode.…”

Recent development of metal compound applications in lithium–sulphur batteries

“…11 It was firstly applied as the additive in the sulfur cathode to improve the electrochemical performances of Li-S batteries. 100,101 Later Al 2 O 3 was applied as the coating layer on both sulfur cathodes [102][103][104] and separators, 12,73,105 which has proved to be effective in enhancing the cycle stability of Li-S batteries. For instance, Shi's group coated an ultrathin Al 2 O 3 film via ALD on the graphene-sulphur (G-S) composite.…”

“…[69][70][71][72][73] A TiO 2 nanowire-embedded graphene (TiO 2 NW/G) hybrid membrane was prepared by Manthiram's group. 74 In this hybrid membrane, the graphene with high conductivity was used as the current collector, while the TiO 2 NWs were used as a polysulphides shuttling inhibitor as well as the catalyst to accelerate the polysulfide reduction and oxidation.…”