Polysulfide-Scission Reagents for the Suppression of the Shuttle Effect in Lithium–Sulfur Batteries

Abstract

Lithium-sulfur batteries have become an appealing candidate for next-generation energy-storage technologies because of their low cost and high energy density. However, one of their major practical problems is the high solubility of long-chain lithium polysulfides and their infamous shuttle effect, which causes low Coulombic efficiency and sulfur loss. Here, we introduced a concept involving the dithiothreitol (DTT) assisted scission of polysulfides into lithium-sulfur system. Our designed porous carbon nanotube/S cathode coupling with a lightweight graphene/DTT interlayer (PCNTs-S@Gra/DTT) exhibited ultrahigh cycle-ability even at 5 C over 1100 cycles, with a capacity degradation rate of 0.036% per cycle. Additionally, the PCNTs-S@Gra/DTT electrode with a 3.51 mg cm sulfur mass loading delivered a high initial areal capacity of 5.29 mAh cm (1509 mAh g) at current density of 0.58 mA cm, and the reversible areal capacity of the cell was maintained at 3.45 mAh cm (984 mAh g) over 200 cycles at a higher current density of 1.17 mA cm. Employing this molecule scission principle offers a promising avenue to achieve high-performance lithium-sulfur batteries.

Chemical Immobilization Effect on Lithium Polysulfides for Lithium–Sulfur Batteries

“…b) Galvanostatic charge–discharge profiles of the PCNTs–S@Gra/DTT, PCNTs–S@Gra, and PCNTs–S cathodes at 0.2 C. c) Schematic of electrode configuration for LSBs with Gra/DTT interlayer. Reproduced with permission . Copyright 2017, the Royal Society of Chemistry.…”

“…Due to the high solubility of polysulfides, Huang and co‐workers present a new method in which dithiothreitol (DTT) is used to clip polysulfides . The designed LSBs are composed of a porous CNTs/S cathode (PCNTs‐S) and a lightweight graphene/dithiothreitol (Gra/DTT) interlayer, in which the DTT can reduce the dissolution of polysulfide into electrolyte by slicing the SS bonds with improved electrochemical kinetics (Figure b).…”

3D CNTs/Graphene‐S‐Al3Ni2 Cathodes for High‐Sulfur‐Loading and Long‐Life Lithium–Sulfur Batteries

“…The anodic scan produced a large oxidation peak at 2.41 V, attributed to the conversion of Li 2 S 2 and Li 2 S to elemental S 2, 20, 29, 33, 34, 35. The negative shift in the oxidation peaks between the first and second cycles is ascribed to the rearrangement of active S from its original positions to more energetically stable sites 29, 34. Compared with the CV curves of the CNTs‐S and CNTs/Gra‐S cathodes (Figure S7, Supporting Information), the almost overlapping CV curves for the CNTs/Gra‐S‐Al 3 Ni 2 cathode in the subsequent three cycles suggest that the latter possessed excellent reversible electrochemical stability.…”

Advances in Cathode Materials for High-Performance Lithium-Sulfur Batteries

“…As a result, carbons, polymers, and metal oxides are required as additives to improve the electrochemical performance of LSBs. Second, the dissolution of intermediate polysulfides generated during cycling results in the notorious shuttling effect, leading to loss of the active material, poor cycling performance, rapid capacity attenuation, and corrosion of lithium metal (Zhang et al., 2012, Hua et al., 2017, Pan et al., 2017). Third, a large volumetric expansion of 80% occurs during the conversion from S to Li 2 S 2 /Li 2 S, leading to structural instability of the electrode and rapid decrease of battery capacity.…”