High Lithium Ion Conductivity LiF/GO Solid Electrolyte Interphase Inhibiting the Shuttle of Lithium Polysulfides in Long‐Life Li–S Batteries

Abstract

The “shuttle effect” that stems from the dissolution of polysulfides is the most fatal issue affecting the cycle life of lithium‐sulfur (Li–S) batteries. In order to suppress the “shuttle effect,” a new strategy of using a highly lithium ion conductive lithium fluoride/graphene oxide (LiF/GO) solid electrolyte interphase (SEI) to mechanically prevent the lithium dendrite breakthrough is reported. When utilized in Li–S batteries, the LiF/GO SEI coated separator demonstrates significant feature in mitigating the polysulfide shuttling as observed by in situ UV–vis spectroscopy. Moreover, the restrained “shuttle effect” can also be confirmed by analysis of electrochemical impedance spectroscopy and characterization of lithium dendrites, which indicates that no insulating layer of solid Li2S2/Li2S is found on lithium anode surface. Furthermore, the LiF/GO SEI layer puts out good lithium ion conductivity as its lithium ion diffusion coefficient reaches a high value of 1.5 × 10−7 cm2 s−1. These features enable a remarkable cyclic property of 0.043% of capacity decay per cycle during 400 cycles.

Addressing the Prominent Li+ Intercalation Process of Metal Sulfide Catalyst in Li‐S Batteries

“…Similarly, Li 2 S 6 solution with Li 0.66 VS 2 showed almost the same transparent color as that of VS 2 , which indicates that there is a strong trapping capacity of Li 0.66 VS 2 with Li 2 S 6 . [26,37,38] This phenomenon is further verified by the UV-vis spectrum. As can be seen from the Figure 2c, the absorption peak of Li 2 S 6 in the visible range disappears after adding VS 2 and Li 0.66 VS 2 , indicating that the concentration of Li 2 S 6 solution decreased significantly after the interaction with VS 2 and Li 0.66 VS 2 , which is in sharp contrast to the situation of blank solution.…”

PVDF-HFP/LiF Composite Interfacial Film to Enhance the Stability of Li-Metal Anodes

“…The SEM image of asprepared LiF-coated Li exhibited some cracks (Figure 3a), whereas the CIF-coated Li surface remained dense, uniform, and intact, even after a bending treatment (Figure 3b). This results proved that although LiF worked well during the electrochemical measurement, 23,57 it was fragile, not to mention the harsher winding and scratching during battery processing. A further study of the mechanical strength to accommodate the battery technology is an interesting topic that will be conducted in the future.…”

Enhanced Polysulfide Regulation via Porous Catalytic V2O3/V8C7 Heterostructures Derived from Metal–Organic Frameworks toward High-Performance Li–S Batteries

“…Electrochemical impedance spectroscopy (EIS) spectra of the cathodes were further compared before and after 200 cycles at 0.2 C. Before cycling, the Nyquist plots (Figure e) and corresponding equivalent circuits (Figure S11) suggest that all three cathodes have charge-transfer resistance (R2, the depressed semicircle at high frequency), whereas only the S–V 2 O 3 @C@G cathode has another small interface contact resistance of the electrode bulk (R3, the depressed semicircle at middle frequency) owing to the poor conductivity of V 2 O 3 . After 200 cycles, the second semicircle in the S–V 2 O 3 @C@G cathode becomes more obvious (Figure f), which is mainly ascribed to the undesirable interface contact resistance originating from the uncontrolled deposition of insulating Li 2 S or Li 2 S 2 on the lithium anode during cycling . In contrast, S–V 2 O 3 /V 8 C 7 @C@G and S–V 8 C 7 @C@G retain one semicircle, indicating that Li 2 S or Li 2 S 2 deposits less on the lithium anode.…”