A Keggin Al13 -Montmorillonite Modified Separator Retards the Polysulfide Shuttling and Accelerates Li-Ion Transfer in Li-S Batteries.

The commercialization of Li-S batteries as a promising energy system is terribly impeded by the issues of the shuttle effect and Li dendrite. Keggin Al13 -pillared montmorillonite (AlMMT), used as the modified film of the separator together with super-P and poly (vinylidene fluoride) (PVDF), has a good chemical affinity to lithium polysulfide (LiPS) to retard the polysulfide shuttling, excellent electrolyte wettability, and a stable structure, which can improve the rate capability and cycling stability of Li-S batteries. Density function theory (DFT) calculations reveal the strong adsorption ability of AlMMT for LiPS. Consequently, the modified film allows Li-S batteries to reach 902 mAh g-1 at 0.2C after 200 cycles and 625 mAh g-1 at 1C after 1000 cycles. More importantly, a high reversible areal capacity of 4.04 mAh cm-2 can be realized under a high sulfur loading of 6.10 mg cm-2 . Combining the merits of rich resources of montmorillonite, prominent performance, simple operation and cost-effectiveness together, this work exploits a new route for viable Li-S batteries for applications.

Re-Dispersion of Platinum From CNTs Substrate to α-MoC1 - x to Boost the Hydrogen Evolution Reaction.

Developing high-performance electrocatalysts toward hydrogen evolution reaction (HER) is important for clean and sustainable hydrogen energy, yet still challenging. Herein, an α-MoC1 - x induced redispersing strategy to construct a superior HER electrocatalyst (Pt/CNTs-N + α-MoC1 - x ) by mechanical mixing of α-MoC1 - x with Pt/CNTs-N followed by thermal reduction is reported. It is found that thermo-activation treatment enables partial Pt atoms to redisperse on α-MoC1 - x substrate from carbon nanotubes, which creates dual active interfaces of Pt species dispersed over carbon nanotubes and α-MoC1 - x . Benefiting from the strong electronic interaction between the Pt atom and α-MoC1 - x , the utilization efficiency of the Pt atom and the zero-valence state of Pt is evidently enhanced. Consequently, Pt/CNTs-N + α-MoC1 - x catalyst exhibits excellent HER activity with low overpotentials of 17 and 34 mV to achieve a current density of 10 mA cm-2 in acidic and alkaline electrolytes, respectively. Density functional theory calculations further reveal that the synergistic effect between Pt and α-MoC1 - x makes it accessible for the dissociation of water molecules and subsequent desorption of hydrogen atoms. This work reveals the crucial roles of α-MoC1 - x additives, providing practical solutions to enhance platinum dispersion, and thereby enhance the catalytic activity in HER.