Metal–Organic Framework-Based Separators for Enhancing Li–S Battery Stability: Mechanism of Mitigating Polysulfide Diffusion

Abstract

The shuttling effect of polysulfides severely hinders the cycle performance and commercialization of Li−S batteries, and significant efforts have been devoted to searching for feasible solutions to mitigate the effect in the past two decades. Recently, metal−organic frameworks (MOFs) with rich porosity, nanometer cavity sizes, and high surface areas have been claimed to be effective in suppressing polysulfide migration. However, the formation of large-scale and grain boundary-free MOFs is still very challenging, where a large number of grain boundaries of MOF particles may also allow the diffusion of polysulfides. Hence, it is still controversial whether the pores in MOFs or the grain boundaries play the critical role. In this study, we perform a comparative study for several commonly used MOFs, and our experimental results and analysis prove that a layer of MOFs on a separator did enhance the capacity stability. Our results suggest that the chemical stability and the aggregation (packing) morphology of MOF particles play more important roles than the internal cavity size in MOFs.

The Role of Current Collector in Enabling the High Performance of Li/S Battery

“…These differences are reflected into a more compact and uniform electrode using the GDL (Figure c) with respect to that using Al which shows cracking and discontinuities (Figure d). The improved electrode characteristics observed by SEM may actually enhance the contact between sulfur and carbon particles in the slurry, thus accounting for the lower resistance and better performances in lithium cell, as observed in Figure and Figure ,. Furthermore, detailed SEM images with increasing magnification (Figure e, f) reveal the micrometric flakes of graphene containing sulfur, and super‐P carbon which is one of the slurry components, that is, the electron conducting additive of the 3DNG−S electrode coated on the support.…”

MOF Derived High Surface Area Enabled Porous Co3O4 Nanoparticles for Supercapacitors

“…The obtained BET surface area, average pore diameter and total pore volume of ZIF‐67 are 521.862 m 2 g –1 , 3.792 nm, and 0.3028 cc g −1 , respectively, and for Co 3 O 4 are 149.586 m 2 g –1 , 3.805 nm and 0.1067 cc g −1 , respectively (Table S3). The surface area of Co 3 O 4 was found to be superior over most of the reported Co 3 O 4 nanostructures (Table S4), therefore, it was expected to deliver high electrochemical performance. Such type of a porous structure with a large surface area is beneficial for continuous charging–discharging to relieve huge volume changes and it also provides suitable channels for fast as well as smooth electronic/ionic transportation …”

Metal–Organic Coordination Strategy for Obtaining Metal‐Decorated Mo‐Based Complexes: Multi‐dimensional Structural Evolution and High‐Rate Lithium‐Ion Battery Applications

“…[41,46,47] Based on the analysis, several results can be summarized:i )85.3 %o ft he total capacity is identified as the capacitive contribution from the nanopetals, whichi sm uch highert han the values of 72.2 %a nd 58.1 %f or the multilayers and microflowers,r espectively;i i) the capacitive contribution accountsf or more of the total capacity with increasing the scan rate (Figure 7b,c ). [41,46,47] Based on the analysis, several results can be summarized:i )85.3 %o ft he total capacity is identified as the capacitive contribution from the nanopetals, whichi sm uch highert han the values of 72.2 %a nd 58.1 %f or the multilayers and microflowers,r espectively;i i) the capacitive contribution accountsf or more of the total capacity with increasing the scan rate (Figure 7b,c ).…”

“…[45] The contributions of battery behavior and capacitance could then be quantitatively calculated by dividing the total current i into ad iffusion-controlled part (proportional to v 1/2 )a nd acapacitive part (proportionaltov): where k 1 and k 2 can be obtained by plotting iv À1/2 versus v 1/2 . [41,46,47] Based on the analysis, several results can be summarized:i )85.3 %o ft he total capacity is identified as the capacitive contribution from the nanopetals, whichi sm uch highert han the values of 72.2 %a nd 58.1 %f or the multilayers and microflowers,r espectively;i i) the capacitive contribution accountsf or more of the total capacity with increasing the scan rate (Figure 7b,c ). These results demonstrate the advantages of 2D architectures and heteroatom doping for obtaining high performance.…”