MIL‐96‐Al for Li–S Batteries: Shape or Size?

Abstract

based on connecting central metal atoms/ clusters and organic ligands, have attracted considerable attention. [3][4][5] MOFs can be rationally designed by modifying their constituting metal atoms/clusters and organic ligands, allowing a control of their shapes and sizes. [6] Shapes are typically controlled by introducing modulators (cosolvents or surfactants) that preferentially adsorb onto specific crystal planes, consequently hampering their growth. Furthermore, the size can be adjusted by changing the solvent ratio or reaction time. For these reasons, MOFs are endowed with outstanding properties and potential applications, such as in sensors, [7] electrocatalysis, [8,9] and energy-storage devices. [10,11] The porous structure of MOFs makes them promising host materials to anchor sulfur in Li-S batteries, and this has attracted considerable attention because of their high theoretical capacity (1675 mAh g −1 ). [12,13] The main obstacle to impede commercialization of Li-S batteries is the shuttle effect, leading to an irreversible loss of sulfur during the discharge process. [14] At present, a variety of carbonaceous materials have been adopted as host materials to enable uniform dispersion of sulfur. [15] However, the physical confinement of lithium polysulfides (LPS, chemical formula: Li 2 S x , 4 ≤ x ≤ 8) in nonpolar carbonaceous materials is not sufficient to prevent Metal-organic frameworks (MOFs) with controllable shapes and sizes show a great potential in Li-S batteries. However, neither the relationship between shape and specific capacity nor the influence of MOF particle size on cyclic stability have been fully established yet. Herein, MIL-96-Al with various shapes, forming hexagonal platelet crystals (HPC), hexagonal bipyramidal crystals (HBC), and hexagonal prismatic bipyramidal crystals (HPBC) are successfully prepared via cosolvent methods. Density functional theory (DFT) calculations demonstrate that the HBC shape with highly exposed (101) planes can effectively adsorb lithium polysulfides (LPS) during the charge/discharge process. By changing the relative proportion of the cosolvents, HBC samples with different particle sizes are prepared. When these MIL-96-Al crystals are used as sulfur host materials, it is found that those with a smaller size of the HBC shape deliver higher initial capacity. These investigations establish that different crystal planes have different adsorption abilities for LPS, and that the MOF particle size should be considered for a suitable sulfur host. More broadly, this work provides a strategy for designing sulfur hosts in Li-S batteries.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202107836.

Polyaniline inside the pores of high surface area mesoporous silicon as composite electrode material for supercapacitors

“… 16 Recently Huan Pang et al work suggests that MOFs (metal–organic frameworks) and its various derivatives such as multimetallic MOFs ( i.e. bimetallic and trimetallic MOFs) 17 and MIL-96-Al 18 with controllable shapes and sizes also possess enhanced charge storage (sulfur storage).…”

Challenges, interface engineering, and processing strategies toward practical sulfide‐based all‐solid‐state lithium batteries

“…54 In addition, in the inorganicpolymer composite electrolytes or nanocrystalline materials, the local accumulation or depletion of charge carriers regarding defect chemistry can cause fast diffusion pathways at the interfacial regions, deviating from the transport in the respective bulk phases. 79,202 Besides, the defects, such as pores and cracks within sulfide SEs or near the Li/SE interfaces formed during SE preparation or cell operation, are also considered to affect the penetration of lithium dendrites through SEs significantly. Lithium deposition can easily penetrate corresponding pores and cracks due to the uneven and…”

“…In certain materials, control over the concentration and atomistic nature of grain boundaries can lead to tunning of ionic conductivity due to forming pathways of undercoordinated sites to aid conduction parallel to their surface; thereby, significantly increasing observable ionic conductivities of SEs 54 . In addition, in the inorganic‐polymer composite electrolytes or nanocrystalline materials, the local accumulation or depletion of charge carriers regarding defect chemistry can cause fast diffusion pathways at the interfacial regions, deviating from the transport in the respective bulk phases 79,202 …”

Silver-Nanoparticle-Assisted Modulation of NH3 Desorption on MIL-101

“…The intrinsic properties and functions of MOFs are improved by modulation of the structural features such as the crystal size and shape as well as composition with heterogeneous components such as metal nanoparticles and polymers. 14 − 19 For example, the incorporation of silver nanowires with zeolitic imidazolate frameworks allowed an enhancement for electrochemical oxygen evolution by improving electrical conductivity. 15 Such hybrid MOFs with heterogeneous components have shown higher performance than a single MOF entity through synergistic effects, while there are few attempts to utilize the hybrid MOF for ammonia capture and storage to the best of our knowledge.…”