Channels Of Metal-organic Framework Research Articles

Optimizing electrochemical power generation: Harnessing synergies and surface innovation in NiTe-modified MOF nanoarchitectures

Metal-organic frameworks (MOFs) are considered potential electrocatalysts due to their high specific surface area (SSA) and the facilitation of efficient synergistic interactions. In this work, we have implemented a simple and cost-effective surface modification approach to design an efficient electrocatalyst for energy-conversion technologies, specifically water splitting. This work focuses on engineering a novel NiTe functionalized MOF structure wherein NiTe within the MOF channels is the core material, intricately intertwined with highly dispersed Ni particles enveloped by Ni MOF. This fusion of MOFs and NiTe within a designed configuration produces an efficient electrocatalyst with synergistic and surface interface effects and demonstrates bifunctional activity for water splitting. Among the prepared catalysts, one of the resulting catalysts (named Ni MOF/Ni/Ni10Te8) exhibits a low overpotential of 99 mV for the hydrogen evolution reaction (HER) and 180 mV for the oxygen evolution reaction (OER), both benchmarked against RHE @10 mA cm−2. This performance remains steady, with a stability of 99 % after 15 h of continuous operation. Furthermore, the Ni MOF/Ni/Ni10Te8 catalyst also operates in seawater electrocatalysis, requiring a low overpotential of 440 mV at 10 mA cm−2 to produce 70 mL of hydrogen and 34 mL of oxygen. Equally noteworthy are the Faradaic efficiencies achieved, with hydrogen production at 95.7 % and oxygen production at 92.9 %. Developing efficient and economically viable electrocatalysts like the Ni MOF/Ni/NiTe catalyst will advance a cleaner and more sustainable future.

A switchable zinc-based metal organic framework for the light triggered absorption and release of organic dyes

Due to its adjustable pore structure, the metal–organic frameworks (MOFs) have attracted much attention in the treatment of organic dye molecules in wastewater. However, the general tuning of the pore channels of MOFs is mainly by changing the chain length of the organic ligands and metal nodes. This approach not only limits the types of MOFs, but also limits the treatment of a large number of dye methylene blue (MB) and methyl orange (MO) dye molecules in the wastewater. Hence, we synthesized photoresponsive Zn-AzDC/TPA MOF as adsorbents to adsorb and release organic dye molecules in a photo-controlled manner. The photoresponsive Zn-AzDC/TPA was prepared using a mixed ligand strategy, in which the azobenzene carboxylic acid derivative (AzDC) served as a photoresponsive ligand and terephthalic acid (TPA) served as a non-active ligand in coordination with zinc ion. The optical and structural properties of the synthesized Zn-AzDC/TPA was characterized by UV–vis, FT-IR, PXRD, SEM, TEM, TGA, and pore analysis. Interestingly, it was found that the photoresponsive AzDC unit of Zn-AzDC/TPA demonstrated reversible trans–cis isomerization under the alternating UV and visible light, resulting in reversible changes in the pore size of the Zn-AzDC/TPA. Its photoresponse properties can trapp and release dye molecules under light-driven conditions. This result provides a new direction for the application of photoresponsive MOF and also lays a foundation for the study of diversified optically responsive materials.

Amine Functionalization of Channels of Metal-Organic Frameworks for Effective Chemical Fixation of Carbon Dioxide: A Comparative Study with Three Newly Designed Porous Networks.

Catalytic transformation of CO2 into value-added chemical products can provide an appropriate solution for the raising environmental issues. To date, various metal-organic frameworks (MOFs) with transition metal ions have been explored for CO2 capture and conversion, but alkaline earth metal-based MOFs are comparatively less studied. Metal ions like Sr(II) having relatively large radius give rise to a high coordination number resulting in higher stability of the MOFs. Moreover, the introduction of N-rich functional group in organic linker like -NH2, -CONH- and triazole into MOF backbone enhance their CO2 capture and conversion efficiency. Herein, the effect of amine group on the catalytic efficiency of MOFs for CO2 cycloaddition with epoxides under solvent free and ambient conditions are presented. The di-carboxylates, such as 5-aminoisophthalate (AmIP) and 5-bromoisophthalate (BrIP) were utilized to synthesize Sr(II) based MOFs. The Zn(II) MOF was synthesized using tetra-carboxylate containing amide spacer (OAT) and 4-amino-4H-1,2,4-triazole (AMT). All three MOFs exhibited porous networks with guest available volume ranging from 15 to 58 %. The catalytic efficiency of the MOFs towards carbon dioxide fixation reaction was explored. The catalytic performances revealed that the presence of amine group in the channels enhances the catalytic efficiency of the MOFs.

5.1µm Ion-Regulated Rigid Quasi-Solid Electrolyte Constructed by Bridging Fast Li-Ion Transfer Channels for Lithium Metal Batteries.

An ultra-thin quasi-solid electrolyte (QSE) with dendrite-inhibiting properties is a requirement for achieving high energy density quasi-solid lithium metal batteries (LMBs). Here, a 5.1µm rigid QSE layer is directly designed on the cathode, in which Kevlar (poly(p-phenylene terephthalate)) nanofibers (KANFs) with negatively charged groups bridging metal-organic framework (MOF) particles are served as a rigid skeleton, and non-flammable deep eutectic solvent is selected to be encapsulated into the MOF channels, combined with in situ polymerization to complete safe electrolyte system with high rigidness and stability. The QSE withconstructed topological network demonstrates high rigidity (5.4GPa), high ionic conductivity (0.73 mS cm-1 at room temperature), good ion-regulated properties, and improved structural stability, contributing to homogenized Li-ion flux, excellent dendrite suppression, and prolonged cyclic performance for LMB. Additionally, ion regulation influences the Li deposition behavior, exhibiting a uniform morphology on the Li-metal surface after cycling. According to density-functional theory, KANFs bridging MOFs as hosts play a vital function in the free-state and fast diffusion dynamics of Li-ions. This work provides an effective strategy for constructing ultrathin robust electrolytes with a novel ionic conduction mode.

Hierarchically porous MOF@COF structures with ultrafast gas diffusion rate for C2H6/C2H4 separation

For ethylene purification, C2H6-selective metal–organic frameworks (MOFs) show great potential to directly produce polymer-grade C2H4 from C2H6/C2H4 mixtures. Most C2H6-traping MOFs are ultra-microporous structures so as to strengthen multiple supramolecular interactions with C2H6. However, the narrowed pore channels of C2H6-traping MOFs cause large guest diffusion barriers, greatly hampering their practical applications. Herein, we present a feasible strategy by precisely constructing hierarchically porous MOF@COF core–shell structures to address this issue. Additional mesoporous diffusion channels were incorporated between MOF crystals through the construction of the COF shell, thereby enhancing the gas adsorption kinetics. Notably, designing a core–shell MOF@COF structure with an optimal coating amount of mesoporous COF shell will further improve the gas diffusion rate. Breakthrough experiments reveal that the tailored MOF@COF composites can effectively achieve C2H6/C2H4 separation and maintain its separation performance over five continuous measurement cycles. This investigation opens up a new avenue to solve the diffusion/transfer issues and provides more opportunities and potentials for MOF@COF composites in practical separation applications.

On the Diffusion of Ionic Liquids in ILs@ZIF-8 Composite Materials: A Density Functional Theory Study.

Recently, composite materials consisting of ionic liquids (ILs) and metal-organic frameworks (MOFs) have attracted a great deal of attention due to their fantastic properties. Many theoretical studies have been performed on their special structures and gas separation applications. Yet, the mechanism for the diffusion of ILs inside MOF channels still remains unclear. Here, the DFT calculations (e.g., rigid and relaxed potential energy surface, PES, scan) together with frontier orbital analysis, natural charge analysis, and energy decomposition analysis were performed to investigate the diffusion behavior of a typical IL, [C4mim][PF6], into the ZIF-8 SOD cage. The PES profiles indicate that it is quite difficult for the cation [C4min]+ to diffuse into the cage of ZIF-8 through the pristine pores because of the large imidazole steric hindrance, which results in a large energy barrier of ca. 40 kcal·mol-1 at the least. Interestingly, the PES reveals that a successful diffusion could be obtained by thermal contributions, which enlarge the pore size through swing effects at higher temperatures. For example, both [C4mim]+ and [PF6]- could easily diffuse through the channel of the ZIF-8 SOD cage when the pore size was increased to 6.9 Å. Subsequently, electronic structure analyses reveal that the main interactions between [PF6]- or [C4mim]+ and ZIF-8 are the steric repulsion interactions. Finally, the effects of the amounts of [C4mim][PF6] on the ZIF-8 structures were investigated, and the results show that two pairs of [C4mim][PF6] per SOD cage are the most stable in terms of the interaction between energies and structural changes. With these findings, we propose that the high-temperature technique could be employed during the synthesis of IL@MOF membranes, to enrich their family members and their industrial applications.

Structurally ordered core-shell MOFs in mixed matrix membrane as magnetic sieves for O2/N2 separation

Membrane separation technology has broad application prospects in O2/N2 separation, and improving the permselectivity of membranes remains a key problem to be solved. O2 and N2 have different magnetic properties and can be separated by magnetism. In addition, coupling magnetic separation with the use of a molecular sieve supported by metal-organic frameworks (MOFs) could further enhance the separation ability. In this work, a magnetic core-shell MOF (Fe3O4@ZIF-8) was prepared as a filler, and the impacts of the Fe3O4@ZIF-8 morphology, loading, channel magnetic properties and ordered arrangement on membrane O2/N2 selectivity were evaluated. To establish a magnetic-sieving O2 permeation channel, the preparation process was carried out in a magnetic field so that the fillers in the membrane were arranged orderly. Due to the synergistic impact of the structurally ordered MOF channel and magnetism, the gas transport performance of the resulting magnetic mixed matrix membranes (MMMs) was substantially improved. Therefore, the O2 permeability and O2/N2 selectivity of the 15 wt%Fe3O4@ZIF-8-8/Pebax MMMs reached 194 Barrer and 11.97, respectively. This study not only presents a novel approach for creating high-performance O2/N2 membranes but also plays a leading role in the development of magnetism-controlled multiscale (magnetic core-shell and filler-ordered) membrane structural engineering.

Two-Dimensional Sulfonate-Functionalized Metal-Organic Framework Membranes for Efficient Lithium-Ion Sieving.

Two-dimensional (2D) membranes have shown promising potential for ion-selective separation but often suffer from the trade-off between permeability and selectivity. Herein, we report an ultrathin 2D sulfonate-functionalized metal-organic framework (MOF) membrane for efficient lithium-ion sieving. The narrow pores with angstrom precision in the MOF assist hydrated ions to partially remove the hydration shell, according to different hydration energies. The abundant sulfonate groups in the MOF channels serve as hopping sites for fast lithium-ion transport, contributing to a high Li-ion permeability. Then, the difference in affinity of the Li+, Na+, K+, and Mg2+ ions to the terminal sulfonate groups further enhances the Li-ion selectivity. The reported ultrathin MOF membrane overcomes the trade-off between permeability and selectivity and opens up a new avenue for highly permselective membranes.

Optimum relative humidity enhances CO2 uptake in diamine-appended M2(dobpdc)

Diamine-appended M2(dobpdc) metal–organic frameworks (MOFs) are a promising class of CO2 adsorbents, but the impact of relative humidity (RH) on their adsorption performance has yet to be carefully studied. We evaluated the CO2 uptake of (2-ampd)2M2(dobpdc) at varying relative humidities and associated water loadings using gravimetric and breakthrough adsorption methods. A significant enhancement in uptake is observed between 20 and 40 % RH, with an optimum of 30 % RH, at which a maximum CO2 uptake of 5.7 ± 0.2 mmol/g is achieved at 0.044 atm of CO2. These uptakes – which are above 1 CO2:diamine – suggest that humidity promotes an additional sorption mechanism beyond the well-known cooperative insertion between the metal and diamine. Temperature-programmed desorption and IR spectroscopy also indicated a second adsorption site accounting for the additional uptake, hypothesized to be carbamic acid pairs on the free amine within the MOF channel. Further increasing the humidity to 50 % RH resulted in a dramatic loss of capacity due to water-filled pores at these high humidity conditions. These results reveal the potential for a mixed mechanism in (2-ampd)2M2(dobpdc) promoted by humidity and highlight an optimum humidity range that will maximize the MOF’s utilization in CO2 capture applications.

Shackling the aqueous electrolyte via metal-organic frameworks to realize high energy density zinc-ion batteries

Ocean-like free water in conventional aqueous electrolytes leads to narrow operating voltage and parasitic reactions in rechargeable aqueous Zn ion batteries (AZIBs), which is highly undesirable. Herein, a quasi-solid aqueous electrolyte (QSAE) with a typical bulk liquid electrolyte confined inside the sub-nanoscale channels of metal-organic framework (MOFs) is proposed to tackle this issue. Detailed experiments and theoretical calculations suggest that the unfavored side reactions, e.g., corrosion, hydrogen evolution reaction, and dendrite growth on zinc surface can be effectively depressed and the electrochemical window can be expanded to 2.51 V (based on OER), achieved by the proposed MOF-QSAE because of the tailored solvation structure of Zn2+ and the restrained activity of water molecules in MOF-QSAE. Thanks to the unexpected merits of MOF-QSAE, a fabricated Zn|MOF-QSAE|V2O5 full cell exhibits an ultra-high coulombic efficiency (average value≈99.98 %) and cycle stability (capacity retention: 81.89 % after 2000 cycles). The Zn|MOF-QSAE|V2O5 full cell can even work at a low temperature of −10 ℃ for 4000 cycles without obvious performance degradation. In addition, a high-voltage AZIBs based on zinc hexacyanoferrate (ZnHCF) cathode yields an average operating voltage of more than 1.70 V and a high energy density of ≈102 Wh kg−1, further validating the practicality of the MOF-QSAE. The proposed new type of QSAE could pave a new way for the commercialization of aqueous batteries.

Water-Accelerated Transport: Vapor-Phase Nerve Agent Simulant Delivery within a Catalytic Zirconium Metal-Organic Framework as a Function of Relative Humidity.

Zirconium-based metal-organic frameworks (MOFs) are candidate materials for effective nerve agent detoxification due to their thermo- and water stability as well as high density of catalytic Zr sites. However, as high-porosity materials, most of the active sites of Zr-MOFs can only be accessed by diffusion into the crystal interior. Therefore, the transport of nerve agents in nanopores is an important factor in the catalytic performance of Zr-MOFs. Here, we investigated the transport process and mechanism of a vapor-phase nerve agent simulant, dimethyl methyl phosphonate (DMMP), through a representative Zr-MOF, NU-1008, under practical conditions of varying humidity. Confocal Raman microscopy was used to monitor the transport of DMMP vapor through individual NU-1008 crystallites, where the relative humidity (RH) of the environment was tuned to understand the impact of water. Counterintuitively, water in the MOF channels, instead of blocking DMMP transport, assists DMMP diffusion; indeed, the transport diffusivity (Dt) of DMMP in NU-1008 is one order of magnitude higher at 70% than 0% RH. To understand the mechanism, magic angle spinning NMR and molecular dynamics simulations were performed and suggested that high water content in the channels prevents DMMP from hydrogen-bonding with the nodes, allowing for faster diffusion of DMMP in the channels. The simulated self-diffusivity (Ds) of DMMP is observed to be concentration-dependent. At low loading of DMMP, Ds is higher at 70% RH than 0% RH, while at high loadings the trend reverses due to the DMMP aggregation in water and the reduction of free volume in channels.

Enhanced proton conductivity and overall water splitting efficiency of dye@MOF by post-modification of MOF

Herein, dye@MOF composite was prepared by the encapsulation of 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) into the pores of metal-organic framework (MOF). Firstly, the proton conductivities (σ) of MOF and dye@MOF were evaluated, the σ value of dye@MOF is 10 times that of MOF at 100 ​°C, which indicates dye@MOF has excellent proton conduction capacity. Secondly, MOF and dye@MOF show excellent catalytic performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline medium, that is, when the current density is 10 ​mA•cm−2, the overpotentials of MOF and dye@MOF are 225 ​mV and 194 ​mV for OER, and 511 ​mV and 497 ​mV for HER, respectively. Moreover, an asymmetric electrolyzer of dye@MOF/nickel foam (NF)||dye@MOF/NF was assembled to assess the efficiency of dye@MOF for overall water splitting, the result shows that the current density of dye@MOF is 35 ​mA•cm−2 at 1.98 ​V, which exceeds that of MOF-based electrode. The excellent catalytic activity and enhanced proton conductivity of dye@MOF is mainly attributed to encapsulating dye molecules into the channels of MOF. In view of superior catalytic activity and excellent stability, dye@MOF is expected to be a bifunctional electrocatalyst for HER and OER.

Solid-State Investigation, Storage, and Separation of Pyrophoric PH3 and P2 H4 with α-Mg Formate.

Phosphane, PH3 -a highly pyrophoric and toxic gas-is frequently contaminated with H2 and P2 H4 , which makes its handling even more dangerous. The inexpensive metal-organic framework (MOF) magnesium formate, α-[Mg(O2 CH)2 ], can adsorb up to 10 wt % of PH3 . The PH3 -loaded MOF, PH3 @α-[Mg(O2 CH)2 ], is a non-pyrophoric, recoverable material that even allows brief handling in air, thereby minimizing the hazards associated with the handling and transport of phosphane. α-[Mg(O2 CH)2 ] further plays a critical role in purifying PH3 from H2 and P2 H4 : at 25 °C, H2 passes through the MOF channels without adsorption, whereas PH3 adsorbs readily and only slowly desorbs under a flow of inert gas (complete desorption time≈6 h). Diphosphane, P2 H4 , is strongly adsorbed and trapped within the MOF for at least 4 months. P2 H4 @α-[Mg(O2 CH)2 ] itself is not pyrophoric and is air- and light-stable at room temperature.

Isomer of NU-1000 with a Blocking c-pore Exhibits High Water-Vapor Uptake Capacity and Greatly Enhanced Cycle Stability.

Chemically and hydrolytically stable metal-organic frameworks (MOFs) have shown great potential for many water-adsorption-related applications. However, MOFs with large pores that show high water-uptake capacity and high hydrolytic and mechanical cycle stability are rare. Through a deliberate adjustment of the linker of a typical zirconium-based MOF (Zr-MOF) (NU-1000), a new isomer of NU-1000 with blocked c-pores, but large mesopores was successfully synthesized. This new isomer, ISO-NU-1000, exhibits excellent water stability, one of the highest water vapor uptake capacities, and excellent cycle stability, making it a promising candidate for water-vapor-sorption-based applications such as water-adsorption-driven heat transfer. We find that the high water-cycling stability of ISO-NU-1000 is traceable to its blocking c-pore that hinders the hydrolysis of node-coordinating formate in the c-pore area and thereby prevents the introduction of node aqua and terminal hydroxo ligands. With the absence of these ligands and their ability to hydrogen-bond to channel-located water molecules, the strength of guest (water)/host (MOF) interactions is diminished and the absolute magnitude of the capillary force exerted by water during its evacuation from MOF channels is attenuated. The attenuation leaves the MOF capable of resisting pore collapse, capacity loss, and crystallinity loss during repetitive evaporative removal (and re-introduction) of water from pores.

Rapid Fabrication of High-Permeability Mixed Matrix Membranes at Mild Condition for CO2 Capture.

Mixed matrix membranes (MMMs), conjugating the advantages of flexible processing-ability of polymers and high-speed mass transfer of porous fillers, are recognized as the next-generation high-performance CO2 capture membranes for solving the current global climate challenge. However, controlling the crystallization of porous metal-organic frameworks (MOFs) and thus the close stacking of MOF nanocrystals in the confined polymer matrix is still undoable, which thus cannot fully utilize the superior transport attribute of MOF channels. In this study, the "confined swelling coupled solvent-controlled crystallization" strategy is employed for well-tailoring the in-situ crystallization of MOF nanocrystals, realizing rapid (<5 min) construction of defect-free freeway channels for CO2 transportation in MMMs due to the close stacking of MOF nanocrystals. Consequently, the fabricated MMMs exhibit approximately fourfold enhancement in CO2 permeability, i.e., 2490 Barrer with a CO2 /N2 selectivity of 37, distinctive antiplasticization merit, as well as long-term running stability, which is at top-tier level, enabling the large-scale manufacture of high-performance MMMs for gas separation.

Polydopamine-guarded metal-organic frameworks as co-delivery systems for starvation-assisted chemo-photothermal therapy

Cutting off glucose provision by glucose oxidase (GOx) to famish tumors can be an assistance with chemotherapy to eliminate cancer cells. Co-encapsulation of GOx and chemotherapeutics (doxorubicin) within pH-sensitive metal-organic frameworks (MOFs) could disorder metabolic pathways of cancer cells and generate excessive intracellular reactive oxygen species (ROS), together. To prevent premature leach of GOx from the porous channels of MOFs, polydopamine (PDA) was deposited on the surface of MOFs, which endowed the delivery system with photothermal conversion ability. Our nanoscaled co-delivery system (denoted as DGZPNs) remains stable with low amount of drug leakage under simulated physiological conditions in vitro and internal environment, while they are triggered to release doxorubicin (DOX) and GOx in acid tumor microenvironment and at high temperature for reinforced chemotherapy. NIR laser irradiation also activates superior photothermal conversion efficiency of PDA (36.9 %) to initiate hyperthermia to ablate tumor tissue. After being phagocytized by 4 T1 cells (breast cancer cells), the DGZPNs delivery system showed a superior therapeutic efficacy with a tumor growth inhibition of 88.9 ± 6.6 % under NIR irradiation, which indicated that the starvation-assisted chemo-photothermal therapy prompts the significant advance of synergistic therapy in a parallelly controlled mode.

Construction of angstrom-scale ion channels with versatile pore configurations and sizes by metal-organic frameworks

Controllable fabrication of angstrom-size channels has been long desired to mimic biological ion channels for the fundamental study of ion transport. Here we report a strategy for fabricating angstrom-scale ion channels with one-dimensional (1D) to three-dimensional (3D) pore structures by the growth of metal-organic frameworks (MOFs) into nanochannels. The 1D MIL-53 channels of flexible pore sizes around 5.2 × 8.9 Å can transport cations rapidly, with one to two orders of magnitude higher conductivities and mobilities than MOF channels of hybrid pore configurations and sizes, including Al-TCPP with 1D ~8 Å channels connected by 2D ~6 Å interlayers, and 3D UiO-66 channels of ~6 Å windows and 9 − 12 Å cavities. Furthermore, the 3D MOF channels exhibit better ion sieving properties than those of 1D and 2D MOF channels. Theoretical simulations reveal that ion transport through 2D and 3D MOF channels should undergo multiple dehydration-rehydration processes, resulting in higher energy barriers than pure 1D channels. These findings offer a platform for studying ion transport properties at angstrom-scale confinement and provide guidelines for improving the efficiency of ionic separations and nanofluidics.

Metal-organic frameworks as chemical nanoreactors for the preparation of catalytically active metal compounds.

Since the emergence of metal-organic frameworks (MOFs), a myriad of thrilling properties and applications, in a wide range of fields, have been reported for these materials, which mainly arise from their porous nature and rich host-guest chemistry. However, other important features of MOFs that offer great potential rewards have been only barely explored. For instance, despite the fact that MOFs are suitable candidates to be used as chemical nanoreactors for the preparation, stabilization and characterization of unique functional species, that would be hardly accessible outside the functional constrained space offered by MOF channels, only very few examples have been reported so far. In particular, we outline in this feature recent advances in the use of highly robust and crystalline oxamato- and oxamidato-based MOFs as reactors for the in situ preparation of well-defined catalytically active single atom catalysts (SACS), subnanometer metal nanoclusters (SNMCs) and supramolecular coordination complexes (SCCs). The robustness of selected MOFs permits the post-synthetic (PS) in situ preparation of the desired catalytically active metal species, which can be characterised by single-crystal X-ray diffraction (SC-XRD) taking advantage of its high crystallinity. The strategy highlighted here permits the always challenging large-scale preparation of stable and well-defined SACs, SNMCs and SCCs, exhibiting outstanding catalytic activities.

Hetero-Polycrystalline Membranes with Narrow and Rigid Pores for Molecular Sieving.

Molecular sieving membranes have great potential for energy-saving separations, but they suffer from permeability-selectivity trade-off limitation. In this report, simultaneous hetero-crystallization and hetero-linker coordination of metal-organic framework (MOF) hollow fiber membranes through one-pot synthesis for precise gas separation is reported. It is found that the hetero-polycrystalline membranes consist of 2D and 3D MOF phases and are defect-free and roughly orientated, hetero-linker exchange of 3D phase by larger geometric ones can narrow transport pathway, and framework rigidification occurs and thus fixes MOF channels. The prepared membranes are robust and reproducible, and exhibit substantially improved performance, with H2 /CO2 , H2 /N2 , and H2 /CH4 selectivities up to 361, 482, and 541, respectively, accompanied by high H2 permeance over 1100gas permeation units, which can easily outclass trade-off upper bounds of state-of-the-art membranes.

An improved 9 micron thick separator for a 350 Wh/kg lithium metal rechargeable pouch cell

The use of separators that are thinner than conventional separators (> 20 µm) would improve the energy densities and specific energies of lithium batteries. However, thinner separators increase the risk of internal short circuits from lithium dendrites formed in both lithium-ion and lithium metal batteries. Herein, we grow metal-organic frameworks (MOFs) inside the channels of a polypropylene separator (8 µm thick) using current-driven electrosynthesis, which aggregates the electrolyte in the MOF channels. Compared to unmodified polypropylene separators, the MOF-modified separator (9 µm thick) vastly improves the cycling stability and dendrite resistance of cells assembled with Li metal anodes and carbonate-based electrolytes. As a demonstration, a 354 Wh kg−1 pouch cell with a lithium metal anode and LiNi0.8Co0.15Al0.05O2 (NCA)-based cathode (N/P = 3.96) is assembled with 9 µm layer of the MOF-modified separator and retains 80% of its capacity after 200 cycles (charged at 75 mA g−1, discharged at 100 mA g−1) at 25 °C.