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Summary Polysulfide retention and catalysis are currently among the most important factors toward solving much of the technical challenges of lithium-sulfur (Li-S) batteries. Taking advantage of the electronic structure specific to tantalum, we explore the application of amorphous tantalum oxide with oxygen vacancies embedded inside a microporous carbon matrix as an electrocatalyst for the Li-S system. Through a pore-constriction mechanism, the dimensions of tantalum oxide are controlled to be nanosized with abundant polysulfide-retaining and catalytically active sites. High cycle and rate performances were achieved at practically relevant sulfur loadings and electrolyte content. We believe our identification of tantalum as a new catalyst material for Li-S batteries will incite more investigation into the specific selection of transition metals based on their electronic structures. Meanwhile, the “ship in a bottle” strategy will enlighten the structure design for energy conversion and storage systems.

Lithium anode‐based batteries (LBs) are highly demanded in society owing to the high theoretical capacity and low reduction potential of metallic lithium. They are expected to see increasing deployment in performance critical areas including electric vehicles, grid storage, space, and sea vehicle operations. Unfortunately, competitive performance cannot be achieved when LBs operating under extreme temperature conditions where the lithium‐ion chemistry fail to perform optimally. In this review, a brief overview of the challenges in developing LBs for low temperature (60 °C) operation are provided followed by electrolyte design strategies involving Li salt modification, solvation structure optimization, additive introduction, and solid‐state electrolyte utilization for LBs are introduced. Specifically, the prospects of using lithium metal batteries (LMBs), lithium sulfur (Li‐S) batteries, and lithium oxygen (Li‐O2) batteries for performance under low and high temperature applications are evaluated. These three chemistries are presented as prototypical examples of how the conventional low temperature charge transfer resistances and high temperature side reactions can be overcome. This review also points out the research direction of extreme temperature electrolyte design toward practical applications., This review introduces current progress of electrolyte design in lithium metal batteries to realize improved performance under extremely low and high temperature applications. By reviewing the scientific issues related to the current electrolyte design strategy, including Li salt modification, solvent component optimization, electrolyte additive introduction and solid‐state electrolyte utilization, this review points out the research direction toward practical applications.

For ethylene/ethane separation, fabrication of facilitated transport membranes (FTMs) with properties of high ethylene permeability, selectivity, long-term stability and economic feasibility remains a great challenge. In this study, a series of deep eutectic solvents (DESs) containing NO3- as anion were designed, synthesized and characterized for the first time. Then, novel DES-FTMs were fabricated successfully through the incorporation of the transport carrier (AgNO3) into as-synthesized DESs. The investigation of structure-performance relationships of FTMs suggested that the hydrogen bond acceptors (HBAs), hydrogen bond donors (HBDs) and their molar ratios greatly manipulated separation performance of FTM, which was also greatly affected by the carrier concentration. The right combinations of HBAs, HBDs and carrier concentration could significantly enhance the ethylene/ethane selectivity up to 125. The operating conditions of the separation process were optimized, confirming ethylene/ethane selectivity increased with the decrease of the transmembrane pressure and operating temperature. The synergetic regulation of hydrogen bond and coordination interactions between DES and carrier could tune the interactions between the silver cation and its counter anion, which efficiently promoted the disassociation of carrier and increased carrier activity, leading to high ethylene permeability and ethylene/ethane selectivity. The Bronsted acidic property of HBAs endowed the FTMs with good stability. The low cost and facile availability of the DESs and carrier rendered FTMs with good economic feasibility. This study may reveal the definite potentiality of DES-FTMs in ethylene/ethane separation.

All-solid-state lithium ion batteries (ASSLBs) are considered next-generation devices for energy storage due to their advantages in safety and potentially high energy density. As the key component in ASSLBs, solid-state electrolytes (SSEs) with non-flammability and good adaptability to lithium metal anodes have attracted extensive attention in recent years. Among the current SSEs, composite solid-state electrolytes (CSSEs) with multiple phases have greater flexibility to customize and combine the advantages of single-phase electrolytes, which have been widely investigated recently and regarded as promising candidates for commercial ASSLBs. Based on existing investigations, herein, we present a comprehensive overview of the recent developments in CSSEs. Initially, we introduce the historical development from solid-state ionic conductors to CSSEs, and then summarize the fundamentals including mechanisms of lithium ion transport, key evaluation parameters, design principles, and key materials. Four main types of advanced structures for CSSEs are classified and highlighted according to the recent progress. Moreover, advanced characterization and computational simulation techniques including machine learning are reviewed for the first time, and the main challenges and perspectives of CSSEs are also provided for their future development.

Cellular membranes provide ideal archetypes for molecule or ion separations with sub-angstrom scale precision, which are featured with both extremely high permeability and selectivity due to the well-defined membrane protein channels. However, the development of bioinspired membranes with artificial channels for sub-angstrom scale ethylene/ethane (0.416 nm / 0.443 nm) separation remains an uncharted territory and a significant challenge. Herein, a bioinspired nano-ordered liquid membrane is constructed by a facile ion/molecule self-assembly strategy for highly efficient ethylene/ethane separation, which mimics the structure of cellular membrane elegantly and possesses plenty of three-dimensional (3D) nanochannels. The elaborate regulation of non-covalent interactions by optimizing the ion/molecule compositions within membrane confers the nano-ordered liquid structure with interpenetrating and bi-continuous apolar domains and polar domains, which results in the formation of regular carrier wires and enormous 3D interconnected ethylene transport nanochannels. By virtue of these 3D nanochannels, the bioinspired nano-ordered liquid membrane manifests simultaneously super-high selectivity, excellent permeance and long-term stability, which exceeds previously reported ethylene/ethane separation membranes. This methodology in this work for construction of bioinspired membrane with tunable 3D nanochannels through ion/molecule self-assembly will enlighten the design and development of high-performance separation membranes for angstrom/sub-angstrom scale ion or molecule separations.

Efficient olefin/paraffin separation is a grand challenge because of their similar molecular sizes and physical properties, and is also a priority in the modern chemical industry. Membrane separation technology has been demonstrated as a promising technology owing to its low energy consumption, mild operation conditions, tunability of membrane materials, as well as the integration of physical and chemical mechanisms. In this work, inspired by the physical mechanism of mass transport in channel proteins and the chemical mechanism of mass transport in carrier proteins, recent progress in channel‐based and carrier‐based membranes toward olefin/paraffin separations is summarized. Further, channel‐based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel‐based and carrier‐based membranes are elaborated. Future perspectives toward membrane‐based olefin/paraffin separation are proposed., Recent progress in channel‐based and carrier‐based membranes toward olefin/paraffin separations is summarized. Further, channel‐based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel‐based and carrier‐based membranes are elaborated. Future perspectives toward membrane‐based olefin/paraffin separation are proposed.

Water electrolysis represents a promising technology for the production of hydrogen fuels. High-performance and stable non-noble electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are urgently desired to improve the efficiency of water splitting for large-scale hydrogen production. Herein, a flowerlike heterojunction catalyst composed of N-doped carbon films and Mo2C nanoparticles strongly coupled with ultrasmall Ni or FeNi alloy (Ni-Mo2C/CF or FeNi-Mo2C/CF) is in-situ synthesized for efficient water splitting. The as-prepared samples with unique architecture and composition combine the synergistic effects of both geometric design and electronic modification, possessing plenty of active sites, robust heterostructures, abundant channels for rapid mass transport and electron/ion transfer, and the improved conductivity for high-efficiency charge exchange during electrocatalytic process. The optimized Ni-Mo2C/CF for HER and FeNi-Mo2C/CF for OER achieve overpotentials of 81 and 228 mV to reach 10 mA cm−2, respectively, in 1.0 M KOH. Furthermore, the FeNi-Mo2C/CF(+)//Ni-Mo2C/CF(−) alkaline water electrolyzer demonstrates a low cell voltage of 1.53 V at 10 mA cm−2, outperforming most ever-reported water electrolyzer cells, and impressive stability over 24 h at 50 mA cm−2. This work provides a facile and effective method to construct high-performance and non-precious metal electrocatalysts for commercial water splitting.

Herein, high performance polyethersulfone (PES) membranes were fabricated by introducing a series of imidazole-based deep eutectic solvents (DESs) as functional additives, which could tailor membrane structure due to the synergetic effect between DES components in phase inversion process. The addition of those DESs to the casting solutions all improved membrane porous structure, which contributed to a remarkably enhanced permeability and a high selectivity of the resultant membranes. Especially, the PES membrane with tetrabutylammonium chloride/imidazole as additive had a maximum water flux of 781 L/(m2 h), which was about 6.45 times that of the additive-free membrane, and a high BSA rejection of 97.7% at 2 bar. Moreover, the antifouling performance as well as thermal and mechanical properties of the prepared membranes was investigated. Overall, this work indicates the promise of imidazole-based DESs as alternative pore-forming additives for the fabrication of ultrafiltration membranes with superior performance.

Facilitated transport membranes (FTMs) for olefin/paraffin separations have failed to achieve commercial success due to the instability of carriers although great efforts have been made. In this work, ultra-stable and cost-efficient protic ionic liquid based FTMs (PIL-FTMs) were firstly prepared by utilizing the Bronsted acidic property of PILs to stabilize the carrier. The gas solubility in the carrier/PILs was measured and the separation performances of PIL-FTMs were evaluated systemically. The results indicated that the structure of PILs affected the C2H4 permeability and the presence of ether group and hydroxyl group in PILs significantly enhanced the C2H4/C2H6 selectivity. The carrier concentration led to structural variation of PIL-FTMs, thus manipulating the gas separation performances of PIL-FTMs. The increase of transmembrane pressure decreased C2H4 permeability and C2H4/C2H6 selectivity, indicating a typical feature of FTMs. The increase of temperature increased the C2H4 permeability but decreased C2H4/C2H6 selectivity. The separation performances of PIL-FTMs were much higher than other results in the literature. Furthermore, the PIL-FTMs exhibited excellent stability during the long-term experiments carried out for six months. Finally, the investigation of separation mechanism revealed that the hydrogen-bonding and coordinative interactions between PILs and carrier accounted for the high separation efficiency of PIL-FTMs. In all, the excellent long-term stability, outstanding separation performances and economic feasibility of PIL-FTMs could play an important role in moving these membranes toward industrial application.

Ethylene/ethane separation is one of the key industrial gas separations which challenges the world because of their similar physical properties. Membrane separation technology holds great promise to replace or combine the currently energy-intensive cryogenic distillation to achieve effective ethylene purification. In this study, a series of double-salt ionic liquid derived facilitated transport membranes (DSIL-FTMs) were designed for the first time aiming at the highly effective ethylene/ethane separation, which were configured by incorporating ethylene transport carrier and double-salt ionic liquids (DSILs) into a robust Nylon support. DSILs are the liquid ionic compositions composing of more than one cation or anion, which offer an opportunity to enhance the design flexibility and structural regulation of the corresponding FTMs. The DSIL-FTMs exhibit good ethylene/ethane separation performance as well as high thermal stability and long-term durability, where the ethylene permeability is about 250 Barrer and ethylene/ethane selectivity reaches up to 67. The spectroscopic characterizations and structure-performance relationship investigation reveal that the excellent separation performances are attributed to the favorable rearrangement of cations and anions in the DSIL-FTMs, where the newly formed ion arrangement and cation-anion interactions of DSIL-FTMs favor the building of the compact membrane structure and obtainment of high carrier activity. This study opens a novel avenue to manipulate the physical-chemical properties of separation membrane by structural diversity of DSILs, and promotes the sustainable prosperity of FTMs for energy-intensive gas molecule separations.

Deep eutectic solvents (DESs), as a new generation of designer solvents, were firstly employed to fabricate the supported liquid membranes (SLMs) for the olefin/paraffin separation via facilitated transport. The novel CuCl/DESs-SLMs were prepared by impregnating the mixture of choline chloride-glycerol based DESs and copper (I) chloride (CuCl) into the microporous nylon membranes. The results of FTIR, 1 HNMR and mass spectrometry (MS) confirmed the existence of various Cu (I)-containing anionic species and hydrogen-bond networks in the membrane liquid of CuCl/DESs. The CuCl/DESs-SLMs were characterized by scanning electron microscope (SEM), contact angle measurement and weight analysis, and their performances of CuCl/DESs-SLMs were evaluated by the C 2 H 4 /C 2 H 6 separation experiments. The effects of DESs composition, CuCl concentration, operation pressure and temperature were investigated systemically. It was found that the activity and chemical stability of Cu (I)-containing anionic species were enhanced through the hydrogen-bond interactions between the anionic species and DESs, which significantly increased the permeability of C 2 H 4 and selectivity of C 2 H 4 /C 2 H 6 . Compared with other studies, the CuCl/DESs-SLMs exhibited comparable permeability and higher selectivity up to 20 for C 2 H 4 /C 2 H 6 . In conclusion, the CuCl/DESs-SLMs provided a promising method for the C 2 H 4 /C 2 H 6 separation.

Membrane technology is a forward-looking approach for gas separation, while the implementation of membrane with high performance for ethylene/ethane separation still challenges the world. Herein, a multifunctional ternary deep eutectic solvent (DES)-based membrane was constructed for the cost-effective ethylene/ethane separation. The incorporation of a sweetener (Al(NO3)3) with the AgNO3/methylacetamide (NMA) mixture to form a ternary DES not only significantly promoted the ethylene/ethane selectivity but also enhanced the long-term stability of resultant membranes, which killed two birds with one stone. Various spectroscopic characterization and quantum mechanical calculations revealed that the complexing interaction between Ag+ and NMA and the complexing interaction between Al3+ and NO3− weakened the electrostatic interaction between Ag+ and NO3−, and improved the interaction energy between ethylene molecule and Ag+ carrier. By the synergy effects of two different complexing interactions, the ternary DES-based membranes exhibited high ethylene permeability, ethylene/ethane selectivity and stability, outperforming majority of the previously published data. Therefore, the membranes proved the grand potential for ethylene/ethane separation, and this work will shed light on the design of multifunctional liquid membranes for precise molecular separation.