Transformation of CO2 based on metal−organic framework (MOF) catalysts is becoming a hot research topic, not only because it will help to reduce greenhouse gas emission, but also because it will ...allow for the production of valuable chemicals. In addition, a large number of impressive products have been synthesized by utilizing CO2. In fact, it is the formation of new covalent bonds between CO2 and substrate molecules that successfully result in CO2 solidly inserting into the products, and only four types of new CX bonds, including CH, CC, CN, and CO bonds, are observed in this exploration. An overview of recent progress in constructing CX bonds for CO2 conversion catalyzed by various MOF catalysts is provided. The catalytic mechanism of generating different CX bonds is further discussed according to both structural features of MOFs and the interactions among CO2, substrates, as well as MOFs. The future opportunities and challenges in this field are also tentatively covered.
The transformation of CO2 into value‐added chemicals has received particular attention in recent years. The formation of covalent bonds between CO2 and substrates catalyzed by metal–organic frameworks are summarized. The catalytic mechanism of generating different CX bonds is discussed. The critical challenges and potential solutions, future opportunities and prospects in this field are also covered.
Lithium–sulfur (Li–S) batteries promise great potential as high‐energy‐density energy‐storage devices due to their ultrahigh theoretical energy density of 2600 Wh kg−1. Evaluation and analysis on ...practical Li–S pouch cells are essential for achieving actual high energy density under working conditions and affording developing directions for practical applications. This review aims to afford a comprehensive overview of high‐energy‐density Li–S pouch cells regarding 7 years of development and to point out further research directions. Key design parameters to achieve actual high energy density are addressed first, to define the research boundaries distinguished from coin‐cell‐level evaluation. Systematic analysis of the published literature and cutting‐edge performances is then conducted to demonstrate the achieved progress and the gap toward practical applications. Following that, failure analysis as well as promotion strategies at the pouch cell level are, respectively, discussed to reveal the unique working and failure mechanism that shall be accordingly addressed. Finally, perspectives toward high‐performance Li–S pouch cells are presented regarding the challenges and opportunities of this field.
High‐energy‐density lithium–sulfur pouch cells are cpomprehensively reviewed regarding the key design parameters, the current performances, and recent advances on failure analysis and promotion strategies on cathode, electrolyte, and anode.
Stable operation at elevated temperature is necessary for lithium metal anode. However, Li metal anode generally has poor performance and safety concerns at high temperature (>55 °C) owing to the ...thermal instability of the electrolyte and solid electrolyte interphase in a routine liquid electrolyte. Herein a Li metal anode working at an elevated temperature (90 °C) is demonstrated in a thermotolerant electrolyte. In a Li|LiFePO4 battery working at 90 °C, the anode undergoes 100 cycles compared with 10 cycles in a practical carbonate electrolyte. During the formation of the solid electrolyte interphase, independent and incomplete decomposition of Li salts and solvents aggravate. Some unstable intermediates emerge at 90 °C, degenerating the uniformity of Li deposition. This work not only demonstrates a working Li metal anode at 90 °C, but also provides fundamental understanding of solid electrolyte interphase and Li deposition at elevated temperature for rechargeable batteries.
A Li metal anode working at 90 °C is demonstrated in a thermotolerant liquid electrolyte. The anode undergoes 100 cycles in a Li|LiFePO4 battery at 90 °C (10 cycles in a practical carbonate electrolyte). High operation temperature promotes independent and incomplete decomposition of Li salts and solvents to form a distinctive solid electrolyte interphase.
The lifespan of high‐energy‐density lithium metal batteries (LMBs) is hindered by heterogeneous solid electrolyte interphase (SEI). The rational design of electrolytes is strongly considered to ...obtain uniform SEI in working batteries. Herein, a modification of nitrate ion (NO3−) is proposed and validated to improve the homogeneity of the SEI in practical LMBs. NO3− is connected to an ether‐based moiety to form isosorbide dinitrate (ISDN) to break the resonance structure of NO3− and improve the reducibility. The decomposition of non‐resonant −NO3 in ISDN enriches SEI with abundant LiNxOy and induces uniform lithium deposition. Lithium–sulfur batteries with ISDN additives deliver a capacity retention of 83.7 % for 100 cycles compared with rapid decay with LiNO3 after 55 cycles. Moreover, lithium–sulfur pouch cells with ISDN additives provide a specific energy of 319 Wh kg−1 and undergo 20 cycles. This work provides a realistic reference in designing additives to modify the SEI for stabilizing LMBs.
The modification of NO3− is achieved by connecting NO3− to an ether‐based moiety. The broken resonance structure of −NO3 improves its reducibility compared with NO3−. The decomposition of −NO3 forms a LiNxOy‐rich solid electrolyte interphase (SEI) and induces uniform Li deposition.
High‐energy‐density lithium (Li) metal batteries are severely hindered by the dendritic Li deposition dictated by non‐uniform solid electrolyte interphase (SEI). Despite its unique advantages in ...improving the uniformity of Li deposition, the current anion‐derived SEI is unsatisfactory under practical conditions. Herein regulating the electrolyte structure of anions by anion receptors was proposed to construct stable anion‐derived SEI. Tris(pentafluorophenyl)borane (TPFPB) anion acceptors with electron‐deficient boron atoms interact with bis(fluorosulfonyl)imide anions (FSI−) and decrease the reduction stability of FSI−. Furthermore, the type of aggregate cluster of FSI− in electrolyte changes, FSI− interacting with more Li ions in the presence of TPFPB. Therefore, the decomposition of FSI− to form Li2S is promoted, improving the stability of anion‐derived SEI. In working Li | LiNi0.5Co0.2Mn0.3O2 batteries under practical conditions, the anion‐derived SEI with TPFPB undergoes 194 cycles compared with 98 cycles of routine anion‐derived SEI. This work inspires a fresh ground to construct stable anion‐derived SEI by manipulating the electrolyte structure of anions.
Directly regulating the electrolyte structure of anions by an anion receptor was proposed for the construction of a stable anion‐derived solid electrolyte interphase (SEI). The introduction of an anion receptor decreases the reduction stability of FSI− and increases the amount of FSI− in the form of AGG‐II. The decomposition of FSI− to form Li2S is promoted, improving the stability of the anion‐derived SEI under practical conditions.
The lithium–sulfur (Li–S) battery is regarded as a promising high‐energy‐density battery system, in which the dissolution–precipitation redox reactions of the S cathode are critical. However, soluble ...Li polysulfides (LiPSs), as the indispensable intermediates, easily diffuse to the Li anode and react with the Li metal severely, thus depleting the active materials and inducing the rapid failure of the battery, especially under practical conditions. Herein, an organosulfur‐containing solid electrolyte interphase (SEI) is tailored for the stabilizaiton of the Li anode in Li–S batteries by employing 3,5‐bis(trifluoromethyl)thiophenol as an electrolyte additive. The organosulfur‐containing SEI protects the Li anode from the detrimental reactions with LiPSs and decreases its corrosion. Under practical conditions with a high‐loading S cathode (4.5 mgS cm−2), a low electrolyte/S ratio (5.0 µL mgS−1), and an ultrathin Li anode (50 µm), a Li–S battery delivers 82 cycles with an organosulfur‐containing SEI in comparison to 42 cycles with a routine SEI. This work provokes the vital insights into the role of the organic components of SEI in the protection of the Li anode in practical Li–S batteries.
An organosulfur‐containing solid electrolyte interphase (SEI) is tailored for the stabilization of the Li anode in Li–S batteries by employing 3,5‐bis(trifluoromethyl)thiophenol as an electrolyte additive. The organosulfur‐containing SEI protects the Li anode from the detrimental reactions with Li polysulfides (LiPSs). A Li–S battery delivers 82 cycles with an organosulfur‐containing SEI in comparison to 42 cycles with a routine SEI under practical conditions.
The lifespan of practical lithium (Li)‐metal batteries is severely hindered by the instability of Li‐metal anodes. Fluorinated solid electrolyte interphase (SEI) emerges as a promising strategy to ...improve the stability of Li‐metal anodes. The rational design of fluorinated molecules is pivotal to construct fluorinated SEI. Herein, design principles of fluorinated molecules are proposed. Fluoroalkyl (−CF2CF2−) is selected as an enriched F reservoir and the defluorination of the C−F bond is driven by leaving groups on β‐sites. An activated fluoroalkyl molecule (AFA), 2,2,3,3‐tetrafluorobutane‐1,4‐diol dinitrate is unprecedentedly proposed to render fast and complete defluorination and generate uniform fluorinated SEI on Li‐metal anodes. In Li–sulfur (Li−S) batteries under practical conditions, the fluorinated SEI constructed by AFA undergoes 183 cycles, which is three times the SEI formed by LiNO3. Furthermore, a Li−S pouch cell of 360 Wh kg−1 delivers 25 cycles with AFA. This work demonstrates rational molecular design principles of fluorinated molecules to construct fluorinated SEI for practical Li‐metal batteries.
Design principles of fluorinated molecules were proposed to construct a fluorinated solid electrolyte interphase for practical lithium‐metal batteries.
Display omitted
•Research progress of g-C3N4-based photocatalytic membranes has been reviewed.•We emphasize the importance of g-C3N4 structure tailoring for membrane fabrication.•g-C3N4-based ...membranes exhibit superiority for water decontamination and antifouling.•Future perspectives for g-C3N4-based photocatalytic membranes are given.
Due to the synergistically enhanced efficiency and self-cleaning performance, photocatalytic membranes provide an energy sustainable and environment friendly approach for water purification. Constructing photocatalytic membranes with visible-light responsiveness is of great scientific and technical importance for the long-term stability of support membranes and the fully utilization of solar energy. Graphite carbon nitride (g-C3N4), a visible-light driven photocatalyst with tailorable structures and excellent stability, has emerged as an attractive material for membrane applications. Herein, in order to introduce the recent advances of this field, we present a critical review on g-C3N4-based photocatalytic membranes. We firstly summarize the tailoring strategies that can be used to improve the photocatalytic activity of g-C3N4 and facilitate the membrane processing. The fabrication and modification methods of g-C3N4-based photocatalytic membranes are discussed, with an emphasis on the critical role of carbon nanomaterials, function molecules and theoretical calculations. The fundamental contribution of modified g-C3N4 to the mechanism of organic pollutant degradation and the fouling control of composite membranes is illustrated. Finally, the perspectives for the future study and the practical applications of g-C3N4-based photocatalytic membranes are proposed.
The lithium–sulfur (Li–S) battery is regarded as a promising secondary battery. However, constant parasitic reactions between the Li anode and soluble polysulfide (PS) intermediates significantly ...deteriorate the working Li anode. The rational design to inhibit the parasitic reactions is plagued by the inability to understand and regulate the electrolyte structure of PSs. Herein, the electrolyte structure of PSs with anti‐reductive solvent shells was unveiled by molecular dynamics simulations and nuclear magnetic resonance. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether (DIPE) as a cosolvent, DIPE molecules tend to distribute in the outer solvent shell due to poor solvating power. Furthermore, DIPE is more stable than conventional ether solvents against Li metal. The reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. Consequently, the cycling performance of working Li–S batteries was significantly improved and a pouch cell of 300 Wh kg−1 was demonstrated. The fundamental understanding in this work provides an unprecedented ground to understand the electrolyte structure of PSs and the rational electrolyte design in Li–S batteries.
The electrolyte structure of lithium polysulfides (PSs) with anti‐reductive solvent shells was unveiled. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether as a cosolvent, the reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. The stability of practical Li–S batteries was improved and a pouch cell of 300 Wh kg−1 was demonstrated.
