Nano-alumina@cellulose-coated separators with the reinforcedconcrete-like structure for high-safety lithium-ion batteries

Separators play a critical role in the safety and performance of lithium-ion batteries.However,commercial polyolefin separators are limited by their poor affinity with electrolytes and low melting points.In this work,we constructed a reinforced-concrete-like structure by homogeneously dispersing nano-Al_(2)O_(3) and cellulose on the separators to improve their stability and performance.In this reinforcedconcrete-like structure,the cellulose is a reinforcing mesh,and the nano-Al_(2)O_(3) acts as concrete to support the separator.After constructing the reinforced-concrete-like structure,the separators exhibit good stability even at 200℃(thermal shrinkage of 0.3%),enhanced tensile strain(tensile stress of 133.4 MPa and tensile strains of 62%),and better electrolyte wettability(a contact angle of 6.5°).Combining these advantages,the cells with nano-Al_(2)O_(3)@cellulose-coated separators exhibit stable cycling performance and good rate performance.Therefore,the construction of the reinforced-concretelike structure is a promising technology to promote the application of lithium-ion batteries in extreme environments.

12.6μm-Thick Asymmetric Composite Electrolyte with Superior Interfacial Stability for Solid-State Lithium-Metal Batteries

Solid-state lithium metal batteries(SSLMBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage cathodes/Li anodes,and to minimize the electrolyte thickness to achieve highenergy-density of SSLMBs.Herein,we develop an ultrathin(12.6μm)asymmetric composite solid-state electrolyte with ultralight areal density(1.69 mg cm^(−2))for SSLMBs.The electrolyte combining a garnet(LLZO)layer and a metal organic framework(MOF)layer,which are fabricated on both sides of the polyethylene(PE)separator separately by tape casting.The PE separator endows the electrolyte with flexibility and excellent mechanical properties.The LLZO layer on the cathode side ensures high chemical stability at high voltage.The MOF layer on the anode side achieves a stable electric field and uniform Li flux,thus promoting uniform Li^(+)deposition.Thanks to the well-designed structure,the Li symmetric battery exhibits an ultralong cycle life(5000 h),and high-voltage SSLMBs achieve stable cycle performance.The assembled pouch cells provided a gravimetric/volume energy density of 344.0 Wh kg^(−1)/773.1 Wh L^(−1).This simple operation allows for large-scale preparation,and the design concept of ultrathin asymmetric structure also reveals the future development direction of SSLMBs.

Composite polymer electrolyte reinforced by graphitic carbon nitride nanosheets for room-temperature all-solid-state lithium batteries

By virtue of the flexibility and safety, polyethylene oxide(PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets(GCN) as advanced nanofillers into PEO based electrolytes(GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared and chronoamperometry studies indicate that GCN can facilitate Li+migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3-4.2 V at 30 ℃.

Research progress on the substrate for metal-organic framework(MOF) membrane growth for separation

During the last decade, metal-organic frameworks(MOFs) have been applied in various fields due to their unique chemical and functional advantages. One of the widespread research hotspots is MOF-based membranes for separations, specifically continuous defect-free MOF membranes, which are usually grown on porous substrates. The substrate not only serves as the MOF layer support but also has a great influence on the membrane fabrication process and the final separation performance of the resultant membrane. In this review, we mainly introduce the progress focused on the substrates for MOF membranes fabrication. The substrate modifications and seeding methods aimed at synthesizing highquality MOF membranes are also summarized systematically.

A Ruddlesden-Popper oxide as a carbon dioxide tolerant cathode for solid oxide fuel cells that operate at intermediate temperatures

Solid oxide fuel cells(SOFCs) that operate at intermediate temperatures of 600 to 800℃ have recently received increased attention due to their improved durability, more rapid startup and shutdown, better sealing and lower cost than their counterparts operate at high temperatures. Nevertheless, intermediatetemperature SOFCs(IT-SOFCs) with popular perovskite cathodes contain alkaline-earth elements, which are prone to reaction with carbon dioxide(CO_(2)), even when the CO_(2) content is comparatively low. In this work, an alkaline-earth metal-free Ruddlesden-Popper oxide, Nd_(1.8)La_(0.2)Ni_(0.74)Cu_(0.21)Ga_(0.05)O_(4+δ)(NLNCG), is developed for IT-SOFC cathodes. The cell is based on an electrolyte with 8%(mol) Y_(2)O_(3)-stabilized Zr O_(2)(8YSZ). The NLNCG cathode exhibits an excellent CO_(2) tolerance, as proven by thermogravimetry analysis,in situ X-ray diffraction, I-V-P test, and electrochemical impedance spectroscopy(EIS), and stability measurements. The anode-supported single-cell Ni O-YSZ|YSZ|NLNCG outputs a peak power density of 0.522 W·cm^(-2) at 800℃. These findings suggest that NLNCG could be a highly suitable cathode material with CO_(2) tolerance for IT-SOFCs.

Simultaneous generation of electricity, ethylene and decomposition of nitrous oxide via protonic ceramic fuel cell membrane reactor

Ethylene,one of the most widely produced building blocks in the petrochemical industry,has received intense attention.Ethylene production,using electrochemical hydrogen pump-facilitated nonoxidative dehydrogenation of ethane(NDE)to ethylene,is an emerging and promising route,promoting the transformation of the ethylene industry from energy-intensive steam cracking process to new electrochemical membrane reactor technology.In this work,the NDE reaction is incorporated into a BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)electrolyte-supported protonic ceramic fuel cell membrane reactor to co-generate electricity and ethylene,utilizing the Nb and Cu doped perovskite oxide Pr_(0.6)Sr_(0.4)Fe_(0.8)Nb_(0.1)Cu_(0.1)O_(3-δ)(PSFNCu)as anode catalytic layer.Due to the doping of Nb and Cu,PSFNCu was endowed with high reduction tolerance and rich oxygen vacancies,showing excellent NDE catalytic performance.The maximum power density of the assembled reactor reaches 200 mW cm^(-2)at 750℃,with high ethane conversion(44.9%)and ethylene selectivity(92.7%).Moreover,the nitrous oxide decomposition was first coupled in the protonic ceramic fuel cell membrane reactor to consume the permeated protons.As a result,the generation of electricity,ethylene and decomposition of nitrous oxide can be simultaneously obtained by a single reactor.Specifically,the maximum power density of the cell reaches 208 mW cm^(-2)at 750℃,with high ethane conversion(45.2%),ethylene selectivity(92.5%),and nitrous oxide conversion(19,0%).This multi-win technology is promising for not only the production of chemicals and energy but also greenhouse gas reduction.

Selective synthesis of nitrate from air using a plasma-driven gas-liquid relay reaction system

The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NO_x under plasma exposure;moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution.

Enhanced air filtration performance under high-humidity condition through electrospun membranes with optimized structure

The separation stability under high-humidity is significant in practical applications for air filters.Herein,hydrophobic polyvinyl chloride(PVC)nanofiber filters with bead-on-string structure are designed to steadily remove particle matter under high relative humidity of 90%-95%.The developed hydrophobic filters possess comparable separation performance with the hydrophilic one,but greatly enhanced stability.After the introduction of beadon-string structure,the filtration performance can be furtherly improved due to the formed large cavities and hydrophobicity.Such hydrophobic PVC filters can be promising candidates for air purification in practical applications especially in wet seasons.

Novel cobalt-free tantalum-doped perovskite Ba Fe_(1-y)Ta_yO_(3-δ)with high oxygen permeation

Cobalt-free perovskite-type oxides Ba Fe_(1-y)Ta_yO_(3-δ)(0 ≤ y ≤ 0.2)were synthesized via a simple solid state reaction.The cubic perovskite structure can be obtained when y is over 0.1.Ba Fe_(0.9)Ta_(0.1)O_(3-δ)(BFT0.1)membrane shows the highest oxygen permeation flux,which can reach 1.6 ml·min^(-1)·cm^(-2)at 950 °C under the gradient of air/He.The O_2-TPD results reveal that Ba Fe_(0.9)Ta_(0.1)O_(3-δ)material shows an excellent reversibility and phase structure stability in air.The oxygen permeation flux is limited by the bulk diffusion when the membrane thickness is over 0.8 mm,and it is limited by both the bulk diffusion and the surface exchange when the membrane thickness is below 0.5 mm.Stable oxygen permeation fluxes are obtained during 180 h operation.

Analysis on the Governing Reactions in Coal Oxidation at Temperatures up to 400°C

The present study aims to further understanding of the principal reactions that occur during coal oxidation at moderate temperatures. Mass change and heat evolution of a sample were monitored by thermo-gravimetric analysis coupled with differential thermal analysis (TGA/DTA). Gaseous and solid products were traced using online or in situ Fourier trans- form infrared spectroscopy (FTIR). Measurements were conducted by heating the samples up to 400?C, with the O2 concentration in the reaction medium set at 0, 10, 21, and 40 vol%, respectively. It was observed that the mass increase of a sample between 150?C and ~275oC was a result of the accumulation of C=O containing species in the coal structure, whereas substantial mass loss and heat evolution of a sample at ~400oC can be attributed to the significant involvement of the direct “burn-off” reaction. Enrichment of O2 inthe reaction medium leads to the acceleration in oxygen chemi- sorption, formation and decomposition of the solid oxygenated complexes, as well as the “burn-off” reaction. With the temperature increasing, the oxidation process governed by oxygen chemisorption gradually shifts to that by significant decomposition reactions, and eventually to that by the direct “burn-off” reaction. Temperature boundaries of these stages can be determined using parameters defined based on a set of TG/DTA data. Shift in the governing reactions is essentially due to the diverse requirements of reactants of the reactions and their energy barriers to be overcome. In en- gineering practice, the phenomena of self-heating and spontaneous combustion of coal correspond to chemisorption and the direct “burn-off” reaction, respectively.

Modeling of U-shaped Ba0.5Sr0.5Co0.8Fe0.2O3-δhollow-fiber membrane for oxygen permeation

A mathematic model is developed for the perovskite-type mixed ionic-electronic conducting(MIEC) membrane,which makes it possible to simulate the process of oxygen separation in the U-shaped Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_3-δhollow-fiber membrane. The model correlates the oxygen permeation flux to the measurable variables. The trends of calculated results for purge operation coincide well with the experimental data, therefore the model is considerable for flux prediction under vacuum operation. Higher oxygen separation efficiency can be achieved with vacuum operation than purge operation. Parameter study with vacuum operation reveals that oxygen permeation flux increases with higher vacuum levels, and vacuum pressure of around 1.013 × 10~3 Pa is the optimal.Also, vacuum operation on the lumen side is much more efficient to achieve higher oxygen permeation flux compared with compression mode on the shell side.

Efficient ammonia electrosynthesis from nitrate via a three-step relay mechanism

Electrocatalytically converting nitrate waste to value-added ammonia(NO3−RR)is beneficial to environmental restoration and an attractive candidate for green ammonia production[1].However,developing NO_(3)^(-)RR in an energy-saving way remains a significant challenge due to the slow kinetics inherent in multi-step electron and proton transfer,making previous investigations for NO_(3)^(-)RR generally operate at a large overpotential(<-0.2 V versus reversible hydrogen electrode(RHE))to achieve optimal efficiency and industrial current for NH3 synthesis[2].

Bifunctional separator with high thermal stability and lithium dendrite inhibition toward high safety lithium-ion batteries

Coating inorganic ceramic particles on commercial polyolefin separators has been considered as an effective strategy to improve thermostability of separator.However,the introduction of the coating layer could induce pore blockage on the surface of the polyolefin separator.Herein,a ceramic composite layer that consists of alumina nanoparticles(n-Al_(2)O_(3))and halloysite nanotubes(HNTs)is designed to modify the polyethylene(PE)separator(the modified separator is denoted as AH-PE).The HNTs with hollow nanotubular structure construct a light skeleton and provide fast ion transport channels while Al_(2)O_(3)particles function as heat-resistant fillers to inhibit the shrinkage of the separator at elevated temperatures.The total thickness of AH-PE separator is only 14μm.Consequently,the mass increment of AH-PE separator decreases from 5 g/m^(2)to 3.5 g/m^(2),and the Gurley value reduces by 23%,compared with Al_(2)O_(3)coated PE separator(A-PE).Due to the synergistic effects of Al_(2)O_(3)and HNTs,AH-PE separator exhibits highly improved thermal stability(almost no shrinkage at 170℃for 30 min),high Li^(+)transference number(up to 0.47),and long cycle life of 450 h for Li|Li cells.Moreover,the Li Fe PO_(4)/Li cells assembled with AH-PE separators demonstrate improved rate capability and safety performance.

Two-dimensional Cu-porphyrin nanosheet membranes for nanofiltration

A kind of two-dimensional(2D)metal-organic framework(MOF)material,Cu-meso-tetrakis(4-carboxyphenyl)porphine(Cu-TCPP)nanosheets with wrinkled and flat morphologies are used as building blocks to assemble membranes by vacuum filtration(VF)and electrophoretic deposition(EPD)as energy-efficient nanofiltration(NF)membranes to remove dyes from water.Since the nanosheets with wrinkled structure can provide additional water transport channels,thereby increasing the water permeance,in the premise of a high rejection(>97.0%)for the dye brilliant blue G(BBG)(1.60 nm×1.90 nm),the water permeance of the membrane assembled by the wrinkled nanosheets(~1170 nm)is about 4 times that of the membrane assembled by the flat nanosheets(~530 nm),reaching 16.39 L·m^(−2)·h^(−1)·bar^(−1).Additionally,the use of the relatively flat nanosheets and the membrane preparation method of electrophoretic deposition is more conducive to stack nanosheets orderly and reduce defects.Therefore,the water permeance of the membrane prepared by EPD(~1170 nm)with flat nanosheets is about twice that of the membrane prepared by VF(~530 nm),achieving 9.40 L·m^(−2)·h^(−1)·bar^(−1)with similar rejection(>97.0%)of dye evans blue(EB)(3.10 nm×1.20 nm).Furthermore,these membranes still exhibit good separation performance at high pressure of 0.6 MPa.Nanosheets with diverse structures and various membrane fabrication processes provide new directions for the separation performance optimization of 2D MOF materials for water purification.

High safety separators for rechargeable lithium batteries

Lithium-ion batteries(LIBs)are presently dominant mobile power sources due to their high energy density,long lifespan,and low self-discharging rates.The safety of LIBs has been concerned all the time and become the main problem restricting the development of high energy density LIBs.As a significant part of LIBs,the properties of separators have a significant effect on the capacity and performances of batteries and play an important role in the safety of LIBs.In recent years,researchers devoted themselves to the development of various multi-functional safe separators from different views of methods,materials,and practical requirements.In this review,we mainly focus on the recent progress in the development of high-safety separators with high thermal stability,good lithium dendritic resistance,high mechanical strength and novel multifunction for high-safety LIBs and have in-depth discussions regarding the separator's significant contribution to enhance the safety and performances of the batteries.Furthermore,the future directions and challenges of separators for the next-generation high-safety and high energy density rechargeable lithium batteries are also provided.

Recent progress of two-dimensional nanosheet membranes and composite membranes for separation applications

Two-dimensional(2D)materials have emerged as a class of promising materials to prepare high-performance 2D membranes for various separation applications.The precise control of the interlayer nano-channel/sub-nanochannel between nanosheets or the pore size of nanosheets within 2D membranes enables 2D membranes to achieve promising molecular sieving performance.To date,many 2D membranes with high permeability and high selectivity have been reported,exhibiting high separation performance.This review presents the development,progress,and recent breakthrough of different types of 2D membranes,including membranes based on porous and non-porous 2D nanosheets for various separations.Separation mechanism of 2D membranes and their fabrication methods are also reviewed.Last but not the least,challenges and future directions of 2D membranes for wide utilization are discussed in brief.

Predicting Illness Severity and Short-Term Outcomes of COVID-19:A Retrospective Cohort Study in China

Introduction COVID-19,caused by SARS-CoV-2,is a highly contagious disease.1 By April 8,2020,more than 1,350,000 patients were diagnosed with COVID-19 globally,with more than 79,000 deaths worldwide attributable to the disease.2 Recent clinical data reported that mild and critical patients manifested different symptoms.Most of the mild patients with COVID-19 had symptoms such as fever,cough,and mild pneumonia,whereas the critical cases presented dyspnea,respiratory failure,sepsis,organ dysfunction,and even eventual death.

Dual inhibition of glycolysis and oxidative phosphorylation by aptamer-based artificial enzyme for synergistic cancer therapy

Dual inhibition of glycolysis and oxidative phosphorylation(OXPHOS)can break the metabolic plasticity of cancer cells to inhibit most energy supply and lead to effective cancer therapy.However,the pharmacokinetic difference among drugs hinders these two inhibitions to realize a uniform temporal and spatial distribution.Herein,we report an aptamer-based artificial enzyme for simultaneous dual inhibition of glycolysis and OXPHOS,which is constructed by arginine aptamer modified carbon-dots-doped graphitic carbon nitride(AptCCN).AptCCN can circularly capture intracellular arginine attribute to the specific binding ability of arginine aptamers to arginine,and further catalyze the oxidation of enriched arginine to nitric oxide(NO)under red light irradiation.In vitro and in vivo experiments showed that arginine depletion and NO stress could inhibit glycolysis and OXPHOS,leading to energy blockage and apoptosis of cancer cells.The presented aptamer-based artificial enzyme strategy provides a new path for cell pathway regulation and synergistic cancer therapy.