Superior Low-temperature Performance Research Articles

Highly sulfonated poly ether ether ketone chelated with Cu2+ as a proton exchange membrane at sub-zero temperatures

Improving the proton conductivity (σ) of proton exchange membranes at low temperatures is very important for expanding their application areas. Here, sulfonated poly ether ether ketone (SPEEK) membranes were prepared with different sulfonation degrees, and its maximum ion exchange capacity is 3.15 mmol/g for 10 h at 60 °C. Highly sulfonated SPEEK membrane exhibits ultra-high water uptake and excellent proton conductivity of 0.074 S/cm at −25 °C due to its abundant −SO3H. Nevertheless, its high swelling ratio and low mechanical strength are not conducive to the practical application of the membrane. Luckily, by employing the chelation of Cu2+ with −SO3− on the SPEEK chain, Cu2+-coordinated SPEEK membranes were prepared, and they not only retain high −SO3H content but also possess robust mechanical properties and good dimensional stability compared to pristine SPEEK membrane. Meanwhile, the σ of the SPEEK-Cu membrane reaches 0.054 S/cm at −25 °C, and its fuel cell maximum power (Wmax) reaches 0.42 W/cm2 at −10 °C, demonstrating superior low-temperature performance in comparison to other reported materials. Particularly, water states in the prepared membranes are quantified by low-temperature differential scanning calorimetry. Because much more water bound to the plentiful −SO3H and Cu2+ inside the membrane endows it with anti-freezing performance, the decay of the σ and the Wmax for the SPEEK-Cu membrane is retarded at sub-zero temperatures. It is envisioned that composite membranes comprising metal ions such as Cu2+-SPEEK have a high potential for sub-zero fuel cell applications.

Orthorhombic K3V3(PO4)4: A low-temperature cathode material for potassium-ion batteries

Potassium-ion battery has been considered as a promising energy storage device with low cost and high sustainability. However, its low-temperature performance is always poor due to the large size of K+ ions and poor ion transportation capability under low temperature. In this work, a carbon-coated orthorhombic K3V3(PO4)4/C cathode material for potassium-ion batteries is developed with promising low-temperature cycle performance. At −10 °C, K3V3(PO4)4/C retains a reversible capacity of 52.2 mAh/g for 1400 cycles at a current density of 100 mA g−1. The superior low-temperature performance is attributed to its open framework structure, which provides three-dimension channels for K-ion transportation. It is revealed that V3+/V4+ redox dominates the charge compensation in K3V3(PO4)4/C during charge and discharge processes. Carbon coating can not only reduce the charge transfer resistance of the electrode and prevent electrode cracking, but also helps to the formation of CF3-rich interfaces between the cathode and electrolyte, ensuring high interfacial stability of K3V3(PO4)4/C during cycling.

Nutrient and salinity stress induced biodiesel production from a green alga, Monoraphidium neglectum

The potential of a green alga as a versatile and sustainable feedstock for biodiesel production was assessed. Molecular identification revealed the alga to be Monoraphidium neglectum. Under diverse growth conditions, including nutrient deficiency and salinity stress, the microalga showed robust adaptability. Under nitrate deficiency (N-, the lipid content peaked (30.67 %), with a notable increase in monounsaturated fatty acids (MUFA), reaching 50.72 % in the stressed sample. Additionally, the highest polyunsaturated fatty acid (PUFA) content (24.55 %) was observed at a salinity level of 0.12 M. At 0.01 M salinity, the highest total carbohydrate content was observed. A significant fatty acid methyl ester (FAME) yield of 85.08 % was obtained under nitrate deficiency (N-) emphasizing its biodiesel production potential. The as-obtained biodiesel exhibited low viscosity, superior low-temperature performance and enhanced oxidation stability rendering the alga as an ideal candidate for eco-friendly, sustainable biodiesel production.

3D-printing of attapulgite monoliths with superior low-temperature selective catalytic reduction activity: the influence of thermal treatment

This study provides a facile strategy for 3D-printing of attapulgite monoliths with superior low-temperature NH3-SCR performance under thermal treatment.

The Statistical Analysis on Physical and Rheological Properties of the Bitumen Modified with CR+SBS+Sasobit

In this study, crumb rubber (CR), styrene-butadiene-styrene (SBS) and warm mix additive (Sasobit) modified bitumen binders were statistically investigated. The data set consisting of 32 binders modified by pure, CR, SBS, Sasobit and CR+SBS+Sasobit was studied. While additive ratios were defined as independent variables, results obtained from softening point, viscosity, dynamic shear rheometer and bending beam rheometer experiments were defined as dependent variables. Experiment results were analyzed individually and collectively using response surface methodology and pearson correlation methods. When the experiments were evaluated individually, very important relationships were found between additives rates and all experimental results. Actual values and estimated values obtained as a result of statistical analysis overlapped. It was determined that there were strong relationships between all experimental results when the pearson correlation between the experimental results was examined. Optimization was made according to the test results where the viscosity of 3000 cP (suitable workability), softening point and dynamic shear rheometer test results were maximum (superior high temperature performance) and the test result of bending beam rheometer was minimum (superior low temperature performance). According to this, CR, SBS and Sasobit rates were determined as 5.6%, 4% and 1%, respectively.

Crystal growth regulation of Cu-SSZ-13 zeolites for effective catalytic reduction of NOx from automotive exhausts

In this study, glucose was used in the synthesis of SSZ-13 zeolites; it acted as a zeolite growth regulator to successfully change the morphology of SSZ-13 zeolites. The particle size of the SSZ-13 zeolites reduced from 10 to 3 μm, and the morphology of the zeolite surface changed from rough and irregular spherical to smooth and uniform cubic. The glucose-modified SSZ-13 zeolites were ion-exchanged with Cu2+ ions (named as Cu-SSZ-13-Glu) and tested for the catalytic reduction of NOx with NH3 (NH3–SCR). The results demonstrated that the catalyst Cu-SSZ-13-Glu exhibited better NH3–SCR catalytic performance than that of conventional Cu-SSZ-13, with a wider effective reaction window, superior low-temperature SCR performance, favorable anti-SO2 poisoning ability, and excellent hydrothermal stability. The characterization results of the Cu-SSZ-13-Glu sample revealed an increase in crystallinity as well as acidic sites, and an improvement in the redox properties. After hydrothermal aging, compared with traditional Cu-SSZ-13, the Cu-SSZ-13-Glu zeolites exhibited a more stable structure and maintained higher crystallinity, larger specific surface area, and microporous volume. Moreover, the Cu2+ ions in the Cu-SSZ-13-Glu zeolites were more stable, and fewer CuOx species were generated after hydrothermal aging, retaining more Cu2+ ions species and acidic sites. To summarize, the simply prepared Cu-SSZ-13-Glu zeolites exhibited excellent catalytic activity and hydrothermal stability, showing broad application prospects in the field of nitrogen oxide removal from automotive exhausts.

Nonflammable Fluorinated Ester-Based Electrolytes for High Voltage Li Batteries with LiCoO2 Positive Electrode

LiCoO2 is widely used as a positive electrode material for LIBs. The theoretical capacity of LiCoO2 is calculated to be 274 mA h g–1 upon full delithiation, but the practical reversible capacity is generally restricted to approximately 140 mA h g–1 to avoid capacity deterioration when cycled at higher voltages (>4.2 V vs Li/Li+). To solve this limitation, functional electrolytes that possess a high oxidative stability and form a stable and effective passivation layer on the LiCoO2, are desired.In this study, we report that the cyclability of LiCoO2 under high-voltage operation is drastically improved by using a fluorinated ester, methyl 3,3,3-trifluoropropionate (MTFP), as an electrolyte solvent.1 Notably, the combined use of MTFP-based electrolyte and mixed sodium carboxymethyl cellulose/styrene-butadiene rubber binder synergistically stabilize the LiCoO2 electrode surface, resulting in the almost no capacity fading for 50 cycles even with the upper cutoff voltage of 4.5 V. Note that, in general, LiCoO2 shows significant capacity deterioration when cycled at higher voltages over 4.2 V vs Li/Li+. Moreover, our study reveals that superior low-temperature performance and higher thermal stability is evidenced for the LiCoO2 with MTFP-based electrolyte when compared with that with conventional electrolyte. XPS analysis reveals that thinner and uniform passivation layer derived from PF6 – anion and MTFP is formed on the LiCoO2 electrode surface, which is the origin for improved cyclability and thermal stability of high-voltage LiCoO2 with MTFP-based electrolyte.Reference[1] Y. Ugata et al., and N. Yabuuchi, Chemistry of Materials, in press.

Fabrication of iron-based amorphous reinforced CoCrNi medium-entropy alloys by selective laser melting: Enhancement of mechanical properties and improvement of corrosion resistance

Due to their exceptional mechanical characteristics and corrosion resistance, CoCrNi medium-entropy alloys have been the subject of increasing interest in recent years. In this study, CoCrNi medium entropy alloys strengthened with iron-based amorphous materials were fabricated using Selective Laser Melting (SLM) technology, with established gradients at 0, 3, 5, and 7 wt%. At room temperature, the yield strength and hardness of the CoCrNi-5MG specimen showed marked improvements of 27.5 % and 34.7 % respectively, compared to its pure CoCrNi counterpart, while still preserving a considerable fracture elongation of 24 %. Under low-temperature conditions, all samples prepared via Selective Laser Melting (SLM) demonstrated significant improvements in yield strength and fracture plasticity. Furthermore, the CoCrNi samples doped with iron-based amorphous material exhibited superior low-temperature performance, with the increase in plasticity exceeding that of the Pure CoCrNi samples compared to room temperature conditions. Importantly, an increase in the content of iron-based amorphous material resulted in a decrease in the corrosion current density, thereby noticeably enhancing corrosion resistance. Our study proposes an innovative approach to enhancing the strength and corrosion resistance of CoCrNi medium-entropy alloys. This is achieved by incorporating iron-based amorphous materials during the SLM preparation process, thereby providing a new avenue for optimizing its properties.

Reducing the poisoning effect of adsorbed alkaline earth metal on Nb active sites with sulfates for NH3-SCR

Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NOx with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO2-S) for trapping calcium species, and Nb/MnO2-S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NOx activity in a wide operating temperature window (175–350 °C, over 80 % NOx conversion with a gas hourly space velocity of 60,000 h−1) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO2-S, thus accelerating the redox cycle in NH3-SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO2, relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO2-S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications.

Toward Superior Low-Temperature Performance and Safe Cathode Slurry Fabrication via 3-Methoxy-N,N-dimethylpropionamide as a Low-Toxicity and Facile Solvent

Toward Superior Low-Temperature Performance and Safe Cathode Slurry Fabrication via 3-Methoxy-<i>N,N</i>-dimethylpropionamide as a Low-Toxicity and Facile Solvent

Study on the Tensile and Fatigue Properties of the FH36 Ship Steel Plates at Room and Low Temperatures

This study investigated the tensile properties and fatigue behavior of FH36 steel plates subjected to alternating rolling processes in different directions, as well as their performance at room temperature and −60 °C. The results revealed that by employing sequential rolling in both the rolling and transverse directions, the disparities in the mechanical properties between these two directions were eliminated, resulting in nearly identical tensile performances. The macroscopic features of the high-cycle and low-cycle fatigue fractures at both room temperature and at −60 °C were similar, with high-cycle fatigue fractures exhibiting oblique shear features and low-cycle fatigue fractures exhibiting cup-cone shapes. The crack initiation zones were consistently located on the surface of the specimens. As the maximum stress increased, the area of the high-cycle fatigue crack propagation zone decreased, while the area of the final fracture zone, the number of dimples, and the proportion of low-angle grain boundaries all increased. Under −60 °C conditions, the critical crack length for high-cycle fatigue, the maximum stress limit for the onset of high-cycle fatigue, and the fatigue limit were all higher than those at room temperature, indicating a superior low-temperature fatigue performance.

Experimental and numerical study of Cu-SSZ-13 SCR system for NOx reduction and hydrothermal aging under diesel exhaust conditions

Selective catalytic reduction (SCR) is a crucial technique for mitigating nitrogen oxides emission of internal combustion engines. Compared with vanadium-based catalysts, copper-based molecular sieve catalysts exhibit superior low-temperature catalytic performance and anti-aging properties. The catalytic characteristics of Cu-SSZ-13 catalyst in both fresh and aged states are investigated through experimental and numerical simulations. The catalytic performance of Cu-SSZ-13 catalyst with 200 g/L coating is investigated under wide inlet temperatures (180 °C–450 °C) and ANR (ammonia to nitrogen ratio) (1–1.4) conditions via an engine emission test device. Further, the apparatus is adopted to evaluate performance at various aging temperatures (600 °C, 700 °C, and 800 °C). The aging factor is introduced based on experimental results to establish and correct the kinetic model for SCR aging state. The results illuminate that the increase of ANR fails to compensate for decline of catalytic efficiency under low-temperature conditions (150 °C).The generated quantity of isocyanate acid through the side reaction of urea hydrolysis increases proportionally with ANR. And it increased supply only resulted in a marginal 1 %–3 % improvement of catalytic efficiency. As SV decreases from 60,000 h−1 to 35,000 h−1, the catalyst efficiency increases from 22 % to 45 %, resulting in an elevation of reactant concentration and its gradient on the catalyst surface. This leads to accelerated reaction rates and enhanced diffusion effects. The catalytic efficiency can be significantly enhanced at low temperatures when NO2 fraction in NOx falls within the range of 10 %–25 %. The sensitivity of SCR reactions to aging varies at low temperatures (<250 °C) due to the distinct reaction sites on catalyst for different types of SCR reactions. The NO2 SCR reactions exhibit minimal susceptibility, while the rapid SCR reactions are significantly impeded. Moreover, it has been observed that the catalyst microstructure was completely deteriorated under hydrothermal aging test at 900 °C operating condition. In general, the low-temperature catalytic performance of Cu-SSZ-13 catalyst can be further optimized by pretreating inlet gas components and optimizing the catalyst structure.

Bifunctional Localized High-Concentration Electrolyte for the Fast Kinetics of Lithium Batteries at Low Temperatures.

Traditional lithium batteries cannot work well at low temperatures due to the sluggish desolvation process, which limits their applications in low-temperature fields. Among various previously reported approaches, solvation regulation of electrolytes is of great importance to overcome this obstacle. In this work, a tetrahydrofuran (THF)-based localized high-concentration electrolyte is reported, which possesses the advantages of a unique solvation structure and improved mobility, enabling a Li/lithium manganate (LMO) battery to cycle stably at room temperature (retains 85.9% after 300 cycles) and to work at a high rate (retains 69.0% at a 10C rate). Apart from that, this electrolyte demonstrates superior low-temperature performance, delivering over 70% capacity at -70 °C and maintaining 72.5 mAh g-1 (≈77.1%) capacity for 200 cycles at a 1C rate at -40 °C. Also, even when the rate increases to 5C, the battery could still operate well at -40 °C. This work demonstrates that solvation regulation has a significant impact on the kinetics of cells at low temperatures and provides a design method for future electrolyte design.

Study on the Low-Temperature Pre-Desulfurization of Crumb Rubber-Modified Asphalt.

Waste tires can be ground as crumb rubber (CR) and incorporated into asphalt pavement for efficient resource utilization. However, due to its thermodynamic incompatibility with asphalt, CR cannot be uniformly dispersed in the asphalt mix. In order to address this issue, pretreating the CR with desulfurization is a common way to restore some of the properties of natural rubber. The main technique of desulfurization and degradation is dynamic desulfurization, requiring a high temperature that may lead to asphalt fires, aging, and the volatilization of light substances, generating toxic gases and resulting in environmental pollution. Therefore, a green and low-temperature controlled desulfurization technology is proposed in this study to exploit the maximum potential of CR desulfurization and obtain high-solubility "liquid waste rubber" (LWR) close to the ultimate regeneration level. In this work, LWR-modified asphalt (LRMA) with superior low-temperature performance and processability, stable storage, and less susceptibility to segregation was developed. Nevertheless, its rutting and deformation resistance deteriorated at high temperatures. The results showed that the proposed CR-desulfurization technology could produce LWR with 76.9% solubility at a low temperature of 160 °C, which is close to or even better than the finished products produced at the preparation temperature of TB technology, i.e., 220-280 °C.

Engineering Surface Properties of CuO/Ce0.6Zr0.4O2 Catalysts for Efficient Low-Temperature Toluene Oxidation

The development of superior low-temperature catalytic performance and inexpensive catalysts for the removal of volatile organic compounds (VOCs) is crucial for their industrial application. Herein, CuO/Ce0.6Zr0.4O2 catalysts calcinated at different temperatures (Cu/CZ-X, X represented calcination temperature) were prepared and used to eliminate toluene. It can be found that Cu/CZ-550 presented the highest low-temperature catalytic activity, with the lowest temperature (220 °C) 50% conversion of toluene, the highest normalized reaction rate (3.1 × 10−5 mol·g−1·s−1 at 180 °C) and the lowest apparent activation energy value (86.3 ± 4.7 kJ·mol−1). Systematically, the surface properties analysis results showed that the optimum redox property, abundant oxygen vacancies, and plentiful surface Ce3+ species over Cu/CZ-550 were associated with the strong interaction between Cu and support could significantly favor the adsorption and activation of toluene, thus resulting in its superior catalytic performance.

Rational Design of Fluorinated Electrolytes for Low Temperature Lithium‐Ion Batteries

AbstractNonaqueous carbonate electrolytes are commonly used in commercial lithium‐ion battery (LIB). However, the sluggish Li+ diffusivity and high interfacial charge transfer resistance at low temperature (LT) limit their wide adoption among geographical areas with high latitudes and altitudes. Herein, a rational design of new electrolytes is demonstrated, which can significantly improve the low temperature performance below −20 °C. This electrolyte is achieved by tailoring the chemical structure, i.e., altering the fluorination position and the degree of fluorination, of ethyl acetate solvent. It is found that fluorination adjacent to the carbonyl group or high degree of fluorination leads to a stronger electron‐withdrawing effect, resulting in low atomic charge on the carbonyl oxygen solvating sites, and thus low binding energies with Li+ ions at LT. The optimal electrolyte 2,2,2‐trifluoroethyl acetate (EA‐f) shows significantly improved cycle life and C‐rate of a NMC622/graphite cell when cycled at −20 °C and −40 °C, respectively. In addition to superior LT performance, the electrolyte is nonflammable and tolerant for high voltage charging all owing to its fluorine content. This work provides guidance in designing next‐generation electrolytes to address the critical challenge at subzero temperatures.

Fabrication and morphological effect of waxberry-like carbon for high-performance aqueous zinc-ion electrochemical storage

Promoting and enhancing the transport rate of multivalent electrolyte ions in the pores of electrode is central for constructing high-performance electrochemical devices. Herein, waxberry-like porous carbon with nanosheets packaged by spherical carbon particles is produced by adjusting separation of hydrophilic and hydrophobic parts of carbon source precursors. The carbon particles maintain their original morphology after KOH activation at high temperature, forming tunable pores (pore volume: 0.9386 cm3 g−1) on the surface of stacked nanosheet layers. Benefiting from the synergistic effect of structural features, an interfacial transport of aqueous zinc ions within the carbon electrodes is achieved, endowing the assembled zinc-ion hybrid supercapacitors (ZHSCs) with excellent energy storage performances, including high capacity (122.3 mAh g−1 at 0.1 A g−1), high energy density (97.78 Wh kg−1), large power density (8000 W kg−1), and cycling stability up to 10,000 cycles with capacity retention of 98%. Moreover, the ZHSCs show superior low-temperature performance and operability (78.27 mAh g−1 at −30 °C and three-time cycling stability between −20 and 20 °C without performance degradation). This work presents a new prospect on design and development of aqueous rechargeable zinc-ion energy storage devices that are available for a range of environmental conditions.

Outstanding low temperature performance of hollow carbon sphere@MnO2 anode based on pseudo-capacitive storage mechanism

Graphite anode suffers from severe performance fading at low temperature (LT) conditions mainly due to the suppressed diffusive Li+ storage mechanism in graphite anode at LT. Accordingly, the exploration of new type anodes with effective Li+ storage mechanism at LT is important. In this work, it is demonstrated that the utilization of the pseudo-capacitive storage mechanism could improve the Li+ storage kinetic at LT. In detail, a hybrid anode structure is designed via in-situ growth of MnO2 nanosheets on the surface of the hollow carbon spheres (HCS@MO). Benefiting from the structural advantage, the as-prepared HCS@MO-09 electrode displays high reversible capacity of 455 mAh g-1 at 1 A g-1 at room temperature (RT) after 200 cycles. At − 20 ℃, the HCS@MO-09 electrode still exhibits high initial capacity of 432 mAh g-1 at 0.2 A g-1 and outstanding cycling stability. The cyclic voltammetry tests reveal that the superior LT performance of HCS@MO-09 electrode stems from the pseudo-capacitive storage mechanism. This work provides new perspective for improving LT performance through developing anodes with pseudo-capacitive storage mechanism.

Temperature-dependent structure and performance evolution of “water-in-salt” electrolyte for supercapacitor

“Water-in-salt” (WIS) electrolytes exhibit enlarged electrochemical stability windows compared to conventional dilute aqueous electrolytes, which helps to achieve high-voltage aqueous electrochemical energy storage devices. However, the ultra-high concentration of WIS electrolytes raises a serious concern about their temperature availability. Herein, we demonstrate the correlation of the temperature-dependent electrochemical performance of different-concentration electrolytes with their solvation structures and intermolecular interactions as elaborated via Raman spectroscopy and molecular dynamics simulations. The 21 m (mol kg−1) WIS electrolyte is advantageous in the high-temperature range of >25 °C, whereas the 5 m WIS electrolyte shows superior low-temperature performance, remaining a stable gel state even at −30 °C ascribed to the muscular hydrogen bond network. The electrochemical performance evaluation of carbon supercapacitors assembled with different-concentration WIS electrolytes further verify our findings. This study provides guidance to choose suitable WIS electrolytes for electrochemical energy storage devices working at different temperatures.

An aqueous magnesium-ion hybrid supercapacitor operated at −50 °C

The recent advances in aqueous magnesium-ion hybrid supercapacitor (MHSC) have attracted great attention as it brings together the benefits of high energy density, high power density, and synchronously addresses cost and safety issues. However, the freeze of aqueous electrolytes discourages aqueous MHSC from operating at low-temperature conditions. Here, a low-concentration aqueous solution of 4 mol L−1 Mg(ClO4)2 is devised for its low freezing point (−67 °C) and ultra-high ionic conductivity (3.37 mS cm−1 at −50 °C). Both physical characterizations and computational simulations revealed that the Mg(ClO4)2 can effectively disrupt the original hydrogen bond network among water molecules via transmuting the electrolyte structure, thus yielding a low freezing point. Thus, the Mg(ClO4)2 electrolytes endue aqueous MHSC with a wider temperature operation range (−50 °C–25 °C) and a higher energy density of 103.9 Wh kg−1 at 3.68 kW kg−1 over commonly used magnesium salts (i.e., MgSO4 and Mg(NO3)2) electrolytes. Furthermore, a quasi-solid-state MHSC based on polyacrylamide-based hydrogel electrolyte holds superior low-temperature performance, excellent flexibility, and high safety. This work pioneers a convenient, cheap, and eco-friendly tactic to procure low-temperature aqueous magnesium-ion energy storage device.