Subzero Temperatures Research Articles

Facilitation of metastable ice Ⅰ - ice III phase transition of liquid foods at high-pressure sub-zero temperature by perturbation

In this study, the distribution of ice Ⅰ - ice III phase transition positions and its influencing factors on various fruit juices and food model solutions under high pressure (HP) were investigated. In addition, the effect of perturbation on induction of phase change in metastable apple juice was also explored. The phase transition positions of fruit juice samples deviated far from the theoretical value (210 MPa/ –21 °C), with pressure in range of 268 ∼ 305 MPa and temperature between –31.09 °C and –37.21 °C, with the most extreme phase transition position of 305 MPa/ –37.21 °C for apple juice. The phase change position was affected by the type of solution but not by the concentration of solutions. The cooling media namely, sodium chloride (5%, 20%) and glucose solution (5%, 20%) were used as perturbation sources to stimulate the metastable apple juice by using instantaneous volume reduction during the ice Ⅰ - ice III phase transition. They successfully promoted the phase transition of apple juice, where 20% sodium chloride solution significantly (p < 0.05) reduced the phase change pressure of apple juice to 239 MPa. The perturbation effect was influenced by the type and concentration of the perturbation source, the composition of the cavity area and the softness of the sample container.

Investigation of LiFePO4/MWCNT cathode-based half-cell lithium-ion batteries in subzero temperature environments

Investigation of LiFePO4/MWCNT cathode-based half-cell lithium-ion batteries in subzero temperature environments

Monitoring of freezing patterns within 3D collagen-hydroxyapatite scaffolds using infrared thermography

The importance of cryopreservation in tissue engineering is unceasingly increasing. Preparation, cryopreservation, and storage of tissue-engineered constructs (TECs) at an on-site location offer a convenient way for their clinical application and commercialization. Partial freezing initiated at high sub-zero temperatures using ice-nucleating agents (INAs) has recently been applied in organ cryopreservation. It is anticipated that this freezing technique may be efficient for the preservation of both scaffold mechanical properties and cell viability of TECs. Infrared thermography is an instrumental method to monitor INAs-mediated freezing of various biological entities.In this paper, porous collagen-hydroxyapatite (collagen-HAP) scaffolds were fabricated and characterized as model TECs, whereas infrared thermography was proposed as a method for monitoring the crystallization-related events on their partial freezing down to −25 °C. Intra- and interscaffold latent heat transmission were descriptively evaluated. Nucleation, freezing points as well as the degree of supercooling and duration of crystallization were calculated based on inspection of respective thermographic curves. Special consideration was given to the cryoprotective agent (CPA) composition (Snomax®, crude leaf homogenate (CLH) from Hippophae rhamnoides, dimethyl sulfoxide (Me2SO) and recombinant type-III antifreeze protein (AFP)) and freezing conditions (‘in air’ or ‘in bulk CPA’).For CPAs without ice nucleation activity, thermographic measurements demonstrated that the supercooling was significantly milder in the case of scaffolds present in a CPA solution compared to that without them. This parameter (ΔT, °C) altered with the following tendency: 10 Me2SO (2.90 ± 0.54 (‘scaffold in a bulk CPA’) vs. 7.71 ± 0.43 (‘bulk CPA’, P < 0.0001)) and recombinant type-III AFP, 0.5 mg/ml (2.65 ± 0.59 (‘scaffold in a bulk CPA’) vs. 7.68 ± 0.34 (‘bulk CPA’, P < 0.0001)).At the same time, in CPA solutions with ice nucleation activity the least degree of supercooling and the longest crystallization duration (Δt, min) for scaffolds frozen ‘in air’ were documented for CLH from Hippophae rhamnoides (1.57 ± 0.37 °C and 21.86 ± 2.93 min) compared to Snomax, 5 μg/ml (2.14 ± 0.33 °C and 19.91 ± 4.72 min), respectively).Moreover, when frozen ‘in air’ in CLH from Hippophae rhamnoides, collagen-HAP scaffolds were shown to have the longest ice-liquid equilibrium phase during crystallization and the lowest degree of supercooling followed by alginate core-shell capsules and nanofibrous electrospun fiber mats made of poly ɛ-caprolactone (PCL) and polylactic acid (PLA) (PCL/PLA) blend.The paper offers evidence that infrared thermography provides insightful information for monitoring partial freezing events in TECs when using different freezing containers, CPAs and conditions. This may further TEC-specific cryopreservation with enhanced batch homogeneity and optimization of CPA compositions of natural origin active at warm sub-zero temperatures.

Engineering of hydrogel electrolyte for aqueous Zn||LiFePO4 battery on subzero-temperature adaptability, long cycles and mechanical safety

Aqueous Zn||LiFePO4 (Zn||LFP) hybrid batteries are gaining increasing interest because of their stable charging/discharging, non-flammability, low cost, and environmental friendliness. However, aqueous hybrid batteries still face the challenges of sluggish charge transfer and ion diffusion processes due to electrolyte freezing at subzero temperatures. Herein, we designed an antifreeze hydrogel electrolyte for low-temperature Zn||LFP battery. This hydrogel electrolyte is comprised of double-network κ-carrageenan/PAAm containing moderately concentrated electrolyte (1 M ZnCl2 and 7 M LiCl), possesses high elasticity with a fracture strain of 834% and high ionic conductivity of 14.8 mS cm−1 at −40 °C. It also enables a stable Zn plating/stripping efficiency with reduced interface resistance and alleviates undesired H2 evolution. The corresponding flexible Zn||LFP battery with hydrogel electrolyte displays outstanding cycle stability with capacity retentions of 95.2% and 80.5% after 2000 cycles at −20 °C and −40 °C, respectively. In addition, the battery exhibits low self-discharge rate and retains good electrochemical stability under different destructive mechanical testing including bending, folding, and puncturing. Owing to the ion-orientation effect, cooperative solvation effect, and interface wettability, the hydrogel electrolyte endows Zn||LFP battery with prolonged cyclability, subzero-temperature operation, and mechanical safety as compared to the liquid electrolyte counterpart.

Ocean acidification increases susceptibility to sub-zero air temperatures in ecosystem engineers and limit poleward range shifts.

Ongoing climate change has caused rapidly increasing temperatures, and an unprecedented decline in seawater pH, known as ocean acidification. Increasing temperatures are redistributing species towards higher and cooler latitudes which are most affected by ocean acidification. Whilst the persistence of intertidal species in cold environments is related to their capacity to resist sub-zero air temperatures, studies have never considered the interacting impacts of ocean acidification and freeze stress on species survival and distribution. Here, a full-factorial experiment was used to study whether ocean acidification increases mortality in subtidal Mytilus trossulus and subtidal M. galloprovincialis, and intertidal M. trossulus following sub-zero air temperature exposure. We examined physiological processes behind variation in freeze tolerance using 1H NMR metabolomics, analyses of fatty acids, and amino acid composition. We show that low pH conditions (pH = 7.5) significantly decrease freeze tolerance in both intertidal and subtidal populations of Mytilus spp. Under current day pH conditions (pH = 7.9), intertidal M. trossulus was more freeze tolerant than subtidal M. trossulus and subtidal M. galloprovincialis. Conversely, under low pH conditions, subtidal M. trossulus was more freeze tolerant than the other mussel categories. Differences in the concentration of various metabolites (cryoprotectants), or in the composition of amino acids and cell membrane phospholipid fatty acids could not explain the decrease in survival. These results suggest that ocean acidification can offset the poleward range expansions facilitated by warming, and that reduced freeze tolerance could result in a range contraction if temperatures become lethal at the equatorward edge.

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.

Engineering Peculiar Cathode Electrolyte Interphase toward Sustainable and High‐Rate Li–S Batteries

AbstractThe lithium–sulfur battery is considered to be one of the most promising rechargeable energy storage systems because of its high theoretical energy density. Unfortunately, the shuttle effect during cycling causes serious loss of sulfur species and corrosion of the lithium metal anode, resulting in severe capacity decay. This work proposes to completely suppress the shuttle effect of lithium polysulfides (LiPSs) without sacrificing the interfacial Li+ transport, through in situ construction of a compact cathode electrolyte interphase (CEI), which is formed of the reaction between vinylene carbonate (VC), bis(trifluoromethane)sulfonimide ions and LiPSs in a self‐limiting manner during the initial discharge process. Hence, the CEI‐confined sulfur cathode in the VC‐based electrolyte with a solid phase conversion mechanism delivers a long‐term cycling stability and high‐rate performance, as well as excellent performance under an extreme climate in a subzero temperature of −20 °C, limited lithium source with a low N/P ratio of 1.1, and even at mechanical mutilation. The present study reveals an appealing approach to tailor the composition and interfacial structure of sulfur cathodes by in situ construction of a robust, self‐healing, and high Li+ conductive CEI from the aspect of electrolyte, and thus completely solve the issue of the shuttle effect.

Electron transfer dynamics in Schottky junction photocatalyst during electron donor-assisted hydrogen production

Electron donors (EDs) are widely used to improve the H2 production performance of Schottky junction photocatalysts, but the functions of EDs are still unknown from the perspective of electron transfer dynamics. Herein, Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction. Pt nanoclusters with a diameter of ∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature. The CdS/Pt photocatalyst using lactic acid shows a higher H2 production rate of 4762 μmol g–1 h–1 compared to that using methanol, triethanolamine, and glycerol. To understand the cause, the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H2 production are revealed by femtosecond transient absorption spectroscopy. Among the four organic EDs, lactic acid enables the fastest electron transfer rate of 1.8 × 109 s–1 and the highest electron transfer efficiency of 76% at the CdS/Pt interface due to the most efficient hole consumption. This work sheds light on the importance of efficient interfacial electron transfer for improving the photocatalytic performance of Schottky junction photocatalysts.

Stretchable conductive hydrogel with super resistance-strain stability and ultrahigh durability enabled by specificity crosslinking strategy for high-performance flexible electronics

Stretchable ionic conductive hydrogels (SICHs) are regarded as one of the indispensable components for flexible electronics desirable to provide stable signal transmission and functional reproducibility. However, the state-of-the-art SICHs demonstrate a narrow resistance-stability range and poor cyclical fatigue reliability due to ion migration limitations and the absence of the molecular design regime. Herein, we present a novel synthetic strategy that utilizes the dynamic Zn-carboxyl physical bonding, adjacent to B-hydroxyl chemical bonding, to realize the “specificity” cross-linking in pectin polymeric networks. This approach significantly extends the resistance-stability range of SICHs, while also providing remarkable longevity. Via “specificity” crosslinking design, the Zn-carboxyl physical bonding, bearing thermodynamically stable and dynamic exchange character, can break the resistance-strain dependence of ionic conductive hydrogel, offering an unprecedented resistance-stability under largely applied strain (300%). Moreover, the B-hydroxyl chemical bonding effectively overcomes the conductivity and mechanical strength trade-off dilemma due to its strong but dynamic feature, realizing the high durability of SICHs. In addition, the extraordinary tolerate harsh environment capacity was achieved by introducing glycerin to form rich hydrogen bonds in the SICHs network, which is crucial for the avoidance of congelation at subzero temperatures and dehydration resulting from the circuit heat. As a stretchable conductive component of deformable electronic devices, the SICH demonstrates extraordinary long life and stable operation. These observations reveal fresh stretchable conductive materials.

High proton conductivity of the phosphate-linked graphene oxide monolith over a wide range from subzero to moderate temperature

Achieving proton-conducting solids with high proton conductivity at subzero temperatures remains a serious challenge. Thus, it is indispensable to develop the composites with high conductivity ranging from subzero to medium temperatures (243–343 ​K). Graphene oxide (GO) as an alternative matrix can provide the rich oxygen-containing groups. Thus, we prepared a series of proton conductors by covalently linking phosphate units onto the amino-functionalized GO monoliths (denoted NGOM-P), the structures of which are determined by FT-IR, XPS, XRD and Raman characterization techniques. Further, the fast proton transfer in effective acid-base networks in NGOM-P make the monolith achieve high proton conductivity from 2.61 ​× ​10−2 ​S ​cm−1 (243 ​K) to 0.68 ​S ​cm−1 (343 ​K) under 98% relative humidity (RH).

Thermodynamic analysis of a waste heat utilization based efficient liquefaction and low-temperature adsorption carbon capture hybrid system

Cryogenic CO2 capture can obtain high-pressure and pure CO2, but existing methods are inefficient as they usually discharge the waste heat of refrigeration. Therefore, a new hybrid system is proposed to recycle the waste cooling, heat, and uncondensable CO2 of liquefaction CO2 capture into low-temperature adsorption CO2 capture. This enhances the overall energy efficiency and the CO2 recovery rate over existing cryogenic CO2 capture without external input. Moreover, it enables practical sub-zero temperature CO2 adsorption while lowering the desorption temperature to 70 °C. This system is analyzed by coupling the liquefaction CO2 capture and low-temperature adsorption CO2 capture thermodynamic models, whose heat and cooling needs are compared to that available by a vapor compression cycle. Results show that for 10% mol. CO2 flue gas, the proposed system is optimal at −53 °C and 5 MPa to yield a 2nd law efficiency of 9%, a CO2 recovery rate of 80%, and specific energy consumption of under 1.65 MJ/(kg of CO2). As the cooling demand is typically twice the heat needed for sorbent regeneration, a vapor compression cycle designed to meet the former can naturally meet the latter. Ultimately, the new hybrid system represents a new carbon capture technology with better potential to achieve carbon neutrality via waste heat utilization.

Thermally driven carbon nanotube@polycaprolactone coaxial artificial muscle fibers working in subzero environments

ABSTRACT Artificial muscle fibers driven electrothermally with excellent properties of response, stroke, and work capacity are expected to serve in some intelligent structures and systems. However, muscle fibers that operate in subzero environments are highly needed in industrial production and aerospace applications but remain challenging. Herein, we reported a coaxial artificial muscle fiber by electrospinning a sheath of polycaprolactone (PCL) nanofibers on the surface of a carbon nanotube (CNT) fiber core, achieving the actuation in response to thermal at subzero temperatures. The CNT@PCL coaxial muscle fiber under 0.3 MPa achieved a maximum contractile stroke of ~18% as the temperature changed from −130°C to 45°C. The actuation mechanism at subzero temperatures of this muscle fiber was analyzed in combination with the temperature-deformation schematic curve of different polymers. Furthermore, a temperature sensor based on this muscle fiber was developed, due to the excellent linear relationship between the contraction and temperature. A 3D-printed prosthetic arm was designed to further exhibit the application demonstrations of this muscle fiber in subzero environments. This work provides new insights into artificial muscle fibers for serving in extreme environments with ultralow temperatures.

Efficient and stable subzero operation of a PEM fuel cell with a composite anode using hydrogen-methanol composition during freeze/thaw cycles

The present research deals with the adaptation of hydrogen-air fuel cells with proton exchange membrane (PEMFC) to autonomous periodic operation at subzero ambient temperatures. The main goal of the research is to limit the influence of subzero temperatures on component integrity and electrochemical performance stability of PEMFC in the cause of the freeze-thaw (F/T) cycling test. The MEAs stability in cycling from subzero (−35 °C) to operating temperature (+35 °C) was ensured without any specific preparatory operations modeling the PEMFC stop and “cold start” procedure. This is provided through the use of hydrogen-methanol compositions (no more than 4 vol % of methanol vapor) as fuel and a composite anode. Advanced membrane-electrode assembly (MEA) based on the composite anode layer (Pt 40 /C + Pt 20 /10 wt%–SnO 2 /C) for efficient and stable subzero operation during F/T cycling. High stability of electrochemical performance of the MEA with the composite anode at subzero ambient temperatures is shown. Advantages of use a two-component fuel PEMFC for autonomous periodic operation at subzero ambient temperatures are highlighted. • The hydrogen-methanol composition is applied as a fuel for cold start procedure. • Efficiency of two-component anode in methanol vapor oxidation has been proven. • Stability of fuel cell electrochemical performance at subzero temperatures is ensured.

Modified Silicon Anode for Improved Low-Temperature Performance of Lithium-Ion Batteries

Abstract The shift away from fossil fuels for modern-day energy requirements has resulted in a higher demand for electric vehicles and has led to a critical role for lithium-ion batteries. Next-generation higher capacity electrode materials are needed to meet the demands of future electric vehicles. Lithium-ion batteries function optimally around room temperature (23 °C), but discharge capacity diminishes rapidly below 0 °C and significantly affects the population living in colder climates. Higher capacity electrode materials such as silicon need to be paired with new electrolytes that favor ideal low-temperature performance. This work pairs a typical nickel-rich lithium cathode with a modified silicon anode and a ternary carbonate/ester electrolyte to demonstrate improved discharge capacity at subzero temperature.

Effects of Hydrophobicity Treatment of Gas Diffusion Layers on Ice Crystallization in Polymer Electrolyte Fuel Cells.

The unassisted cold-start capability of polymer electrolyte fuel cells (PEFCs) remains challenging for large-scale automotive applications. Various studies have shown that the freezing of produced water at the cathode catalyst layer (CL) and gas diffusion layer (GDL) interface blocks the oxidant gas and leads to a cold-start failure. However, the impact of GDL properties, including substrate, size, and hydrophobicity, on the freezing behavior of supercooled water is yet to be thoroughly investigated. We use differential scanning calorimetry to perform non-isothermal calorimetric measurements on untreated and waterproofed GDLs (Toray TGP-H-060, Freudenberg H23). By conducting a large number of experiments (>100) for each type of GDL, we obtained the corresponding distribution of onset freezing temperature (Tonset) and found noticeable sample-to-sample variations in both untreated and waterproofed GDLs. Furthermore, ice crystallization is affected by GDL wettability, coating load, coating distribution, and GDL size, whereas the impact of the GDL substrate and saturation level is not apparent. The Tonset distribution allows for predicting the capability of PEFC freeze-start and the freezing probability of residual water at a given subzero temperature. Our work paves the way for GDL modifications toward the improved cold-start capability of PEFC by identifying and avoiding the features that systematically trigger the freezing of supercooled water with high probability.

INFLUENCE OF PRE-CURING PERIOD AT SUB-ZERO TEMPERATURE （-20℃） ON THE COMPRESSIVE STRENGTH OF CONCRETE

Average temperatures over most of Mongolia are below freezing from November through March. The lowest temperatures in January are as low as -36℃ to -40℃. However, in the extremely cold climate of Mongolia, it is often executed the concrete works even outside temperature is below -20℃. Therefore, in this experimental work, we investigated the required time span of pre-curing in order to achieve the potential strength at 28 days before being exposed to extremely low temperature（-20℃）, simulating Mongolian weather conditions. Moreover, internal temperature changes and microstructure analyses have been executed. We have found that concrete freezing temperature decreases remarkably from 0℃ to -15.6℃ with increasing pre-curing time, however, depending on the water-cement （W/C） ratio. Our experiments have shown that there was no freezable water after 14 days when the W/C ratio is below 0.39. Our research concluded that concrete should at least be cured at 20℃ for 14 days before being exposed to sub-zero temperatures, in order to reach in fair to middling potential strength at 28 days.

An investigation on the wear and subsurface deformation mechanism of CoCrFeMnNi high entropy alloy at subzero temperature

Developing high entropy alloys (HEAs) has opened up a new dimension of alloy design towards better properties than those of the existing ones. Recently, a single face-centered cubic HEA, CoCrFeMnNi, has received considerable attention due to its high strength, exceptional ductility, high hardness and outstanding fracture toughness at subzero temperatures. However, the wear and subsurface deformation mechanisms of this material under subzero temperatures have not been well understood. This work aims to explore the wear mechanisms and subsurface deformation behavior of CoCrFeMnNi at subzero temperatures down to −50 °C, with the aid of contact sliding on a tribometer using tungsten carbide balls of 6.5 mm in diameter. It was found that the HEA demonstrated abrasion wear behaviors with a lower wear rate at the room temperature. Many shear bands emerged in the neighborhood of the worn surface, indicating severe plastic deformation. It was also found that that at a subzero temperature, contact sliding would cause microstructural evolution and mechanical property variation in the subsurface.

Highly Selective Reduction of CO2 to Methane Induced by Subzero Depression of the Electrode Surface Temperature

In the CO2 reduction reaction, achieving single product selectivity with comprehensive understanding of the corresponding reaction mechanism is considered a holy grail. Among numerous reactor and electrode surface parameters, temperature has surprisingly seldom been considered as a variable for selectivity regulation due to the limited range of control in aqueous electrolytes. Here we employed a reactor design for electrode surface cooling to subzero temperatures with minimal impact on the bulk electrolyte temperature. Distinct reactivity patterns were observed when the electrode was surface-cooled, compared to those of experiments when the entire reactor was chilled. Much improved methane single product selectivity was achieved (80%, comparable to the best efficiencies reported thus far) at subzero-cooled electrodes. Moreover, significantly lower overpotentials (ca. 300 mV at identical current density) were maintained with surface cooling because the temperature of the electrolyte bath was not affected. In situ IR spectroscopy revealed that the electrode surface-adsorbed CO species was the chemical intermediate in the methane-producing pathway.

Intrinsic Anti-Freezing and Unique Phosphorescence of Glassy Hydrogels with Ultrahigh Stiffness and Toughness at Low Temperatures.

Most hydrogels become frozen at subzero temperatures, leading to degraded properties and limited applications. Cryoprotectants are massively employed to improve anti-freezing property of hydrogels; however, there are accompanied disadvantages, such as varied networks, reduced mechanical properties, and the risk of cryoprotectant leakage in aqueous conditions. Reported here is the glassy hydrogel having intrinsic anti-freezing capacity and excellent optical and mechanical properties at ultra-low temperatures. Supramolecular hydrogel of poly(acrylamide-co-methacrylic acid) with moderate water content (≈50 wt.%) and dense hydrogen-bond associations is in a glassy state at room temperature. Since hydrogen bonds become strengthened as the temperature decreases, this gel becomes stronger and stiffer, yet still ductile, with Young's modulus of 900MPa, tensile strength of 30MPa, and breaking strain of 35% at -45°C. This gel retains high transparency even in liquid nitrogen. It also exhibits unique phosphorescence due to presence of carbonyl clusters, which is further enhanced at subzero temperatures. Further investigations elucidate that the intrinsic anti-freezing property is related to a fact that most water molecules are tightly bound and confined in the glassy matrix and become non-freezable. This correlation, as validated in several systems, provides a roadmap to develop intrinsic anti-freezing hydrogels for widespread applications at extreme conditions.

Hydrogen-bonds reconstructing electrolyte enabling low-temperature aluminum-air batteries

Aqueous aluminum-air batteries are promising candidates for the next generation of energy storage/conversion systems with high safety and low cost. However, the inevitable hydrogen evolution reaction on the metal aluminum anode and the freeze of aqueous electrolytes hinder the practical application of aluminum-air batteries at both room temperatures and subzero temperatures. Herein, we report a hydrogen-bonds reconstructing electrolyte strategy to boost aluminum-air batteries through the dipole of glycerol molecule, thus suppressing the self-corrosion of aluminum anode and lowering down the freezing point of electrolyte. This glycerol-based electrolyte endows a flow aluminum-air full battery with an outstanding specific capacity of 1886 mAh g−1 and a low operating temperature of −60 °C. This finding provides a synthetic design strategy to mitigate metal corrosion and expand the application range of temperature adaptation of aqueous batteries.