Explore the vast range of titles available.

In high-elevation or high-latitude permafrost areas, persistent subzero temperatures significantly impact the freeze–thaw durability of concrete structures. Traditional methods for studying the frost resistance of concrete in permafrost regions do not provide a complete picture for predicting properties, and new approaches are needed using, for example, machine learning algorithms. This study utilizes four machine learning models—Support Vector Machine (SVM), extreme learning machine (ELM), long short-term memory (LSTM), and radial basis function neural network (RBFNN)—to predict freeze–thaw damage factors in concrete under low and subzero temperature conservation conditions. Building on the prediction results, the optimal model is refined to develop a new machine learning model: the Sparrow Search Algorithm-optimized Extreme Learning Machine (SSA-ELM). Furthermore, the SHapley Additive exPlanations (SHAP) value analysis method is employed to interpret this model, clarifying the relationship between factors affecting the freezing resistance of concrete and freeze–thaw damage factors. In conclusion, the empirical formula for concrete freeze–thaw damage is compared and validated against the prediction results from the SSA-ELM model. The study results indicate that the SSA-ELM model offers the most accurate predictions for concrete freeze–thaw resistance compared to the SVM, ELM, LSTM, and RBFNN models. SHAP value analysis quantitatively confirms that the number of freeze–thaw cycles is the most significant input parameter affecting the freeze–thaw damage coefficient of concrete. Comparative analysis shows that the accuracy of the SSA-ELMDE prediction set is improved by 15.46%, 9.19%, 21.79%, and 11.76%, respectively, compared with the prediction results of SVM, ELM, LSTM, and RBF. This parameter positively influences the prediction results for the freeze–thaw damage coefficient. Curing humidity has the least influence on the freeze–thaw damage factor of concrete. Comparing the prediction results with empirical formulas shows that the machine learning model provides more accurate predictions. This introduces a new approach for predicting the extent of freeze–thaw damage to concrete under low and subzero temperature conservation conditions.

Thermal environment in vertical mine shafts has a significant influence on the shaft support and reinforcement, and on the safety of the while hoisting facility. Fluctuation of air flow temperature causes thermal deformation of structural elements in the shafts. Subzero temperature air enters mine shafts in the winter season because of deficient heating of air supply shafts and as a result of air flow reversal in ventilation shafts. As a consequence, tubing support in the shafts experiences cooling, the tubing joints open, and water inflow in the shaft goes over and above a guideline value, which can initiate an accident. The authors analyze the impact of subzero temperatures on the opening of tubing joints after change in the stress–strain behavior of the tubing ring–concrete lining–rock mass system. The developed and implemented numerical model of the mentioned geotechnical system determines patterns of temperatures and deformations in tubing rings in the periods of exposure to cold.

Lithium-ion batteries have high energy density, excellent life cycle, and low self-discharge characteristics, but their performance is sensitive to temperature. In particular, the performance of lithium-ion batteries is degraded, and the internal resistance increased may prevent the battery from operating such as charged or discharged at subzero temperatures. Therefore, the study of thermal stability of lithium-ion batteries at low temperatures is as important as the battery thermal safety problem at high temperatures. In this paper, an analysis of preheating methods for battery packs designed for aircraft engine startup in low-temperature environments is conducted. The battery pack was designed by the design constraints that assumed ambient of −32 °C. The preheating is carried out using external heating for operation of the battery pack in low-temperature environments. Sixteen resistance heaters are installed inside the battery pack, which consists of 112 cylindrical lithium-ion cells. In addition, for effective heating of cylindrical battery cells, the battery cells are inserted inside the aluminum square battery tray, and the resistance heaters are attached sides of the battery tray for heating it. The thermal analysis when the designed preheating method was applied was carried out to review thermal distributions such as temperature uniformity of batteries according to heating. The heating volume of the resistance heater and the modification of the aluminum tray was considered, and the modified design method provided additional cell temperature homogeneity within the battery pack, resulting in thermal management strategy to use the battery pack in low temperatures.

Bio-inspired self-healing materials hold great promise for applications in wearable electronics, artificial muscles and soft robots, etc. However, self-healing at subzero temperatures remains a great challenge because the reconstruction of interactions will experience resistance of the frozen segments. Here, we present an ultrarobust subzero healable glassy polymer by incorporating polyphenol nano-assemblies with a large number of end groups into polymerizable deep eutectic solvent elastomers. The combination of multiple dynamic bonds and rapid secondary relaxations with low activation energy barrier provides a promising method to overcome the limited self-healing ability of glassy polymers, which can rarely be achieved by conventional dynamic cross-linking. The resulted material exhibits remarkably improved adhesion force at low temperature (promotes 30 times), excellent mechanical properties (30.6 MPa) and desired subzero healing efficiencies (85.7% at −20 °C). We further demonstrated that the material also possesses reliable cryogenic strain-sensing and functional-healing ability. This work provides a viable approach to fabricate ultrarobust subzero healable glassy polymers that are applicable for winter sports wearable devices, subzero temperature-suitable robots and artificial muscles. Self-healing materials hold great promise for applications in wearable electronics, artificial muscles and soft robots but selfhealing at subzero temperatures remains a great challenge. Here, the authors present a robust subzero healable glassy polymer by incorporating polyphenol nano-assemblies with a large number of end groups into polymerizable deep eutectic solvent elastomers.

Supercooled droplet freezing on surfaces occurs frequently in nature and industry, often adversely affecting the efficiency and reliability of technological processes. The ability of superhydrophobic surfaces to rapidly shed water and reduce ice adhesion make them promising candidates for resistance to icing. However, the effect of supercooled droplet freezing—with its inherent rapid local heating and explosive vaporization—on the evolution of droplet–substrate interactions, and the resulting implications for the design of icephobic surfaces, are little explored. Here we investigate the freezing of supercooled droplets resting on engineered textured surfaces. On the basis of investigations in which freezing is induced by evacuation of the atmosphere, we determine the surface properties required to promote ice self-expulsion and, simultaneously, identify two mechanisms through which repellency falters. We elucidate these outcomes by balancing (anti-)wetting surface forces with those triggered by recalescent freezing phenomena and demonstrate rationally designed textures to promote ice expulsion. Finally, we consider the complementary case of freezing at atmospheric pressure and subzero temperature, where we observe bottom-up ice suffusion within the surface texture. We then assemble a rational framework for the phenomenology of ice adhesion of supercooled droplets throughout freezing, informing ice-repellent surface design across the phase diagram.Icephobic surfaces are helpful for increasing safety and sustainability in engineering applications. A study of the behaviour of supercooled droplets freezing on superhydrophobic surfaces now provides insights into ice-repellency mechanisms.

Aqueous rechargeable metal‐ion batteries (ARMBs) represent one of the current research frontiers due to their low cost, high safety, and other unique features. Evolving to a practically useful device, the ARMBs must be adaptable to various ambient, especially the cold weather. While much effort has been made on organic electrolyte batteries operating at low temperatures, the study on low‐temperature ARMBs is still in its infancy. The challenge mainly comes from water freezing at subzero temperatures, resulting in dramatically retarded kinetics. Here, the freezing behavior of water and its effects on subzero performances of ARMBs are first discussed. Then all strategies used to enhance subzero temperature performances of ARMBs by associating them with battery kinetics are summarized. The subzero temperature performances of ARMBs and organic electrolyte batteries are compared. The final section presents potential directions for further improvements and future perspectives of this thriving field. Based on the freezing behavior of water and its effects on subzero performances of aqueous rechargeable metal‐ion batteries (ARMBs), strategies used to enhance subzero performance of ARMBs by associating them with battery kinetics are summarized. The subzero performance of ARMBs and organic electrolyte batteries are compared. Future perspectives of this thriving field are presented.

HighlightsA critical assessment of electrolytes’ limiting factors, which affect the low-temperature performance of Li-metal batteries.Summary of emerging strategies to improve low-temperature performance from the aspects of electrolyte design and electrolyte/electrode interphase engineering.Perspectives and challenges on how to develop creative solutions in electrolytes and correlative materials for low-temperature operation.Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes’ limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries.

Aqueous zinc-ion batteries (ZIBs) have attracted immense attention for flexible energy storage devices due to their high safety and low cost. However, conventional flexible aqueous ZIBs will undergo severe capacity loss at subzero temperature due to the inevitably freeze of electrolytes. In addition, under large bending or stretching strains, the encapsulation of devices would be damaged, which causes the evaporation of water in electrolytes and results in device failure. Herein, an anti-freezing and anti-drying gel electrolyte based on polyacrylamide (PAM) and glycerol (Gly) is developed. The strong hydrogen-bonding interactions between PAM or Gly and water molecules not only avoid the crystallization of the gel electrolyte at low temperatures, but also constrain the free water and restrict its evaporation. Therefore, such gel electrolyte displays a high ionic conductivity of 9.65 × 10−5 S cm−1 at −40°C. Furthermore, it can restrict the dehydration process when the electrolyte is exposed to ambient environment. The flexible ZIBs based on such gel electrolyte exhibit excellent electrochemical performance at −40°C and the devices without encapsulation retain 98% of their initial capacity in ambient condition after 30 days. This work provides a route to design anti-freezing and anti-drying gel electrolytes for aqueous energy storage devices.

Freeze desalination (FD) has several benefits compared to vaporization-based and membrane-based desalination methods. The FD process needs approximately 1/7th of the latent heat required by the vaporization-based desalination processes. The involvement of sub-zero temperature in FD reduces the risk of corrosion and scaling. This paper reviews the advances in FD methods involving stand-alone and hybrid methods that operate with and without utilizing the energy released during the re-gasification of liquefied natural gas. Moreover, the paper discusses the future focus areas for research and development to make FD a commercially feasible technology. Potable water was produced from brackish water and seawater by FD wherein the nucleation was achieved by ice seeding, the mixing of rejected salt from ice into the liquid phase was controlled appropriately, growth of ice crystals was slow, and liquid subcooling was maintained at approximately 4 K. The post-treatment of obtained ice is needed to produce potable water if the process is instigated without ice seeding. The plant capacity of stand-alone progressive FD was higher than the stand-alone suspension FD of seawater. The integration of the falling-film, fractional thawing, and block FD method showed significantly improved plant capacity than the stand-alone suspension FD method. The energy consumption of stand-alone PFC and SFC-based desalination with latent heat recovery was reported close to the reverse osmosis (RO) method. The hybrid (integration of the suspension FD method with membrane distillation) FD method utilizing LNG cold energy consumed less energy than the conventional RO method.

Highlights The unique layered structure and excellent photoelectric properties of MoS 2 facilitate the abundant generation and rapid transfer of photo-excited carriers, which accelerate the CO 2 reduction and Li 2 CO 3 decomposition upon illumination. MoS 2 -based photo-energized Li–CO 2 battery displays ultra-low charge voltage of 3.27 V, high energy efficiency of 90.2%, superior cycling stability after 120 cycles and high rate capability. The low-temperature Li–CO 2 battery achieves an ultra-low charge voltage of 3.4 V at –30 °C with a round-trip efficiency of 86.6%. Li–CO 2 batteries are considered promising energy storage systems in extreme environments such as Mars; however, severe performance degradation will occur at a subzero temperature owning to the sluggish reaction kinetics. Herein, a photo-energized strategy adopting sustainable solar energy in wide working temperature range Li–CO 2 battery was achieved with a binder-free MoS 2 /carbon nanotube (CNT) photo-electrode as cathode. The unique layered structure and excellent photoelectric properties of MoS 2 facilitate the abundant generation and rapid transfer of photo-excited carriers, which accelerate the CO 2 reduction and Li 2 CO 3 decomposition upon illumination. The illuminated battery at room temperature exhibited high discharge voltage of 2.95 V and mitigated charge voltage of 3.27 V, attaining superior energy efficiency of 90.2% and excellent cycling stability of over 120 cycles. Even at an extremely low temperature of − 30 °C, the battery with same electrolyte can still deliver a small polarization of 0.45 V by the photoelectric and photothermal synergistic mechanism of MoS 2 /CNT cathode. This work demonstrates the promising potential of the photo-energized wide working temperature range Li–CO 2 battery in addressing the obstacle of charge overpotential and energy efficiency.