Erythritol, with a high melting enthalpy of similar to 340 J g(-1), is promising for mid-temperature thermal energy storage, but suffers from poor thermal stability due to oxidative chain reactions on its hydroxyl groups. Here, we tackle this practical challenge by proposing a radical-trapping-based dual-protection strategy that combines nitrogen and an antioxidant. We identify the best antioxidant (AO1010), and show that solely using the antioxidant or nitrogen can only achieve limited improvements, because the unavoidable tiny amount of leaked oxygen molecules from the nitrogen "barrier" can still trigger the chain reactions, and the antioxidant "soldiers" will be constantly depleted upon trapping the intermediate radicals. Using this "barrier + soldier" strategy, we achieve an ultralong lifespan for erythritol with >83% enthalpy retention after heating at 150 degrees C for 10 000 hours and >90% after 1000 cycles. This strategy enables erythritol-based thermal batteries to have comparable capacity and lifespan to commercial lithium batteries, and can be generalizable to the broad sugar alcohol family and other organic PCMs.

The limitations of ion transport kinetics in conventional electrolytes, particularly under extreme operating conditions, arise from suboptimal solvation structures and inefficient charge carrier utilization. Here, we present strategic electrolyte design that reconfigures Li⁺ coordination geometry by modulating intermolecular interactions and solvent molecule volume, fundamentally overcoming these transport constraints. By incorporating an optimized moderator with a low dipole moment and small molecular size, extensive anion aggregation is effectively disrupted into compact ion conduction domains, simultaneously increasing the number of free charge carriers and enhancing ion mobility. Guided by this principle, the designed electrolyte with dichloromethane (85.11 Å, 2.36 Debye) exhibits rapid Li+ hopping between adjacent coordination sites (152.3 ps for acetonitrile and 115.7 ps for FSI-). This electrolyte enables stable cycling of 1.0 Ah 4.5 V graphite (3.13 mAh cm-2)||LiNi0.8Mn0.1Co0.1O2 (2.85 mAh cm-2) pouch cells, delivering 0.87 Ah at -40 °C, surpassing commercial carbonate-based electrolytes, which fail to retain reversible capacity at this temperature. This study establishes fundamental principles for fast ion-transport electrolytes, paving the way for next-generation Li-ion batteries under extreme scenarios.

Industrial activities, such as alumina production, generate abundant gaseous waste heat and pollutants, but their utilization efficiency is limited by its temperature grade and NOx. Latent heat storage (LHS) technology, which employs energy-intensive phase-change materials (PCMs) to recover waste heat from flue gases and release it for future use, can improve thermal efficiency via the heat-to-heat mode. Here, machine learning models, including Decision Trees, Random Forests, LightGBM, and Extra Tree, were developed based on 7 system variables to predict heat charging performance, with the Extra Tree model performing the best, as verified by experiments. The interpretive results indicate that the PCM volume, heat-transfer area, and degree of superheat primarily determine the heat charging time. Inspired by the lantern structure, a novel LHS system was proposed and analyzed for the Nusselt number and pressure drop through steady-state simulations. After analyzing various parameters including the fin count, PCM type, gas velocity, and fin angle, transient PCM melting simulations were then conducted by connecting the thermal boundaries to evaluate the optimal design. Compared to traditional designs, the proposed design reduces melting time by 43%, reduces gas-side thermal resistance by 49%, and maintains total thermal resistance at 5 °C/W. The state of charge (SOC) increases proportionally with time (SOC ∝ t), and reaches a high specific power of 139 W/kg and high latent heat storage capacity of 333.7 kJ/kg. Upon integration of machine learning, decoupled numerical simulations, thermal energy storage design, and system economic analysis, this work further unlocks the potential of using thermal storage to improve the effectiveness of industrial waste heat recovery.

Solar heating in high-irradiance, cold regions like the Tibetan Plateau and Iberian Peninsula often struggles with severe seasonal supply-demand mismatches. To address this, we propose a solar PV/T system integrated with seasonal latent heat storage using highly-supercooled phase change materials. Unlike sensible heat storage, this solution offers superior energy density and greater flexibility, leveraging stable supercooling to store heat with minimal insulation. Optimizations based on the Hangzhou indicated the system achieved a competitive levelized cost of electricity of 0.68 CNY/kWh, while a demonstration setup has been in continuous operation. Crucially, applying this system to the target region of Lhasa yields a global warming potential nearly 30% lower than in Hangzhou. Given the strong climatic parallels between Lhasa and Madrid, this study demonstrates the technology’s promising scalable potential for decarbonized heating in Iberia.

The high heat storage density of erythritol, originated from the hydrogen bonds formed by its hydroxyl structures, makes it a promising phase change material (PCM) in the medium temperature range. To further speed up the heat charging/discharging rates, increased thermal conductivity of erythritol can be realized by doping highly thermally-conductive fillers. However, the addition of fillers also reduces significantly the heat storage density as a penalty. To address this compromise issue, here we propose to use hydroxylated boron nitride nanosheets (-OH BNNSs) as the fillers. The creation of great number of hydrogen bonds between the hydroxyl groups on BNNS and the matrix PCM that is rich in hydroxyl structures builds up an additional heat conduction path and serves as a compensation for the loss of heat storage density. We show that the thermal conductivity of erythritol can be increased to 1.25 W/m center dot K at the loading of only 2 wt% -OH BNNSs. More importantly, compared with the loss of 12.7 % and 12.5 % caused by adding h-BN and BNNSs at the same loading, the loss of heat storage density of erythritol caused by -OH BNNSs is only 7.7 %, with the supercooling behavior of erythritol being also suppressed as an extra bonus.

Phase change materials (PCMs) for thermal energy storage require both high latent heat and high thermal conductivity, which is almost infeasible because the energy-dense materials are usually poor heat conductors, and increasing their thermal conductivity by making composites inevitably leads to a sacrifice in latent heat. Here, we propose a strategy for recovering the unavoidable loss of energy density of a composite PCM by strengthening the molecular connections between the fillers and matrix PCM. Taking erythritol (a polyol rich in hydroxyl groups) as an example, we use hydroxyl-modified nanofillers to reconstruct the filler-to-PCM intermolecular hydrogen bonds. Compared to unmodified graphene, we observe a remarkable recovery in the latent heat of erythritol using hydroxylated graphene, and verify the extension of this strategy to acids and hydrated salts. We show an almost full recovery of the energy density loss for composite erythritol at 1 wt.% loading, reaching an ultrahigh latent heat of fusion (328.5±0.9 J g-1). Using molecular simulations, we confirm the formation of strong hydrogen bonds between the model PCM molecules and hydroxylated graphene. Our strategy enables the development of polyol-based composite PCMs, which can be generalized to other matrix PCMs, toward more balanced performance in high energy density and power density.

Incorporation of long-term heat storage in solar heating systems is deemed to be a way to tackle the seasonal mismatch between abundant solar energy in summer and strong heating demand in winter, e.g., in western China. To make up the adaptability of existing implementation of sensible heat storage, here we propose a new type of solar photovoltaic/thermal (PV/T) system integrated with seasonal latent heat storage (SLHS), using a highly-supercooled phase change material (PCM), at an energy-denser and more flexible manner. Starting from the configuration of a demonstration setup built in Hangzhou, China, the thermal performance of this system was studied numerically using TRNSYS. The efficacy of the system, equipped with a 12 m(2) PV panel and a PCM-based SLHS unit of 15.6 GJ capacity, was confirmed for being able to supply hot water with daily average of 229 MJ and to maintain the room temperature at similar to 20 degrees C for a 20 m(2) heating area during the three-month heating season. Comparative simulations were also conducted for Lhasa, China, which is a representative targeted area. Not surprisingly, running this system in Lhasa can lower the global warming potential by nearly 30 %. With increasing the PV panel size the system can become self-sustained for off-grid users. After optimization of the PV panel size and SLHS unit capacity, the annual average coefficient of performance of the system can be improved by 160 % and the levelized cost of electricity can be reduced to only 0.68 CNY/kWh, showing great potential for practical applications toward decarbonized heating.

The application of phase change materials (PCM) in facility agriculture thermal energy storage is limited by the inability to effectively control heat absorption and release. Traditional PCM thermal storage systems rely on natural heat exchange, resulting in rapid enthalpy dissipation under low-temperature conditions, which fails to meet facility agriculture insulation demands. At present, the research gap is that the application of closed-loop control algorithms for regulating heat absorption and release in phase change thermal storage systems for facility agriculture remains unexplored. This study innovatively proposes a simplified heat transfer model for phase change thermal storage materials based on the Stefan equation. Subsequently, numerical simulations were conducted using this model, and a pioneering comparative study was performed to evaluate the control performance of Model Predictive Control (MPC), Proportional Control (P), and Proportional-Integral-Derivative Control (PID) in phase change thermal storage systems for facility agriculture. This research compares the control capabilities of MPC, P, and PID in maintaining a steady-state enthalpy target, tracking a dynamic enthalpy target, and operating under external disturbances. The results indicate that: 1) Under a constant target, the stabilization speed of MPC is 1.86 times that of P and 3.67 times that of PID; 2) For dynamic targets, the tracking RMSE of MPC is 1.77 % of that of PID and 2.25 % of that of P.; 3) Under external disturbances, the output RMSE of MPC is 10.36 % of that of PID and 9.02 % of that of P. Finally, a closed-loop control experiment on PCM enthalpy was conducted to verify the feasibility of MPC in stabilizing the enthalpy of phase change materials. The findings demonstrate that MPC-based enthalpy control enhances PCM energy utilization, reduces passive thermal storage losses, and improves temperature regulation efficiency in greenhouse applications.

Li-ion batteries (LIBs) for electric vehicles and aviation demand high energy density, fast charging and a wide operating temperature range, which are virtually impossible because they require electrolytes to simultaneously have high ionic conductivity, low solvation energy and low melting point and form an anion-derived inorganic interphase 1 – 5 . Here we report guidelines for designing such electrolytes by using small-sized solvents with low solvation energy. The tiny solvent in the secondary solvation sheath pulls out the Li + in the primary solvation sheath to form a fast ion-conduction ligand channel to enhance Li + transport, while the small-sized solvent with low solvation energy also allows the anion to enter the first Li + solvation shell to form an inorganic-rich interphase. The electrolyte-design concept is demonstrated by using fluoroacetonitrile (FAN) solvent. The electrolyte of 1.3 M lithium bis(fluorosulfonyl)imide (LiFSI) in FAN exhibits ultrahigh ionic conductivity of 40.3 mS cm −1 at 25 °C and 11.9 mS cm −1 even at −70 °C, thus enabling 4.5-V graphite||LiNi 0.8 Mn 0.1 Co 0.1 O 2 pouch cells (1.2 Ah, 2.85 mAh cm −2 ) to achieve high reversibility (0.62 Ah) when the cells are charged and discharged even at −65 °C. The electrolyte with small-sized solvents enables LIBs to simultaneously achieve high energy density, fast charging and a wide operating temperature range, which is unattainable for the current electrolyte design but is highly desired for extreme LIBs. This mechanism is generalizable and can be expanded to other metal-ion battery electrolytes.

Abstract Seasonal storage of solar thermal energy through supercooled phase change materials (PCM) offers a promising solution for decarbonizing space and water heating in winter. Despite the high energy density and adaptability, natural PCMs often lack the necessary supercooling for stable, long-term storage. Leveraging erythritol, a sustainable mid-temperature PCM with high latent heat, we introduce a straightforward method to stabilize its supercooling by incorporating carrageenan (CG), a bio-derived food thickener. By improving the solid-liquid interfacial energy with the addition of CG the latent heat of erythritol can be effectively locked at a very low temperature. We show that the composite PCM can sustain an ultrastable supercooled state below −30 °C, which guarantees no accidental loss of the latent heat in severe cold regions on Earth. We further demonstrate that the common ultrasonication method can be used as the key to unlocking the latent heat stored in the CG-thickened erythritol, showing its great potential to serve as a high-performance, eco-friendly PCM for long-term seasonal solar energy storage.

Sugar alcohols have been proposed as a class of potential phase change materials (PCMs) for mediumtemperature latent heat storage. The present work investigated the cycling stability of four pure and three mixture sugar alcohols by a specially-designed test setup, followed by a comprehensive evaluation based on their phase change behaviors (reported in our previous publication) and stability. It was found that the latent heats of fusion/crystallization degrade upon consecutive melting-crystallization cycles, and a higher degree of superheat Delta T-sh leads to a faster degradation. An extremely low level of only 10.5 % degradation was obtained for erythritol after 200 cycles at a relatively low Delta T-sh of 20 degrees C. The corresponding degrees of supercooling Delta Tsc become higher due to the remarkable reduction of crystallization temperatures. It was shown that introducing protective nitrogen gas could suppress oxidation and improve cycling stability. The cycles of half degradation on latent heat of fusion was similar to 3.6 times with nitrogen protection. A comprehensive evaluation identified that the crystallization-related issues and poor stability are the primary challenges for sugar alcohols. Nevertheless, other than common PCMs, some particular application scenarios like controllable latent heat retrieval and seasonal heat storage can be hopefully developed by virtue of the deep supercooling nature of sugar alcohols.

The adoption of appropriate phase change materials (PCMs) is deemed to be the primary step during the course of application of latent heat storage technology. As a class of potential candidates, sugar alcohols are suitable for latent heat storage over medium temperature range (80-230 degrees C). The present work attempts to provide a comprehensive overview on the phase change behaviors, transport properties, thermal stability, charging/dis-charging performance and application status of sugar alcohols based on adequate amount of available in-vestigations. Special attention is paid to their peculiar crystallization behaviors including supercooling, non -crystallization and cold-crystallization. In particular, the intrinsic mechanisms responsible for the above be-haviors and properties are fully discussed, and some suitable techniques for alternating such behaviors/prop-erties have been proposed accordingly. The specific advantages like high heat storage density and challenges such as poor thermal endurance are completely summarized for sugar alcohols. Furthermore, the potential application scenarios associated with long-term heat storage and controllable heat retrieval are put forward on the basis of the particular properties. Future studies with emphasis on the underlying fundamentals of crystal-lization and chemical reactions concerned with thermal stability are suggested. This review aims at building a benchmark database on the key information of sugar alcohol PCMs, thus to help deeply understand their properties. It can also provide useful guidelines to facilitate the large-scale utilization of sugar alcohols in solar thermal energy harvesting and industrial waste heat recovery.

Recovering medium-temperature (e.g., 150-180 degrees C) industrial waste heat through latent heat thermal energy storage (LHTES) can effectively attenuate the consumption of fossil fuels. However, the LHTES system containing a single medium-temperature phase change material (PCM), e.g., erythritol, cannot absorb the part of heat below the PCM's melting point (-118 degrees C) during the charging process. Meanwhile, a single low-temperature PCM, e.g., paraffin wax, is unable to supply a significant amount of heat at temperatures higher than its melting point upon discharging. Therefore, a cascade LHTES system combining one erythritol unit and two paraffin wax units (melting point of-60 degrees C) was proposed to deeply recover the waste heat during charging and increase the heat supply temperature during discharging. Through prototype testing, the performance of such a cascade system was examined under various working conditions. It was shown that the cascade system could improve the ef-ficiency of the waste heat recovery from 15.8% to 63.4% under the charging condition of 100 L/h and 160 degrees C, as compared to a single-stage erythritol-based system. The average heat supply temperature of the cascade system was also increased from 37 degrees C (at a constant flow rate) to 53.6 degrees C via an active discharging strategy (by tuning the flow rate). This highly efficient cascade LHTES system has great potential for recovery of medium -temperature waste heat towards a decarbonized future of space heating for buildings.

The aim and objective of this review is to intensively summarize composite film materials that can achieve thermal radiation insulation without affecting visible light transmittance, in order to reduce the heat loss in greenhouses and thus save energy. Eight kinds of composite films, which could be used for radiation insulation, were finally determined and intensively reviewed by searching the key words including insulation film, insulation agent, and infrared insulation. These materials can be divided into two categories: silica/poly and zinc oxide/poly composites. The radiation thermal insulation property and light transmission property of these materials were experimentally tested by spectrometry. The key finding of this article includes that phonon resonance and Anderson localization could be used to block thermal infrared radiation by generalizing material properties. The conclusion of this review is that those materials have at least a 10% increase in infrared thermal radiation blocking, but only a small decrease in visible light transmittance.

The agricultural greenhouse section takes up the largest part of total final energy consumption in agriculture in the majority of countries. This review focuses on the applications of phase change materials in agricultural greenhouses aiming at energy conservation and providing a comfortable environment for crops’ growth and development. The significance of this article is to offer valuable guidance for choosing proper PCMs for agricultural greenhouse applications and how to appropriately use various PCMs for special scenarios in greenhouses. The research method covers how to search and determine valuable literature of PCM applications in greenhouses recently using incorporating various keyword combinations via popular database sources. . The research content includes the section of results reviews types of PCMs, thermo-physical properties, life cycles of PCMs, PCMs applications in greenhouses, parametric sensitivity study, PCM performance in greenhouses and mathematical models, respectively. The main research conclusions have been drawn that (1) Different from PCM applications in human-occupied buildings, thermal requirement of crop growth between day and night is adequately considered, the PCM melting temperature should be close to each crop’ individual suitable growing temperature; (2) the main type of PCM used in greenhouses is paraffin wax and paraffin wax-based composite, which accounts for 30% of selected literature.

Erythritol, having a nominal melting point of similar to 118 degrees C, has been considered a candidate phase change material (PCM) for medium-temperature thermal energy storage (TES) due to its large latent heat of fusion (similar to 330 kJ/kg). However, it suffers from severe supercooling effect, up to several tens of degrees Celsius, upon crystallization by cooling, which remains to be a critical issue for its application. Here we propose a novel method of injection of gas bubbles into subcooled liquid erythritol to facilitate the nucleation of erythritol crystals, so as to reduce its degree of supercooling. Using this method, we obtained successfully an unprecedented reduction of the degree of supercooling of erythritol down to only 5 degrees C, which is much lower than those achieved by other conventional methods like adding a nucleating agent or ultrasonication. As a bonus, the latent heat of crystallization was found to be greatly increased by nearly 50%, from 218.2 kJ/kg to 322.3 kJ/kg. The injection of bubbles also enables an effective way for actively triggering the crystallization of erythritol in a controllable manner. Our results showed that by changing the injecting timing of bubbles, crystallization can always be triggered immediately with only the crystallization point being varied over a wide range. The injection of bubbles is thus deemed to be a highly efficient, cost-effective, and scalable method for addressing the supercooling issue of erythritol, and other similar PCMs with deep supercooling, making it more promising for TES applications.

The supercooling effect is deemed to be a crucial issue for thermal energy storage using phase change materials (PCMs). The exploration of promising additives plays a decisive role in effective suppression efforts for suppressing the supercooling effect of a PCM. The present work proposed a potential additive, polyvinylpyrrolidone (PVP), to reduce the supercooling of erythritol, which is the most promising polyol PCM candidate for medium temperature range. PVP with various loadings was dispersed in erythritol to make composites for the proof-of-concept tests. It was shown that the degree of supercooling of erythritol can be reduced significantly from over 64 ? to about 21 ? in the presence of only 1.0 wt.% PVP. Along with the mitigated supercooling effect, the addition of PVP also leads to an increase of the retrievable latent heat during crystallization, from ~187 J/g to ~224 J/g at the same minute PVP loading of 1.0 wt.%, by increasing the crystallinity of erythritol. The PVP-loaded erythritol composites exhibit little sacrifice in latent heat of fusion, i.e., only ~15% loss when the PVP loading reaches 6.0 wt.%. In addition, multiple tests confirmed that PVP can be dissolved in erythritol, thus desirable compatibility was obtained and the composites would have long-term reliability. This proposed additive enables an efficient and cost-effective way for improving the crystallization behaviors of erythritol (and other polyol PCMs) towards real-world applications.

Wetland restoration is an effective way to recover degraded wetlands worldwide. The Dongting Lake wetland, an important wintering habitat for waterbirds, has suffered considerable degradation due to climate change and human disturbance during the last two decades; however, wetland restoration projects have now been implemented to improve waterbird diversity in the Dongting Lake. Based on annual waterbird and habitat survey data (2012/2013–2019/2020), we aimed to compare the differences in habitat variables (e.g., sedge [Carex spp.] meadow area, mudflat area, water area, and the normalized difference vegetation index of the sedge [Carex spp.] meadow) between the restored and unrestored wetlands to confirm whether wetland restorations could improve habitat quality. We also evaluated whether wetland restoration could effectively improve waterbird diversity by comparing the differences in waterbird populations at the community, foraging guild, feeding habitat guild, and species levels in the restored and unrestored wetlands. The results indicated that the restored wetland could provide more diverse and suitable habitats than the unrestored ones, particularly in terms of a sufficient variety of water habitats of different depths for waterbirds. The restored wetland was able to support substantial and diverse waterbird populations during the winter season. Specifically, compared to the unrestored wetlands, the restored wetland generally had higher species richness, individual density, and Shannon–Wiener diversity index at the community level; higher densities or proportions of different foraging guilds (tuber feeders, herbivores, fish eaters, insectivores, and omnivores, except herbivores geese), and of different feeding habitat guilds (G [0–10 cm], G (20–50 cm), G (20–70 cm), and G (>70 cm) guilds); and higher densities or proportions of the target species (except the lesser white-fronted goose and bean goose) at the species level. The larger waterbird populations in the restored wetland might be closely related to suitable crucial habitats, as indicated by positive correlation between their abundance and suitable habitat areas. Creating diverse suitable habitats for waterbirds, according to their habitat requirements, should be the first consideration in future wetland restorations. These findings provide a basis for wetland restoration and protection of wintering waterbird diversity in the Dongting Lake as well as in the middle and lower reaches of the Yangtze River floodplain.

The temperature-dependent rheological behaviors of five selected binary eutectic mixture sugar alcohols, with great potential for latent heat storage in the range of 353.15 K to 523.15 K, were investigated. It was found that the rheological behaviors of the mixture sugar alcohols depend on those of the pure compounds as well as their molar ratios. The two mixtures of xylitol(75 mol%)+erythritol and erythritol(84 mol%)+d-mannitol behave like pseudoplastic fluids with typical non-Newtonian shear-thinning behaviors, as indicated by the power law index of 0.99(<1). The mixture of d-mannitol(70 mol%)+d-dulcitol is a nonlinear Bingham fluid, exhibiting a slight yield stress(0.001 Pa to 0.01 Pa) at low shear rates. The rest two mixtures containing the cyclic-structured inositol behave like Herschel-Bulkley fluids. The infinite shear viscosities of the eutectic mixtures over the entire temperature range appear to be higher than those of their respective pure compounds, except for inositol. The mixture of xylitol(75 mol%)+erythritol at its melting point shows higher dynamic viscosity of about 0.546 Pa·s than the values of about 0.396 Pa·s and 0.035 Pa·s for xylitol and erythritol, respectively. In addition, the activation energies of viscous flow of the mixtures, as determined by fitting the dynamic viscosity-temperature curves using the Arrhenius model, also exhibit higher values than those of their pure compounds. The activation energy of viscous flow of the mixture xylitol(75 mol%)+erythritol was determined to be about 92 400 J/mol in the supercooled liquid state, while the supercooled liquid xylitol and erythritol have much lower values of 83 500 J/mol and 51 900 J/mol, respectively. Both the increased dynamic viscosities and activation energies of viscous flow can result in deteriorated crystallization performance during latent heat retrieval.