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Nickel chloride (NiCl2) is considered an excellent cathode material for thermal batteries because of its high specific capacity and operating voltage. However, low conductivity and the melt overflow of the electrode material greatly limit the practical application of NiCl2 cathode material. Herein, in this work, a NiCl2-based cathode material featuring a structurally disordered nanoscale nitrogen-doped carbon (N–C) skin structure, synthesized through high-temperature carbonization of melamine and sucrose. The N–C surface-modified NiCl2 nanocomposite demonstrates a specific energy of up to 630.63 W h·kg–1 and low internal resistance of 0.157 Ω at 300 mA·cm–2, with an effective reduction in average internal resistance of 40.00% compared to NiCl2. This improvement is attributed to the doping of heteroatomic nitrogen, which results in the formation of vacancy defects and active sites within the carbon material, thereby effectively improving the electrical conductivity of NiCl2. Furthermore, the nanoscale N–C modification layer acts as a protective barrier to inhibit the adverse reactions between NiCl2 and electrolyte, thus reducing melt overflow from the electrode. This strategy of nanoscale heteroatom-doped carbon surface modification was inaugural applied to NiCl2 cathode materials, yielding promising outcomes, providing a potential reference for optimizing the performance of other electrode materials. [ABSTRACT FROM AUTHOR]

A copper fluoride with small size and high purity is very important to present its ability as a cathode material for lithium thermal batteries (LTBs). In this paper, we investigate the effect of the heat treatment temperature of the precursor ammonium copper fluoride on the preparation of a high-performance copper fluoride cathode. The color of CuF2 gradually changes from white to dark brown as the heat treatment temperature of the ammonium copper fluoride precursor is increased due to the change in dimensions and morphology. The CuF2-250 prepared at the heat treatment temperature of 250 ℃ has a small D50 particle size of 1.838 µm (agglomeration of particles from 50 to 100 nm), high purity, large BET surface area of 16.3649 m2/g, and excellent working properties. Its operating voltage reached as high as 3.5 V in the initial activation stage at a discharge current density of 500 mA/g, which is attributed to the better conductivity caused by its small size favorable shortened Li+ diffusion path, and its specific capacity and discharge time at the cut-off voltage of 1.5 V were 498 mAh/g close to 94% of the theoretical specific capacity (528 mAh/g) and ultralong 3585 s, respectively. This study provides a guideline for the development of high-performance cathode materials for LTBs. [ABSTRACT FROM AUTHOR]

Recently, there has been an increasing demand for high-voltage thermal batteries. FeF 3 has a high open-circuit voltage of 2.7 V and is gaining attention as a potential alternative. However, it involves the problem of a low electrical conductivity owing to the wide band gap (5.96 eV) and the generation of lithium fluoride (LiF), which is a discharge product in the conversion reaction. To address this issue, acetylene black with high conductivity is utilized to enhance the electrochemical activity of metal fluoride (FeF 3). At present, FeF 3 /AB is produced by low- and high-collision-energy ball milling. These are mechanical milling methods that involve different collision energies. High-collision-energy ball milling has been demonstrated to degrade the electrochemical performance owing to crystal deformation. In contrast, low-collision-energy ball milling has demonstrated the potential for application in thermal batteries by minimizing crystal deformation and enhancing the electrical conductivity. In this study, the amount of added carbon was optimized to enhance the performance of thermal battery materials. Both low- and high-collision-energy ball-milling processes exhibited remarkable thermal stability when 5.0 wt% carbon was added. However, the high-collision-energy ball-milling process did not effectively enhance the thermal cell performance because the electrical conductivity did not increase significantly. Therefore, FeF 3 /5.0 wt% AB produced by low-collision-energy ball milling exhibited remarkable thermal stability and electrical conductivity. This indicates its potential for use in thermal batteries. [ABSTRACT FROM AUTHOR]

Over 50% of an engine's energy dissipates via the exhaust and cooling systems, leading to considerable energy loss. Effectively harnessing the waste heat generated by the engine is a critical avenue for enhancing energy efficiency. Traditional exhaust heat recovery systems are limited to real-time recovery of exhaust heat primarily for engine warm-up and fail to fully optimize exhaust heat utilization. This paper introduces a novel exhaust heat recovery system leveraging thermal battery technology, which utilizes phase change materials for both heat storage and reutilization. This innovation significantly minimizes the engine's cold start duration and provides necessary heating for the cabin during start-up. Dynamic models and thermal management system models were constructed. Parameter optimization and calculations for essential components were conducted, and the fidelity of the simulation model was confirmed through experiments conducted under idle warm-up conditions. Four distinct operational modes for engine warm-up are proposed, and strategies for transitioning between these heating modes are established. A simulation analysis was performed across four varying operational scenarios: WLTC, NEDC, 40 km/h, and 80 km/h. The results indicated that the thermal battery-based exhaust heat recovery system notably reduces warm-up time and fuel consumption. In comparison to the cold start mode, the constant speed condition at 40 km/h showcased the most significant reduction in warm-up time, achieving an impressive 22.52% saving; the highest cumulative fuel consumption reduction was observed at a constant speed of 80 km/h, totaling 24.7%. This study offers theoretical foundations for further exploration of thermal management systems in new energy vehicles that incorporate heat storage and reutilization strategies utilizing thermal batteries. [ABSTRACT FROM AUTHOR]

One of the key issues confronting modern greenhouses is the need to supply the necessary energy in an environmentally friendly manner to facilitate heating and cooling processes within greenhouses. Solar radiation entering the greenhouse during the day can sometimes be more than the energy demand of the greenhouse. In contrast, there are cases where the greenhouse must dissipate a significant amount of heat, absorbed over a long period, either naturally or forcibly, during the cooling process. Moreover, the system's efficiency could be enhanced if there is a mechanism capable of capturing heat expelled during greenhouse cooling and redistributing it on demand. Employing thermal energy storage is critical for maintaining stable temperatures, assuring energy efficiency, encouraging sustainability, and enabling year-round production. This technique ensures a safe environment for crops and eliminates temperature fluctuations inside the greenhouse. Nocturnal thermal energy storage, storing thermal energy during the daytime for later use at night, is essential to managing a contemporary greenhouse because it promotes consistent crop growth, sustainability, and profitability, particularly in areas with severe winters and significant day-to-night temperature variations. This work reviews various types of thermal energy storage systems employed in previous works focusing on greenhouse applications by researchers and categorizes them based on efficient factors. [ABSTRACT FROM AUTHOR]

To address the typical structural defects that are prone to occur during the preparation and storage processes of thermal battery, experiments of battery image acquisition were designed based on X-ray computed tomography system. An improved Yolov5s network was employed to achieve high-precision automatic detection of typical defects. Through the discharge experiment of thermal battery, discharge performance curves of normal batteries and three defective batteries were constructed. The impact and mechanisms of different defects on the discharge performance were analyzed based on the voltage curve. By designing an automatic stitching scheme, the phenomenon of interlayer information overlap caused by the increase of cone angle in digital radiography images was suppressed. To address the issues of low image contrast and limited defect data in thermal battery imaging, the defect dataset was expanded using the designed image preprocessing steps and improving the contrast of the images. For subtle defects that are difficult to identify, the introduced multi-head self-attention mechanism in Transformer and the use of Focal Loss instead of cross-entropy loss function were employed to improve the recognition accuracy of subtle defects while ensuring the detection speed. The comparative experiment shows that the improved network model has higher recognition accuracy compared to Faster R-CNN, SSD, Cascade R-CNN, EfficientDet and the original Yolov5s network. The recognition accuracy of typical defects in thermal batteries can reach 98.7%. [ABSTRACT FROM AUTHOR]

Manufacturing thin‐film components is crucial for achieving high‐efficiency and high‐power thermal batteries (TBs). However, developing binders with low‐gas production at the operating temperature range of TBs (400–550 °C) has proven to be a significant challenge. Here, we report the use of acrylic acid derivative terpolymer (LA136D) as a low‐volatile binder for thin‐film cathode fabrication and studied the chain scission and chemical bond‐breaking mechanisms in pyrolysis. It is shown LA136D defers to random‐chain scission and cross‐linking chain scission mechanisms, which gifts it with a low proportion of volatile products (ψ, ψ = 39.2 wt%) at even up to 550 °C, well below those of the conventional PVDF (77.6 wt%) and SBR (99.2 wt%) binders. Surprisingly, LA136D contributes to constructing a thermal shock‐resistant cathode due to the step‐by‐step bond‐breaking process. This is beneficial for the overall performance of TBs. In discharging test, the thin‐film cathodes exhibited a remarkable 440% reduction in polarization and 300% enhancement in the utilization efficiency of cathode materials, while with just a slight increase of 0.05 MPa in gas pressure compared with traditional "thick‐film" cathode. Our work highlights the potential of LA136D as a low‐volatile binder for thin‐film cathodes and shows the feasibility of manufacturing high‐efficiency and high‐power TBs through polymer molecule engineering. [ABSTRACT FROM AUTHOR]

The activation of thermal batteries requires plentiful heat to melt the ambient solid electrolyte into an ionic conductor with high ionic conductivity for large current discharge. The process necessitates massive heating powder to provide heat, severely reducing the effective specific energy of the thermal battery. To decrease energy consumption, we developed the LiCl–LiBr–KBr–CsBr molten salt with low melting point of 239 °C, fusion enthalpy at 59.08 J/g, specific heat capacity of 0.38 J/K·g and 0.88 J/K·g in the solid and liquid states, correspondingly, which takes 44% less heat to reach the operating temperature (generally 500 °C) compared to the commonly used LiF–LiCl–LiBr electrolyte. These reductions not only enable the battery to discharge across a broad temperature range, but also lessens the quantity of pyrotechnic heating pellets and enhances the thermal battery's overall specific energy and safety. [ABSTRACT FROM AUTHOR]

The object of research is heat transfer in a hybrid thermal photovoltaic solar collector. International agreements and strategies aimed at combating climate change and reducing greenhouse gas emissions strongly call for the active implementation of renewable energy sources on a global scale. A special emphasis is placed on the development of solar energy, which has significant growth potential due to the constant improvement of technologies and cost reduction of production. With this in mind, the authors focused on the development and analysis of a computer model of an innovative hybrid system that effectively combines a solar collector for the simultaneous production of both thermal and electrical energy. The research included a detailed study of the temperature changes of the heat carrier in the hybrid photovoltaic solar collector and thermal accumulator during the period of solar irradiation. Thanks to careful monitoring, the main patterns of gradual temperature increase in both key components of the hybrid system were established. In addition, an assessment of the dynamics of changes in the instantaneous thermal power of the solar collector under the influence of various factors, such as the intensity of solar radiation, the angle of inclination of the collector, wind speed, etc., was carried out. The results of computer modeling showed the average indicator of the efficiency of the entire hybrid system, as well as its variations during a certain time of operation. In addition, the change in the instantaneous specific heat capacity and the overall efficiency of heat energy generation by the hybrid photovoltaic solar collector were analyzed. Special attention was paid to the study of the dynamics of changes in the thermal efficiency of the entire system, as well as its ability to efficiently store thermal energy in a specialized battery. The comprehensive analysis made it possible to obtain the key thermophysical parameters of the developed hybrid system with a photovoltaic solar collector. This data is extremely important, as it will allow engineers and scientists to accurately calculate the potential performance and efficiency of such a system when it is put into practical use in the future. In general, the results of the study emphasize the promising development of hybrid solar collectors as one of the leading technologies in the field of renewable energy in the context of global challenges of climate change. [ABSTRACT FROM AUTHOR]

Nickel chloride (NiCl2) is a typical hexagonal layered semiconductor material with wide application. However, it is mainly restricted by complicated technological process within ultrahigh dehydration temperature. Utilizing copper doping, a sort of high purity and remarkable crystallinity NiCl2 is fabricated using a simple low‐temperature calcination technique. The dehydration temperature is decreased from 600 to 400 °C because the adsorbed copper ions on NiCl2 dihydrate surface can weaken NiO bond strength. Serving for thermal battery cathode, copper‐doped NiCl2 exhibits remarkable discharge ability at 500 mA cm−2, equipped with supernormal power density of 16.27 kW kg−1 and energy density of 717 Wh kg−1 simultaneously. Its energy density is increased by 28% compared to NiCl2. Copper doping optimizes thermodynamics process of discharge reaction and modifies local electronic structure of NiCl2. For copper‐doped NiCl2, the shift of Ni 3d and Cl 3p to lower energy level results in elevated redox potential, and the reduction of bandgap accelerates the carrier mobility, further promoting discharge degree. Utilizing metal ions dopant, this research surmounts the low‐temperature synthesis of NiCl2 and addresses its inferior electrochemical performance, ensuring high energy‐power output. This will expand the application scenarios of NiCl2‐based cathode materials. [ABSTRACT FROM AUTHOR]

In the last three decades, many researchers have published their findings on the storage of thermal energy using various phase transition materials (both organic and non-organic). One of their goals was to have a higher heat storage capacity with a shorter heat charging cycle for thermal energy storage. This study looked into a floating capsule thermal energy storage system (TESS). A number of spherical capsules filled with beeswax were placed in a paraffin-filled cylindrical shell. With heat transfer fluid flowing through three hexagonal tubes arranged at 120° inside the TESS core, the two phase change materials (beeswax with a thermal conductivity of 0.25 W/mK and paraffin with a thermal conductivity of 0.23 W/mK) were charged and discharged. For the proposed TESS, a mathematical model was created and utilised to forecast thermal energy storage capacity and charging/discharge times for various configurations. In TESS, a 70-30% mixture of the two PCMs results in a 21.5 percent increase in heat storage capacity when beeswax alone is used, and an 8.4 percent decrease in storage capacity when paraffin alone is used. For a heat storage capacity of 7300 kJ, the model estimates charging and discharging times of around 2.6 and 3.2 hours, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates the thermal battery as a research topic. We conducted an in-depth analysis of various thermal battery aspects, such as the cathode material CoS2 and electrolyte material morphology, crystal type, and interface state changes before and after service. The aim was to explore the core reaction and main failure mechanisms of the thermal battery. Prior to the reaction, the thermal battery cathode and electrolyte material consisted of pure-phase CoS2 and a composition of MgO-LiF/LiBr/LiCl. After service, the cathode and electrolyte of the single thermal battery exhibited significant morphological alterations caused by the presence of a molten state. The cathode transformed from CoS2 to Co3S4 and Co9S8 together with the presence of a marginal quantity of Co monomers visible throughout the discharge process, which was confirmed by means of XRD and XPS analyses. After the reaction, the electrolyte material was primarily made up of LiF, LiBr, and LiCl while the crystal components remained largely unaltered, albeit with apparent morphological variations. As was deduced from the thermodynamic analysis, the cathode material's decomposition temperature stood at 655 °C, exceeding the working temperature of the thermal battery (500 °C) by a considerable margin, which is indicative of outstanding thermal durability within the thermal battery's operational temperature range. Furthermore, the discharge reaction of the positive electrode was incomplete, resulting in reduced CoS2 residue in the thermal battery monomer after service. The reaction yielded a combination of Co3S4, Co9S8, and small amounts of Co monomers, indicating possible inconsistencies in the phase composition of the pole piece during the reaction process. In this study, we examine the distribution of residual stress in the thermal battery under various operating conditions. The simulation results indicate that exposure to a 70 °C environment for 2 h causes the maximum residual stress of the battery, which had an initial temperature of 25 °C, to reach 0.26 GPa. The thermal battery subjected to an initial temperature of 25 °C exhibited a maximum residual stress of 0.42 GPa subsequent to a 2-hour exposure to a temperature of −50 °C. [ABSTRACT FROM AUTHOR]

Thermal energy storage systems, also known as thermal batteries integrated with phase change materials, have gained significant attention in recent years as a promising solution for sustainable energy supply. Thermal batteries can significantly promote a sustainable energy supply by boosting the efficiency and reliability of renewable energy systems, enhancing energy access in isolated regions, lowering greenhouse gas emissions, and enhancing energy security. However, there are still challenges to optimising these systems to maximise their efficiency and effectiveness. This study presents a systematic literature review of various thermal batteries for industrial, commercial, and domestic applications. The preferred reporting items for systematic reviews and meta-analyses guidelines were adopted for this review. The primary objective was to identify factors affecting thermal battery performance. Data collection was focused on research papers published from 2013–2023 extracted from the Scopus, Web of Science, and Google Scholar databases. The study findings highlight the importance of considering material thermophysical properties, design configurations, and operating conditions when optimising thermal batteries. Also, this study highlights the current state of knowledge in the field and suggests future research and development directions. In particular, artificial intelligence and machine learning are suggested to promote faster and more precise optimisation of thermal batteries. The findings of this study are useful to academia and industries promoting the adoption of sustainable energy solutions for a greener and more resilient future.

Over 50% of an engine’s energy dissipates via the exhaust and cooling systems, leading to considerable energy loss. Effectively harnessing the waste heat generated by the engine is a critical avenue for enhancing energy efficiency. Traditional exhaust heat recovery systems are limited to real-time recovery of exhaust heat primarily for engine warm-up and fail to fully optimize exhaust heat utilization. This paper introduces a novel exhaust heat recovery system leveraging thermal battery technology, which utilizes phase change materials for both heat storage and reutilization. This innovation significantly minimizes the engine’s cold start duration and provides necessary heating for the cabin during start-up. Dynamic models and thermal management system models were constructed. Parameter optimization and calculations for essential components were conducted, and the fidelity of the simulation model was confirmed through experiments conducted under idle warm-up conditions. Four distinct operational modes for engine warm-up are proposed, and strategies for transitioning between these heating modes are established. A simulation analysis was performed across four varying operational scenarios: WLTC, NEDC, 40 km/h, and 80 km/h. The results indicated that the thermal battery-based exhaust heat recovery system notably reduces warm-up time and fuel consumption. In comparison to the cold start mode, the constant speed condition at 40 km/h showcased the most significant reduction in warm-up time, achieving an impressive 22.52% saving; the highest cumulative fuel consumption reduction was observed at a constant speed of 80 km/h, totaling 24.7%. This study offers theoretical foundations for further exploration of thermal management systems in new energy vehicles that incorporate heat storage and reutilization strategies utilizing thermal batteries.

One of the key issues confronting modern greenhouses is the need to supply the necessary energy in an environmentally friendly manner to facilitate heating and cooling processes within greenhouses. Solar radiation entering the greenhouse during the day can sometimes be more than the energy demand of the greenhouse. In contrast, there are cases where the greenhouse must dissipate a significant amount of heat, absorbed over a long period, either naturally or forcibly, during the cooling process. Moreover, the system’s efficiency could be enhanced if there is a mechanism capable of capturing heat expelled during greenhouse cooling and redistributing it on demand. Employing thermal energy storage is critical for maintaining stable temperatures, assuring energy efficiency, encouraging sustainability, and enabling year-round production. This technique ensures a safe environment for crops and eliminates temperature fluctuations inside the greenhouse. Nocturnal thermal energy storage, storing thermal energy during the daytime for later use at night, is essential to managing a contemporary greenhouse because it promotes consistent crop growth, sustainability, and profitability, particularly in areas with severe winters and significant day-to-night temperature variations. This work reviews various types of thermal energy storage systems employed in previous works focusing on greenhouse applications by researchers and categorizes them based on efficient factors.

Heat charging and discharging performances and cycling stability of the coupled MgH 2 –LaNi 5 thermal storage system are investigated. Heat storage reaction is studied by tracking temperatures and pressures of hydride beds as well as hydrogen mass flow rates exchanging between MgH 2 and LaNi 5. Upon 20 heat storage cycles, MgH 2 –LaNi 5 pair reveals remarkably cycling stability with the energy densities during heat charging and discharging of 797 ± 37.5 and 680 ± 28 kJ/kg, respectively. The hydrogen content exchange between MgH 2 and LaNi 5 during heat storage cycles is up to 57 % of theoretical hydrogen capacity. The possibilities to enhance the hydrogen contents participating in the heat storage reaction are discussed. The heat charging and discharging performances at different positions in the hydride beds of MgH 2 –LaNi 5 pair are characterized. Not only thermodynamic compatibility of MgH 2 and LaNi 5 but also kinetics as well as hydrogen and heat transfer in MgH 2 beds considerably influence heat storage performance. • Heat dis/charging stability upon 20 cycles of MgH 2 –LaNi 5 pair is confirmed. • H 2 exchange reactions between MgH 2 and LaNi 5 upon heat storage cycles are studied. • T and ESD during heat discharging are up to 310 °C and 680 ± 28 kJ/kg, respectively. • Up to 57 % of theoretical H 2 capacity of MgH 2 participates in heat storage cycles. • Heat storage of MgH 2 depends on kinetics, H 2 diffusion, and thermal conductivity. [ABSTRACT FROM AUTHOR]

Escalating energy tariffs and peak cooling demands due to climate change along with expanding use of variable renewable energy supply are presenting new challenges and opportunities for air conditioning system operation and control. This research presents the outcome of an investigation into the use of a thermal battery using salt-hydrate phase change material (PCM) in commercial buildings. A 1.2 m3 modular thermal battery using 15 °C melting temperature salt-hydrate PCM has been designed and fabricated. Its cooling performance and feasibility of integration into a chilled water-cooling system of commercial buildings has been comprehensively investigated. This storage unit can accommodate approximately 52 kWh of energy, featuring a rapid heat discharge rate of 32.58 kW during the initial 30 min to effectively address sudden cooling demands. The overall heat discharge rate closely aligns with simulation results, reaching approximately 96% accuracy. This has been achieved through optimisation of the heat exchanger design through mathematical simulation, detailed testing to match various operational scenarios and evaluation of economic and peak load shifting benefits. The results demonstrate the environmental and economic effectiveness of the PCM thermal battery as an independent component in building cooling systems. It provides a timely response to peak cooling demand and improves thermal comfort of the buildings. [ABSTRACT FROM AUTHOR]

The applications for plug-in hybrid electric vehicles (PHEVs) and electrical vehicles (EVs) of Ni-rich NCA materials (LiNixCoyAlzO2, x + y + z = 1, x > 0.6) were restricted owing to the potential safety hazard and capacity attenuation during cycle. Herein, we reported a new application of Ni-rich LiNi0.8Co0.15Al0.05O2 in thermal battery with improved safety. At the current density of 100 mA cm−2 (10 C), the NCA cathode still showed a specific capacity as high as 541 mAh g−1 with a cut-off voltage of 1.2 V at 500 °C. Compared with the large current density discharge of lithium-ion batteries, the specific capacity of NCA at high-temperature excitation was far beyond the theoretical specific capacity (277 mAh g−1). It was mainly attributed to the special conversion reaction mechanism: 2 Li + Li2NiO2 → 2 Li2O + Ni. Such a high specific capacity is promising as a cathode material for thermal battery. [ABSTRACT FROM AUTHOR]

The main results of reports at the "Solar Energy" section were considered and summarized, in particular, one of the areas of solar energy - heat energy. In the work of the section in this direction, specialists from Ukraine and the Republic of Uzbekistan presented 10 reports. For the most part, the contents of the reports related to the directions of implementation of solar thermal energy technologies and the issues of effective use of solar radiation energy for obtaining thermal energy through the effective application of advanced technologies. [ABSTRACT FROM AUTHOR]

Cathode active materials and conductive additives for thermal batteries operating at high temperatures have attracted research interest, with a particular focus on compounds offering high thermal stability. Recently, FeF3 has been proposed as a candidate for high-voltage cathode materials; however, its commercialization is hindered by its low conductivity. In this study, conductive additives, such as Ni-coated carbon composites (multi-walled carbon nanotubes (MWCNTs) and carbon black (CB)), were utilized to enhance the thermal stability and conductivity of FeF3. The incorporation of metal–carbon conductive additives in the FeF3 composite increased the thermal stability by more than 10 wt.% and ensured high capacity upon conductivity enhancement. The FeF3@Ni/MWCB 15 wt.% composite containing 30 wt.% Ni exhibited a discharge capacity of ∼86% of the theoretical capacity of 712 mAh/g. The use of Ni-coated carbon-based conductive additives will allow the application of FeF3 as an effective high-temperature cathode material for thermal batteries. [ABSTRACT FROM AUTHOR]

CoS2 can meet the strict requirements of high probability output capacity and high energy output capacity of thermal batteries in modern weaponry thanks to its advantages of low resistivity and high thermal decomposition temperature combined with a full Li+ conductive electrolyte. Nevertheless, CoS2 has the limitations of a low voltage platform and theorical capacity. In this case, Fe and Ni are doped into the CoS2 lattice through low-temperature solid-phase sintering to synthesize Fe0.1Co0.8Ni0.1S2 with a single-phase structure. Fe0.1Co0.8Ni0.1S2 generated by the solid phase method has higher thermal stability, which can reduce the high temperature thermal shock at the immediate start of the thermal battery and assure the safety of the thermal battery in operation. Meanwhile, the mass loss of Fe0.1Co0.8Ni0.1S2 at 615 °C is only 5 %, allowing it to discharge at the maximum effective mass at the normal operating temperature(∼500 °C). Because of the synergistic action of Fe2+, Ni2+, and Co2+ in the discharge process, the discharge voltage of CoS2 increases significantly, giving CoS2 higher specific energy. The simultaneous boost in specific energy and specific capacity indicates that doping has been highly successful in modifying CoS2, making CoS2 more appropriate for the use of high current and long-life thermal cell systems.

Considerable research is being conducted on the use of FeF3 as a cathode replacement for FeS2 in thermal batteries. However, FeF3 alone is inefficient as a cathode active material because of its low electrical conductivity due to its wide bandgap (5.96 eV). Herein, acetylene black and multi-walled carbon nanotubes (MWCNTs) were combined with FeF3, and the ratio was optimized. When acetylene black and MWCNTs were added separately to FeF3, the electrical conductivity increased, but the mechanical strength decreased. When acetylene black and MWCNTs were both added to FeF3, the FeF3/M1AB4 sample (with 1 wt.% MWCNTs and 4% AB) afforded a discharge capacity of approximately 74% of the theoretical capacity (712 mAh/g) of FeF3. Considering the electrical conductivity and mechanical strength, this composition was confirmed to be the most suitable. [ABSTRACT FROM AUTHOR]

Nickel chloride (NiCi2), as a cathode material of high potential thermal battery, its poor conductivity limits Is application in thermal battery. In this study, cuprous ion doped nickel chloride (NiCl2-Cu.r) was prepared vasa liquid-phase mixing and low temperature calcination process. NiCl2-Cu5 possesses the best electro- chemical performance. Compared wk. NiCl2, NiCl2-Cu5 exhibits the advantages of high voltage and high specie- c energy. Especially at the current dimity of 500 cm2, NiCl2-Cu5 shows a high specific energy of 724 kg, which Ls about 82% higher than that of NiCl2. Pulse test shows that NiCl2-Cu5 cathode material has lower internal resistance and can aureate ohm polarization doing discharge, thus realizing high specific energy output. This work provides a new approach for the development of high-performance cathode materials for thermal battery. [ABSTRACT FROM AUTHOR]

This paper investigates the thermal battery as a research topic. We conducted an in-depth analysis of various thermal battery aspects, such as the cathode material CoS2 and electrolyte material morphology, crystal type, and interface state changes before and after service. The aim was to explore the core reaction and main failure mechanisms of the thermal battery. Prior to the reaction, the thermal battery cathode and electrolyte material consisted of pure-phase CoS2 and a composition of MgO-LiF/LiBr/LiCl. After service, the cathode and electrolyte of the single thermal battery exhibited significant morphological alterations caused by the presence of a molten state. The cathode transformed from CoS2 to Co3S4 and Co9S8 together with the presence of a marginal quantity of Co monomers visible throughout the discharge process, which was confirmed by means of XRD and XPS analyses. After the reaction, the electrolyte material was primarily made up of LiF, LiBr, and LiCl while the crystal components remained largely unaltered, albeit with apparent morphological variations. As was deduced from the thermodynamic analysis, the cathode material’s decomposition temperature stood at 655 °C, exceeding the working temperature of the thermal battery (500 °C) by a considerable margin, which is indicative of outstanding thermal durability within the thermal battery’s operational temperature range. Furthermore, the discharge reaction of the positive electrode was incomplete, resulting in reduced CoS2 residue in the thermal battery monomer after service. The reaction yielded a combination of Co3S4, Co9S8, and small amounts of Co monomers, indicating possible inconsistencies in the phase composition of the pole piece during the reaction process. In this study, we examine the distribution of residual stress in the thermal battery under various operating conditions. The simulation results indicate that exposure to a 70 °C environment for 2 h causes the maximum residual stress of the battery, which had an initial temperature of 25 °C, to reach 0.26 GPa. The thermal battery subjected to an initial temperature of 25 °C exhibited a maximum residual stress of 0.42 GPa subsequent to a 2-hour exposure to a temperature of −50 °C.

Evacuated tube heat pipe solar collector as a passive solar water heating system is a simple, reliable, and cost-effective way to capture the sun's thermal energy to supply hot water to homes. In the proposed system, the manifold is reshaped to a tank and filled with phase change materials (PCM) and porous media, which the PCM acts as a latent heat thermal energy storage medium. In order to increase the heat flux from the heat pipe to the PCM and overcome the low thermal conductivity of the PCM, porous media is used. The porous media is connected to the heat pipe condenser to collect the heat and distribute it uniformly throughout the PCM filling the pores. This design of the manifold acts as a heat storage tank or thermal battery. Another pipe in the tank transfers heat from the PCM to the water. Experiments were conducted in 2 modes: charging/discharging and periodic draw-off. The results demonstrated that this thermal battery design could provide homes with the hot water they require on sunny days, while it needs an auxiliary heater or larger solar collector to provide enough hot water on rainy/cloudy days. Considering the solar radiation fluctuation, the efficiency of the thermal battery is 50% ± 9.3%. The thermal battery can warm up the cold water higher than the operating temperature on a sunny day (more than 120 L per day at 38 °C). Using porous media provides better heat distribution in the PCM. [ABSTRACT FROM AUTHOR]

Current thermal simulation methods are not suitable for small-size fast-activation thermal batteries, so this paper provides an improved simulation method to calculate thermal cell temperature changes using the COMSOL platform. A two-dimensional axisymmetric model of thermal batteries has been established, considering the actual heat release situation and the mobile heat source of thermal batteries. Based on it, the temperature change and electrolyte melting of thermal batteries under high-temperature conditions (50 °C) have been simulated, in which the temperature change law, thermal characteristics, and electrolyte melting characteristics have been analyzed in depth. The results show that the additional heating flakes and insulation design above and below the stack can effectively reduce heat loss. Most of the melting heat of the electrolyte flows in from the negative side. In addition, the thermal battery activation time has been calculated to be 91.2 ms at the moment when all the thermal battery electrolyte sheets begin to melt, and the absolute error was within 10% compared with the experimental results, indicating that the simulation model has high accuracy and can effectively broaden the simulation area of thermal batteries. [ABSTRACT FROM AUTHOR]

This research evaluates the performance of a Phase Change Material (PCM) battery integrated into the climate system of a new transparent meeting center. The main research questions are: a. "Can the performance of the battery be calculated?" and b. "Can the battery reduce the heating and cooling energy demand in a significant way?" The first question is answered in this document. In order to be able to answer the second question, especially the way the heat loading in winter should be improved, then more research is necessary. In addition to the thermal battery, which consists of Phase Change Material plates, the climate system has a cross-flow heat exchanger and a heat pump. The battery should play a central role in closing the thermal balance of the lightweight building, which can be loaded with hot return or cold outdoor air. The temperature of the battery plates is monitored by multi-sensors and simulated by the use of PHOENICS (Computational Fluid Dynamics) and MATLAB. This paper reports reasonable agreement between the numerical predictions and the measurements, with a maximum variance of 10%. The current coefficient of performance for heating and cooling is already high, more than 27. There is scope for increasing this much further by making use of the very low-pressure difference of the battery (below 25 Pascal), low pressure fans and the ventilation system as a whole. [ABSTRACT FROM AUTHOR]

Fluoride ion battery was expected to become a new generation of energy storage system because of its high theoretical energy density. However, at room temperature, the ratio property of fluoride ion batteries was poor. Consequently, we conducted an investigation into the potential application of this technology in high-temperature primary discharge. A novel thermal battery based on fluoride ion conduction was reported, which can discharge with a large current at high temperature. Assemblying NiF 2 |NaF-KF-CsF@MgO|La thermal battery, the ionic conductivity of NaF-KF-CsF electrolyte run up to 2.47 × 10–1 S cm-1 at 550 °C. The battery has much higher ratio property than reported fluoride ion battery systems and the specific capacity can reach 60 mAh g-1(@1.35 V, 200 mA cm-2). Although the results are promising, they are not yet sufficient to meet the practical application scenarios of thermal batteries. Hence, this was a preliminary attempt to apply fluorine ion conduction to the field of thermal battery. [ABSTRACT FROM AUTHOR]

Thermal battery is a disposable reserve power source, which is of good research value in energy storage and other fields. In order to realize the efficient use of energy, there is an increasing demand to explore new and improved high-performance thermal batteries. The cathode materials, a key component of thermal batteries, have an essential impact on determining the electrochemical performance of these batteries. So far, the investigation based on cathode materials for thermal batteries has made great progress, and a series of new cathode materials have been developed. Herein, the latest research progress of cathode materials, including metal sulfide, metal halide and oxide cathode materials are reviewed. The material properties of various cathode materials and discharge performance are analyzed. Also, the modification methods such as structural nanosizing, surface modification, multifunctional composites, thin-film cathode materials, and hierarchical structural design are discussed and summarized in a multifaceted manner. Finally, the future development direction of cathode materials is envisioned. This review may contribute to an overall understanding of cathode materials and provide direction for in-depth study on high-performance thermal batteries. [Display omitted] • The development of cathode materials is summarized and presented. • Specific modification approaches for cathode materials are summarized. • The challenges and future development direction are outlined. [ABSTRACT FROM AUTHOR]

An elastocaloric thermal battery based on generative learning-designed phase-change alloys is developed to facilitate the efficient recycling of low-temperature waste heat. This battery stores thermal energy as latent heat in a phase-change alloy and releases it on demand through applied stress at ambient temperature. Alloy compositions and corresponding processing parameters, tailored to desired transformation characteristics, are efficiently discovered through a generative learning-enabled inverse design framework, which converts the hand-drawn target heat flow curve into tangible compositional and processing designs. The designed battery achieves an ultrahigh figure of merit for heat storage capacity, surpassing existing thermal batteries, and boasts a work-to-heat efficiency exceeding 9. This opens up exciting possibilities for manipulating thermal energy in diverse applications such as low-temperature waste heat recycling, solar thermal collection, and heat management in electric vehicles and data center facilities. The inverse design framework promises to expedite the development of various materials with tailored property curves., (© 2025 Wiley‐VCH GmbH.)

Thermal battery is an ideal power supply for military applications such as artillery and ship equipment. Due to the sheet-type process of the thermal battery, various installation error defects occur in the assembly of thermal battery. Aiming at the problems of low efficiency and low defect-recognition rate of thermal battery detection, a thermal battery defect detection model is proposed based on residual network. First, the squeeze-and-excitation networks (SENet) structure based on the attention mechanism is introduced into residual block of the residual neural network, the connection between the feature extraction channels is established, and the improved deep residual network I-ResNet50 is obtained; Second, in order to prevent overfitting, the defect images processed in the production line and the laboratory are data-enhanced and labeled. Transfer learning strategy is introduced into the recognition model I-ResNet50, and then the training set data samples are input into the recognition model I-ResNet50 for training, and the activation function LReLu and Dropout skills are introduced to improve the classification ability of the I-ResNet50 model; Finally, the recognition model I-ResNet50 is applied to the test set and validation set, and each defect of the thermal battery are output. Comparison experiments are tested under different migration strategies and different optimizers and learning rates, and comparison experiments with the five classic network structures of ResNet50, YOLOV3, MobileNetV2, VGG16, and YOLOV4 are also tested. The test data show that the recognition accuracy rates of qualified images and the three types of defective images (Qualified Assembly, Missing Current Plate, Wrong Number of Stacks, and Reverse Stack) can reach 99.64%, 98.17%, 99.11%, and 95.40%, respectively, the overall recognition accuracy rate can reach 98.10%. The test results illustrate the model can detect thermal battery defects more accurately and quickly, and has good defect diagnosis ability, which is nearly 5% higher than the traditional method, and a new solution for defect detection in practical industrial scenarios of thermal battery is provided.

The intermittency of solar energy has resulted in a urge to implement a buffer for providing constant and reliable energy in different sectors. Latent thermal energy storage solutions that use phase change materials have been the main focus of researchers due to their size, cost and near-constant operating temperatures. One of the main ways of performance improvement in concentric LTES units is changing the location of inner tube to introduce eccentricity and decrease the response and charging time of the unit. In this study, the eccentricity is implemented for different inner tube geometries, circle, square and triangle. The time dependent melting behavior of all the cases are presented by investigating the velocity, temperature and liquid fraction contours. The melting time is improved for all the cases with the triangle eccentric design having the lowest melting time. The charge time in the triangular case is decreased nearly 50% while the decrease is less significant for the circle and square designs. The natural convection improvement due to employment of eccentricity is the reason for the enhancements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Concentration gradient is constructed through pre-discharge state at small current for the single cell. • Construction of concentration gradient could decrease total resistance of LLZTO-based battery. • Higher specific energy is achieved for solid electrolyte-based thermal battery. • A method to constrcuct concentration gradient threading thermal field and elecric field. Ta-doped Li 7 La 3 Zr 2 O 12 (LLZTO) electrolytes not only show considerable potentials in solid-state Li metal batteries, but also display great possibility in thermal battery working at elevated temperature with high security. However, the great resistance of the single cell has hindered its practical application for the large interfacial resistance and high Li+ transport pressure. Herein, a new effective approach to construct intense interface and distinct concentration gradient of O2– and Cl- through pre-discharge state at small current (PDS) was successfully employed to decline the resistance of the LLZTO-based thermal battery under thermal and electric field. The formed intense interface is conductive under the thermal field than the pristine poor contact at the interface. The obtained significant and distinct concentration gradient of O2– and Cl- under the joint function of thermal and electric field achieves larger effective charge transport after PDS, suggesting lower polarization and resistance of the single cell owing to the relaxing burden of Li+. Consequently, the resistance of the single cell decreases to 2.4 Ω from 3.7 Ω, coming with larger specific energy at 500 °C (from 444 Wh kg−1 to 1038 Wh kg−1). This work provides a facile strategy to decline the resistance of the battery through the construction of concentration gradient, which is also promising to be used for battery whose materials are sensitive to electric or thermal field. [ABSTRACT FROM AUTHOR]

• Thermal battery resilience under high-impact conditions was assessed to sustain continual power supply for electronic devices equipped with artillery projectiles. • Honeycomb buffering devices with different wall thicknesses were adopted to compare their energy-absorption capacities. • Large-scale gas-gun tests and finite element simulations comparing buffering devices revealed distinct deformation patterns influencing impact deceleration. • The thermal battery retrieved from the gas-gun test proved to have reliable impact resilience for the target performance. Modern warfare relies heavily on electronic equipment, necessitating reliable energy sources like thermal batteries. Assessing their impact resilience, a study employed honeycomb-structured Al plates as buffering devices in a large-scale gas gun simulating artillery fire. Comparison between peak curves from gas-gun tests and simulations with varying honeycomb wall thicknesses revealed unique patterns, attributed to the buffering device's deformation-restoration process. Different honeycomb wall thicknesses led to varying deformation behavior and impact deceleration, complicating effective energy absorption assessment. Stepped honeycomb wall designs aimed to balance compression, extending energy absorption and reducing deceleration peaks. Prototype honeycomb buffering devices showed improved energy absorption and reduced deceleration during gas-gun tests. Gas-gun tests highlighted complexities in energy absorption assessment, with designs proposing improved energy absorption and reduced deceleration. The actual gas-gun test launched a projectile equipped with a thermal battery and buffering device, resulting in slight casing deformation, while battery cells remained intact, exceeding the standard discharge time (1 h). [Display omitted] [ABSTRACT FROM AUTHOR]

The accurate prediction of behavior for insulations within thermal battery can be impeded due to the fact that the thermal properties of insulations have not been thoroughly characterized under the complex conditions in which they operate. In this study, an effective and extendible model is developed based on fractal theory and finite element method to predict the flow and thermal properties for fibrous insulations within thermal batteries. Two common fibrous insulations are tested and verified with this model under the operating gas atmosphere of thermal battery. It is found that the predictive permeability and effective thermal conductivity agree well with the existing experimental data. Verification under various gas atmosphere shows that present model can reduce the relative error of existing model by 5.21–17.2 %. The gas contributed thermal conductivity for insulations filled with high thermal conductivity gas is always significant. In addition, under the tested pressure gradients, the deviations of temperature are generally greater than 1.42 % for air, methane and carbon dioxide atmosphere, but less than 0.7 % for hydrogen atmosphere. The high porosity of material, the large or reverse pressure gradient may strongly promote the influence of the energy migration within insulations. • A new predictive model is developed for insulation of thermal batteries. • The thermal properties is quantitative analyzed under complex conditions. • The relative error can be reduced by 5.21–17.2 % compared to existing models. • The energy migration should be considered for the applications of thermal batteries. [ABSTRACT FROM AUTHOR]

CoS 2 with high thermal stability is commonly used as cathode material for thermal batteries, however, its practical performance is limited by insufficient electrochemical reactions during discharge. Enlighted by metal-doping that can regulate the electronic environment and lattice structure, high-energy Co 0.8 Fe 0.2 S 2 is successfully prepared by solid-state methods. Remarkably, with a current density of 0.3 A·cm−2 at a cutoff voltage of 1.42 V under 550 °C, Co 0.8 Fe 0.2 S 2 exhibits excellent performance with a prolonged discharge platform and decreased resistance (0.23 Ω), generating an ultrahigh specific capacity of 652 mAh·g−1 , which is 31 % higher than that of pure CoS 2. Our research indicates that Co 0.8 Fe 0.2 S 2 is suitable for high-energy and high-temperature thermal batteries. The feasibility of solid-state synthesis of pure-phase bimetallic disulfides has been verified as well, paving the way for industrial application of Co 0.8 Fe 0.2 S 2. [ABSTRACT FROM AUTHOR]

Thermal batteries (TBs) are ideal power sources for high temperature environment due to their high specific energy, long storage time, and quick activation. However, the common molten salt electrolytes (MSE) suffer from overflow under overload or high spin state, which could lead to short circuit of the batteries. To address this issue, LiLaZrMO (LLZMO, M = Ga/Al) doped with different elements are prepared. The doping elements result in the phase change of LiLaZrO (LLZO) from tetragonal to cubic, alters the distribution of Li atoms and increases the ion transport bottleneck sizes. In particular, LiLaZrGaO (LLZGO) has the lowest activation energy (0.3 eV) and the highest total conductivity (2.57 × 10−2 S cm−1 at 500 °C) owing to the larger bottleneck and unique Li+ transport channel. TB with LLZGO provides the highest discharge specific capacity of 368.5 mAh g−1 and lowest internal resistance (0.23 Ω cm−2). Compared with the ones using LiF–LiCl–LiBr MSE, TB with LLZGO solid electrolyte (SE) also shows superior performance in pulse discharge capabilities due to the stable internal resistance as well as the fluctuation free characteristics. Therefore, LLZGO SE holds great potential as viable alternative to MSEs in TBs. • The LLZMO (M = Ga/Al) SE is used for the first time in the field of FeS 2 +CoS 2 /LiSi TB. • LLZMO SE has good thermal stability to solve the safety problem of MSE overflow. • Doping Ga in LLZO SE can optimize the transport path and bottleneck size of Li+. [ABSTRACT FROM AUTHOR]

For a solution to the problem that the wires of thermal batteries are prone to corrosion, A 1/Cu/Al composite tape, regarded as new wire, was prepared by means of cold rolling. The effect of heat treatment process on the growth rate of intermetallic compounds at the interface of Al and Cu and the conductivity of composite tape were investigated using SEM, XRT) and EDS. The results indicate that the Al/Cu/Al composite tape has better corrosion resistance and conductivity than pure Ni tape which is widely used at present. Distinctive inter-diffusion occured at elevated temperature in the composite tape and the relationship between holding time and the square of the thickness of diffusion layer in CuZ A1 belt is linear. The interface migration process is dominated by atom diffusion. The phases of diffusion layer in composite tape are Cu-Cur)Al--Cus Al2-Cu Al-CuAU-A1, and the existence of such intermetallic compounds results in the low conductivity of the composite tape. The conductivity of the composite tape reduces with the increasing of diffusion layer thickness, which manifested in three stages, the rapid reduction area (<25/jtm>), the slow reduction area (25 -35/im) and the accelerated reduction area (〉35/.tm). This phenomenon are attributed to the total content of compound phase in the interface of composite tape and the relative variation in the content of Cu AU and Curj Al-j. [ABSTRACT FROM AUTHOR]