Specific Energy Storage Research Articles

Lithium Doping Enhances the Aqueous Zinc Ion Storage Performance of V3O7 ⋅ H2O Nanorods

AbstractAqueous zinc‐ion batteries (AZIBs) offer significant advantages, including high safety, environmental protection and abundant zinc sources. V‐based layer‐like oxides are promising candidates as cathode materials for ZIBs; however, they face challenges such as low electrical conductivity, poor cycling stability, and limited Zn2+ storage capacity. In this study, Li‐V3O7 ⋅ H2O electrode materials were successfully synthesized using a hydrothermal method. The doping of lithium ions has led to a significant expansion of the interlayer spacing within the electrode structure, which enhances ion mobility and improves ion transport speed as well as charge‐discharge rates. Additionally, the increased spacing allows for the accommodation of more zinc ions, resulting in greater specific capacity and energy storage. More importantly, this modification reduces structural strain, minimizes the dissolution of vanadium‐based materials, and maintains electrode integrity over multiple cycles, thereby improving cycling stability. Consequently, the properties of V3O7 ⋅ H2O electrodes were substantially enhanced through lithium‐ion doping. The Li‐V3O7 ⋅ H2O cathode has a specific capacity of 411.8 mAh g−1 at low current and maintains 83 % of its capacity at 4.0 A g−1 for 4800 cycles, indicating a noteworthy improvement over pristine V3O7 ⋅ H2O. Exhibiting outstanding conductivity, discharge capacity, and cycling stability, it holds immense promise for future high‐performance energy storage.

Utilization of Tea Polyphenols as Color Developers in Reversible Thermochromic Dyes for Thermosensitive Color Change and Enhanced Functionality of Polyester Fabrics

Thermochromic textiles possess the capability to indicate ambient temperature through color changes, enabling real-time temperature monitoring and providing temperature warnings for body heat management. In this study, three thermochromic dyes—blue, red, and yellow—were synthesized using crystalline violet lactone (CVL), 6′-(diethylamino)-1′,3′-dimethyl-fluoran (DDF), and 3′,6′-dimethoxyfluoran (DOF) as leuco dyes, respectively, with biomass tea polyphenol serving as the color developer and tetradecanol as the phase change material. The chemical structures of these dyes were characterized using UV spectroscopy, infrared spectroscopy, Raman spectroscopy and 1H NMR. The thermochromic mechanisms were investigated, revealing that the binding bonds between the leuco dyes and the color developer broke and reorganized with temperature changes, imparting reversible thermochromic property. Polyester fabrics were dyed using an impregnation method to produce three reversible thermochromic fabrics in blue, red, and yellow. The structure and properties of these fabrics were analyzed, showing a significant increase in the UPF value from 26.3 to approximately 100, indicating enhanced UV resistance. Water contact angle measurements revealed that the contact angle of undyed polyester fabrics was 139°, while that of dyed polyester fabrics decreased by about 40°, indicating improved hydrophilicity. Additionally, the fabric inductive static tester showed that the static voltage half-life of dyed polyester fabric was less than 1 s, demonstrating a significant antistatic effect. Infrared thermal imaging results indicated that during the warming and cooling process, the thermochromic polyester fabric exhibited specific energy storage and insulation effects at 38 °C, close to the human body temperature. This study presented a novel approach to developing smart color-changing textiles using biomass-derived thermochromic dyes, offering diverse materials for personal thermal management, and intelligent insulation applications.

Chemistry and Physics of Wet Foam Stability for Porous Ceramics: A Review

The unique structural properties of porous ceramics, such as low thermal conductivity, high surface area, controlled permeability, and low density, make this material valuable for a wide range of applications. Its uses include insulation, catalyst carriers, filters, bio-scaffolds for tissue engineering, and composite manufacturing. However, existing processing methods for porous ceramics, namely replica techniques and sacrificial templates, are complex, release harmful gases, have limited microstructure control, and are expensive. In contrast, the direct foaming method offers a simple and cost-effective approach. By modifying the surface chemistry of ceramic particles in a colloidal suspension, the hydrophilic particles are transformed into hydrophobic ones using surfactants. This method produces porous ceramics with interconnected pores, creating a hierarchical structure that is suitable for applications like nano-filters. This review emphasizes the importance of interconnected porosity in developing advanced ceramic materials with tailored properties for various applications. Interconnected pores play a vital role in facilitating mass transport, improving mechanical properties, and enabling fluid or gas infiltration. This level of porosity control allows for the customization of ceramic materials for specific purposes, including filtration, catalysis, energy storage, and biomaterials.

Novel Wide-Working-Temperature NaNO3-KNO3-Na2SO4 Molten Salt for Solar Thermal Energy Storage.

A novel ternary eutectic salt, NaNO3-KNO3-Na2SO4 (TMS), was designed and prepared for thermal energy storage (TES) to address the issues of the narrow temperature range and low specific heat of solar salt molten salt. The thermo-physical properties of TMS-2, such as melting point, decomposition temperature, fusion enthalpy, density, viscosity, specific heat capacity and volumetric thermal energy storage capacity (ETES), were determined. Furthermore, a comparison of the thermo-physical properties between commercial solar salt and TMS-2 was carried out. TMS-2 had a melting point 6.5 °C lower and a decomposition temperature 38.93 °C higher than those of solar salt. The use temperature range of TMS molten salt was 45.43 °C larger than that of solar salt, which had been widened about 13.17%. Within the testing temperature range, the average specific heat capacity of TMS-2 (1.69 J·K-1·g-1) was 9.03% higher than that of solar salt (1.55 J·K-1·g-1). TMS-2 also showed higher density, slightly higher viscosity and higher ETES. XRD, FTIR and Raman spectra SEM showed that the composition and structure of the synthesized new molten salt were different, which explained the specific heat capacity increasing. Molecular dynamic (MD) simulation was performed to explore the different macroscopic properties of solar salt and TMS at the molecular level. The MD simulation results suggested that cation-cation and cation-anion interactions became weaker as the temperature increased and the randomness of molecular motion increased, which revealed that the interaction between the cation cluster and anion cluster became loose. The stronger interaction between Na-SO4 cation-anion clusters indicated that TMS-2 molten salt had a higher specific heat capacity than solar salt. The result of the thermal stability analysis indicated that the weight losses of solar salt and TMS-2 at 550 °C were only 27% and 53%, respectively. Both the simulation and experimental study indicated that TMS-2 is a promising candidate fluid for solar power generation systems.

Subsidy Policies and Economic Analysis of Photovoltaic Energy Storage Integration in China

In the context of China’s new power system, various regions have implemented policies mandating the integration of new energy sources with energy storage, while also introducing subsidies to alleviate project cost pressures. Currently, there is a lack of subsidy analysis for photovoltaic energy storage integration projects. In order to systematically assess the economic viability of photovoltaic energy storage integration projects after considering energy storage subsidies, this paper reviews relevant policies in the Chinese photovoltaic energy storage market. It analyzes the cost and revenue composition of photovoltaic energy storage integration projects, and constructs a system dynamics model for the levelized cost of electricity (LCOE) of such projects. Taking a specific photovoltaic energy storage project as an example, this paper measures the levelized cost of electricity and the investment return rate under different energy storage scenarios. Combining energy storage allocation ratios and internal rate of return indicators, this paper analyzes the net present value of photovoltaic energy storage integration projects under different subsidy standards. The results indicate that, while the current energy storage subsidy policies positively stimulate photovoltaic energy storage integration projects, they exhibit a limited capacity to cover energy storage investment costs, thereby failing to incentivize capital market participation in the construction of such projects. Rational allocation of energy storage capacity and optimization of corresponding subsidy policies are crucial prerequisites for enhancing the economic viability and widespread adoption of photovoltaic energy storage integration projects. This study not only aids in investment decision making for photovoltaic power stations but also contributes to the formulation of energy storage subsidy policies.

Electron-interactive 1D porous vertical NiCo2O4 nanowire and 3D N-doped graphene aerogel enable high hydroxyl-ion adsorption capacity for superior energy storage

Supercapacitors are a kind of highly efficient energy-storage device with long cycle life and high power density, however, their specific capacitance is insufficient for further application and development. In this work, a novel composite with one-dimensional (1D) NiCo2O4 nanowire arrays (NiCo2O4-NWA) vertically supported on three-dimensional (3D) nitrogen-doped graphene aerogel (NGA) is designed and facilely realized by hydrothermal reaction and thermal treatment. The NiCo2O4 nanowires, with length of ∼1 μm and diameter of ∼25 nm, display a porous structure and are regularly arranged on both sides of the sheets in nitrogen-doped graphene aerogel. The aerogel-supporting NiCo2O4 nanowires demonstrate a remarkably high specific capacitance of 2742 F g−1 at 1 A g−1, and an outstanding cyclic stability with capacitance retention of 90% even after 10,000 cycles at 80 A g−1. The density functional theory calculation shows the narrow band gap (0.32 eV) and strong electronic interaction and hydroxyl-ion adsorption effect of NiCo2O4 supported on NGA, resulting in superior specific capacitance and energy storage performance. The 3D nitrogen-doped graphene aerogel supporting 1D nanowire arrays represent a promising high-performance electrode material for application in the supercapacitors and other electrochemical energy-conversion and storage equipment.

Numerical simulation of a combined thermochemical-latent energy storage system based on paired metal hydrides and phase change material

The main goal of this paper is to assess the operating performance of a thermal energy storage system that combines latent and thermochemical heat storage for their utilization in industrial waste heat recovery as well as in solar power plants. Thermal energy is stored and released through endothermic desorption and exothermic absorption processes, thereby cycling hydrogen between two paired metal hydrides (MHs). The thermal performance of the dynamically coupled Mg2Fe/LaNi5 pair, which has never been investigated before, is presented in this study. Sodium acetate trihydrate is used as a PCM for the LaNi5-tank thermal management. Moreover, during the heat charging stage, the Mg2Fe-tank was subjected to a typical solar heat flux. A mathematical model has been established and utilized to simulate how the storage system would operate in practical situations. The impacts of the operating conditions, which are the efficiency of the supplied heat system, the HTF temperature, the heat transfer coefficient, and the initial temperature of the MH beds, on the storage system's performance are studied and discussed in detail. The findings from this investigation revealed that the pairing of Mg2Fe with LaNi5 at suitable operating conditions enabled the storage system to achieve a specific energy storage capacity of 2 MJ/kg of Mg2Fe and an efficiency of 87.1 %. The results of this study reveal the excellent performance of a potential and viable metal hydride pair (Mg2Fe/LaNi5) for its usage in thermal energy storage systems.

Ionic liquid interlayer enable room-temperature, high-voltage, high-specific-capacity solid-state lithium-metal batteries

Li7La3Zr2O12 (LLZO)-based solid-state lithium-metal batteries (SLBs) are strong candidates for next generation high specific capacity and high safety energy storage devices. Unfortunately, poor interfacial contact between the cathode and the solid-state electrolyte (SSE) severely limits the practical application of SLBs. Here, a pyrrole-based (1-Butyl-1-methyl pyrrolidinium Bis (trifluoromethanesulfonyl) imide) ionic liquid (BMP-IL) electrolyte interlayer is used to address this issue. The IL interlayer provides a fast Li+ transport channel at the SSE and cathode interface. As a result, SLBs exhibit excellent electrochemical performance at 25 °C. Further, the IL interlayer strategy combines with a high-voltage cathode to achieve higher energy density, and the batteries perform discharge specific capacities as high as 147 mA h g−1. At the same time, the SLBs also exhibit more pronounced capacity degradation, which is attributed to the interfacial side reactions at high voltages. This work demonstrates the robust feasibility of the IL interlayer strategy and provides insights into the degradation mechanisms at the interface when matched with a high-voltage cathode. It offers valuable insights into the practical applications of SLBs and lays the foundation for subsequent research on high-voltage SLBs.

Waste-derived thermal storage solutions for sustainable solar desalination using discarded engine oil and paraffin wax: A techno-environmental feasibility evaluation

The valorization and repurposing of waste materials for sustainable outcomes and environmental mitigation are gaining prominence. This investigation explores the feasibility of repurposing discarded automotive engine oil as a viable means of energy storage in solar thermal desalination applications. A novel approach combining discarded engine oil with Paraffin wax in equal parts by volume is proposed as a composite energy storage (CES) to enhance nocturnal production and efficiency. The experimental findings show that the composite energy storage system has 26.54 % higher thermal conductivity and 44.66 % greater specific heat energy storage capacity compared to pure paraffin wax. Comparing the Desalination System with Engine Oil-based Energy Storage (DSEES) to a Traditional Solar Desalination System (TSDS) without energy storage, considering water and absorber temperatures and distillate production, reveals compelling advantages. DSEES exhibits remarkable temperature increases of 14 % in the basin and 11 % in water, alongside a significant 52.72 % rise in distillate production rates, yielding 3.36 and 3.16 l/sq.mt compared to TSDS's 2.2 and 2.1 l/sq.mt over two testing days. Cost analysis indicates DSEES's 33.7 % lower cost per liter and 33.8 % shorter payback period relative to TSDS. Furthermore, environmental assessment highlights DSEES's 60.8 % greater net carbon credit, indicating reduced ecological impact.

Experimental investigation of a thermochemical energy storage system based on MgSO4-silica gel for building heating: adsorption/desorption performance testing and system optimization

To address the gap between the thermochemical energy storage (TCES) performance of MgSO4-porous matrix composites in small-scale prototypes and their practical application, a TCES system with an output power of 50 kW was designed and constructed to investigate the feasibility of using MgSO4-silica gel composites in large-scale storage systems for long-term heating applications. Thirty consecutive sets of experiments were performed on both the reactor and the system. Aiming at energy storage system for space heating and hot water supply, four parameters (energy consumption, energy storage density, energy storage efficiency, and specific energy storage capacity) were investigated as the key performance evaluation indicators. The experiment results indicated the energy consumption of the heater and humidifier account for approximately 80 % of total energy consumption. The findings also demonstrated the potential to increase the ESD from 0.47 GJ/m3 to 0.76 GJ/m3 by exploiting the heat generated from the additional circulation water in the reactor’s shell. The optimized system achieved an efficiency increase of ∼ 11 %, reaching over 60 %, and the specific energy storage capacity can reach up to 198.15 Wh/kg. In addition, the supply water temperature can stay above 50 °C for roughly 4 h, with a maximum value from 70.1 °C to 82.4 °C, and the water temperature lift was found to as high as 57.4 °C. Additionally, the adsorption heat accounted for approximately 44 % of the total energy storage.

Effect of Al2O3 nanoparticle dispersion on the thermal properties of a eutectic salt for solar power applications: Experimental and molecular simulation studies

Thermophysical properties of molten salts aid in determining the storage efficiency of thermal energy storage (TES) systems in concentrating solar power plants. In this research, a novel ternary molten salt (4NaCl–37KCl–59LiNO3, mol%) was utilized as the phase change material (PCM), while Al2O3 nanoparticles (NPs) were employed as a thermal conductivity enhancer. Experimental measurements and molecular dynamics simulations were conducted to confirm that the introduction of Al2O3 NPs as dopants enhanced the specific heat, thermal conductivity, and energy storage density of the eutectic salt. Specifically, at an Al2O3 NP content of 0.5 wt%, the composite PCM exhibited a 44.23 % increase in liquid-state specific heat and a 40.82 % increase in liquid-state thermal conductivity, along with a 15.73 % increase in storage density. This study demonstrates that the enhanced thermal properties of eutectic salts by adding Al2O3 NPs are primarily attributed to the emergence of nanostructures and alterations in atomic potential energy, as evidenced by both experimental and simulated microstructural analyses. These findings offer valuable insight into the selection of thermal storage materials and additives, as well as their implementation in medium-temperature TES systems, with the objective of optimizing the efficient utilization of solar energy.

Integrated Thermoelectric Energy Storage in A Combined Cycle Solar Power Plant (tour)

Multi megawatt-thermoelectric energy storage based on thermodynamic cycles is an ambitious solution for the renewable energies conversion. The main advantage of this technology is the capacity of energy storage, However, ensuring the operation of TEES stations during unfavorable weather conditions is suspended. In this article, a specific thermoelectric energy storage system was studied «TEES», the TEES system converts electrical energy into sensible heat by means of an electric heater that uses the joule heating effect, the system TEES converts sensible heat into electrical energy by means of a hybrid power plant that operates on a combined cycle « Brayton and Rankine ». The hybrid power plant uses two thermal energy sources In order to secure the station in unfavorable weather conditions for the production of solar energy. The main idea is to using the gaz and the sensible heat stored as two thermal inputs in the gas turbine that uses a Brayton cycle, the thermal rejection from the gas turbine was recovered and used as a thermal input in the conventional steam turbine plant that uses a Rankine cycle. A thermodynamic analysis of the TEES system was performed in steady state, using the thermodynamic properties of the Coolprop database, a maximum thermal efficiency or Round trip electrical efficiency of 50% has been reached; when the heating temperature of the compressed air reaches 1100 ° C and When the isentropic efficiency of steam turbine is 90 percent.

Graphene hydrogel modification with 4-methylumbelliferone molecules as electrode material for supercapacitor

Graphene hydrogels (GH), as a derivative of graphene have become a research hotspot in the field of energy storage due to their three-dimensional network structure which can prevent the agglomeration of graphene. The specific capacitance and energy storage ability can be further increased by non-covalent functional graphene hydrogels with organic small molecules. In this work, 4-methylumbelliferone (DTBF) molecules interacted on the surfaces of GH via π-π interactions to get a carbon electrode material (DTBF/GH) by one-step hydrothermal. On the one hand, the DTBF molecules can contribute capacitance by faradic reactions, on the other hand, they can act as spacers to hinder the accumulation of graphene nanosheets, thus enhancing the specific surface area of graphene and promoting the migration of electrolyte ions. As a result, DTBF/GH displays an ultrahigh-specific capacitance. The specific capacitance can reach up to 578 F g−1 (1 A g−1). To verify the influence of electrode material matching on capacitor performance, an asymmetric supercapacitor and a symmetrical capacitor are assembled respectively. Although the specific capacitance of the DTBF/GH material is higher than that of activated carbon (AC), the energy density (Ed = 19 Wh kg−1) of the DTBF/GH//AC capacitors is higher than that of the DTBF/GH//DTBF/GH capacitors. It shows that the matching of electrode materials has a great influence on the Ed and the power density (Pd) of the capacitor. In addition, two DTBF/GH//AC devices in series can light 47 LEDs.

Evaluating the Role of Integrated Photovoltaic and Energy Storage Systems in the Net-Zero Transition: A Case Study in Taiwan

This study investigates the role of integrated photovoltaic and energy storage systems in facilitating the net-zero transition for both governments and consumers. A bi-level planning model is proposed to address the challenges encountered by existing power supply systems in meeting the escalating electricity demands. In the upper level, governments provide incentives to users through subsidies for photovoltaic power generation, energy storage system installations, and electricity procurement. Meanwhile, at the lower level, load requirements are optimized, and costs are minimized by integrating solar power generation, battery energy storage, and electricity procurement. To effectively address these complexities, a hybrid physics-inspired algorithm for bi-level programming is utilized for iterative problem solving. The findings indicate that relying on photovoltaic output during peak load periods and conducting small electricity purchases, while storing excess electricity, proves to be an efficient approach. This model offers a cost-effective solution for managing energy consumption, mitigating potential power shortages, and reducing frequent outages. Furthermore, this research contributes to a comprehensive understanding of the net-zero transition and its implications for power supply systems. Specifically, it highlights the significance of integrated photovoltaic and energy storage systems in assisting businesses with specific energy storage planning, determining optimal charging and discharging schedules, and considering government subsidies.

Highly lithiophilic and structurally stable Cu–Zn alloy skeleton for high-performance Li-rich ternary anodes

Lithium (Li)-rich ternary alloy, comprising a multi-alloy phase as the built-in three-dimensional (3D) framework and a Li metal phase as a reversible Li reservoir, is a promising high-energy–density anode for rechargeable Li metal batteries. The introduction of metal/metalloid components to the alloy can effectively regulate Li deposition and maintain the dimensional integrity of the Li anode. Herein, the lithium–copper–zinc (Li–Cu–Zn) ternary alloy, as a new type of alloy anode, is synthesized via a facile thermal melting method. The fully delithiated 3D scaffold comprised two Cu–Zn alloy phases named CuZn and CuZn5. These alloy phases exhibit higher lithiophilicity and structural stability than Li–Zn and Li–Cu alloys. Moreover, the CuZn phase is electrochemically inert, ensuring the geometric stability of the anode, while the CuZn5 phase can readily undergo alloying reaction with Li to form the LiZn phase, thereby facilitating uniform Li nucleation and deposition. The hybridized multiphase alloy structure and specific energy storage mechanism of the Cu–Zn based alloy scaffold in the ternary alloy anode facilitate dendrite-free Li deposition and prolonged cycle lifetime. The Li metal full battery based on lithium iron phosphate (LiFePO4) cathode exhibits high cycling stability with high-capacity retention of 95.4% after 1000 cycles at 1C.

Investigation of Different Rotational Speed Characteristics of Multistage Axial Compressor in CAES System

An axial compressor has high efficiency under design conditions, but its stable working range is narrow. Adjusting the rotational speed can effectively expand the stable working range. In this paper, a five-stage axial compressor for a specific compressed air energy storage (CAES) system is taken as the research object, and different rotational speed (DRS) characteristics are studied with NUMECA software. Firstly, the influence of DRS on overall aerodynamic performance is explored, and the working flow range of the compressor is increased from 11.5% to 54.0%. Secondly, the effect of DRS on inlet parameters of the first stage rotor is analyzed, and the reasonable distribution of inlet parameters is obtained. Thirdly, the changing law of the internal flow is investigated at DRS. The corner separation is gradually enhanced when the rotational speed increases, and the leakage flow velocity at the rotor tip gradually improves. Finally, the loss distribution of tip clearance is researched. The result shows that the loss distribution increases significantly in both circumferential and spanwise directions when the speed increases. This work aims to provide a reference for the stable and efficient operation of axial compressors in CAES systems under the wide working range.

Biologically Assisted Construction of Advanced Electrode Materials for Electrochemical Energy Storage and Conversion

AbstractBio‐organisms with various architectures and versatile physiological functions provide a substantial bibliography for electrode design. To elucidate how bio‐organisms and bio‐schemes take effect in advanced electrode materials, this review sorts bio‐assisted construction into two categories, namely, biotemplating synthesis and biomimetic artificial fabrication. The former section summarizes unique characteristics of different biotemplates for electrode preparation, including “bottom‐up” structural designability of biomolecules, metabolism involving, and genetic alterable properties of biological cells, as well as, the structural regularity and integrity of bio‐tissues, with the aim to provide guidelines for manipulating bioarchitectures and endow biotemplating synthesis of electrodes with more designability. The later describes recent efforts in using bio‐prototypes to enhance the essential properties associated with advanced electrodes, including mechanical properties, wettability, mass transport, electron/charge transfer, and catalytic activity, with intensive concerns on the function principles of biomimetic designs in electrochemical systems. Then, advances in applications of bioderived and biomimetic electrode materials are summarized emphasizing how bio‐structures/components and bionic designs help to enhance the charging/discharging and electrocatalytic performance in specific electrochemical energy storage and conversion systems. Finally, future trends with prospects and challenges for developing new bioderived/biomimetic electrode materials, as well as, related conceptual innovation on bionics, are discussed in the last section.

In Situ Mineralization of Biomass‐Derived Hydrogels Boosts Capacitive Electrochemical Energy Storage in Free‐Standing 3D Carbon Aerogels

Here, a novel fabrication method for making free‐standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass‐derived hydrogels is presented. In situ formed flower‐like CaCO3 molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one‐step activation graphitization (iMAG), while the intrinsic structural integrity of the carbon aerogels was maintained. The homogenously distributed minerals simultaneously acted as a hard template, activating agent, and graphitization catalyst. The decomposition of the homogenously distributed CaCO3 during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical performance. At 0.5 mA cm−2, the gravimetric capacitance increased from 0.01 F g−1 without mineralization to 322 F g−1 with iMAG, which exceeds values reported for any other free‐standing or powder‐based biomass‐derived carbon electrodes. An outstanding cycling stability of ~104% after 1000 cycles in 1 M HClO4 was demonstrated. The assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g−1 and a high energy density of 26 W h kg−1 at a power density of 4000 W kg−1, with excellent cycling performance (98.5% retention after 2000 cycles). In combination with the proposed 3D printed mold‐assisted solution casting (3DMASC), iMAG allows for the generation of free‐standing carbon aerogel architectures with arbitrary shapes. Furthermore, the novel method introduces flexibility in constructing free‐standing carbon aerogels from any ionically cross‐linkable biopolymer while maintaining the ability to tailor the design, dimensions, and pore size distribution for specific energy storage applications.

Tremella-like Vanadium Tetrasulfide as a High-Performance Cathode Material for Rechargeable Aluminum Batteries

Rechargeable aluminum batteries (RABs) are gaining widespread attention for large-scale energy storage applications as a result of their high energy densities, high security, and abundance. The key to sustain the progress of RABs lies in the quest for the proper cathode materials with prominent capacity and reversible cycle life. Herein, we propose a tremella-like VS4 as a cathode material aiming to tackle this problem. Obtained from a morphology modification process, VS4 with a unique nanosheet structure provides sufficient active sites for intercalation and conversion reactions, shortens the transport paths for charge carrier ions, and facilitates the infiltration process for electrolyte. The RAB with the VS4 cathode exhibits excellent electrochemical performance, including outstanding specific capacity (407.9 mAh g-1) and stable cycling performance (∼300 cycles at a high current density). The energy storage mechanism has been comprehensively investigated and is confirmed to be a combination of the intercalation/deintercalation of Al3+ and AlCl4- ions and conversion reaction by various techniques and DFT calculation. Our study not only provides a peculiar and simple strategy for the rational design of metal sulfide cathode materials with high capacity and long-term stability but also proposes a specific energy storage mechanism that guides the development of cathode materials of RABs in the future.

Comprehensive performance of composite phase change materials based on ternary eutectic chloride with CuO nanoparticles for thermal energy storage systems

Herein, a novel phase change energy storage material based on a NaCl (15 wt%)-KCl (45 wt%)-LiCl (40 wt%) ternary molten salt and CuO nanoparticles with varying mass fraction as a heat transfer enhancer is produced through a combination of static melting and mechanical stirring methods. According to the microcosmic characterization data, a microphysical structure of a ternary chlorine salt, partially doped with CuO, is formed. According to the thermal analysis results, CuO nanoparticles are able to effectively improve specific heat, thermal conductivity and energy storage density of ternary chloride salts without any change in their melting point, freezing point and latent heat of fusion. In particular, the CuO nanoparticles with a 3% mass fraction are shown to be more appropriate as the enhanced heat transfer agents. The phase change materials produced in this study exhibit high heat transfer efficiency, high energy storage density and excellent high temperature cycling stability, which make them applicable in thermal energy storage systems.