High Storage Capacity Research Articles

Metallic wood-based phase change material with superior anisotropic thermal conductivity and energy storage capacity

In this study, metallic wood-based phase change material (MWM) with high performance anisotropic thermal conductivity and energy storage capacity was developed by impregnating wood with myristic acid, and subsequent introducing low melting point alloy (LMA) into the wood through a facile alternating high and low temperature heat treatment. The heat-driven LMA was rapidly squeezed into the cell lumens of the wood so as to effectively inhibit the leakage of the internal myristic acid during melting. Benefited with the well-aligned and hierarchical porous structure, the filled LMA formed a continuous heat transfer network along the highly oriented transport tissue of wood, which could greatly reduce the interfacial thermal resistance and promote heat transfer. Compared with untreated wood, the thermal conductivity of MWM in longitudinal and radial directions were improved by more than 67 % and 75 %, respectively. In addition, it exhibited superior energy storage capability, with the latent heat of 90.23 J/g and 86.42 J/g during melting and solidification. The thermal stability and anti-leakage performance were satisfied. The phase change temperatures, enthalpies and chemical structure of MWM remained unchanged after 100 thermal cycles, demonstrating outstanding cycling reliability. With excellent energy storage performance and favourable thermal conductivity, the prepared MWM shows a promising application in energy saving buildings and solid wood floors.

Metal-Hydroxide Organic Frameworks for Aqueous Nickel-Zinc Batteries.

Hydroxides exhibit a high theoretical capacity for energy storage by ion release and are often intercalated with anions to enhance the ion migration kinetics. In this study, a series of metal-hydroxide organic frameworks (MHOFs) are synthesized by intercalating aromatic organic linkers into hydroxides using I-M/Ni(OH)2 (where M = Co2+, Cu2+, Mg2+, Fe2+). The coordination environment and layer spacing (1.09 nm) of I-M/Ni(OH)2 are explored by X-ray absorption fine structure and cryo-electron microscopy. The intercalation nanostructure improves the conductivity of the hydroxides and facilitates Zn2+ migration by increasing the interlayer spacing, while enhancing the rate capability and cycling stability. Consequently, the I-Co/Ni(OH)2 material exhibites a satisfactory specific capacity of 0.35 mAh cm-2 at 3 mA cm-2 and a high peak power density of 6.78 mW cm-2. This study offers a novel perspective on the design of intercalated hydroxide and provides new insights into high-performance nickel-zinc batteres.

Magnetron Sputtering Formation of Germanium Nanoparticles for Electrochemical Lithium Intercalation.

In the drive towards increased lithium based battery capacity, germanium is an attractive material due to its very high lithium storage capacity, second only to silicon. The persistent down-side is the considerable embrittlement accompanying its remarkable volume expansion of close to 300 %. A proven method to accommodate for this lattice expansion is the reduction of the size towards the nanoscale at which the fracturing is prevented by "breathing". In this work we employed a novel magnetron sputtering gas aggregation nanoparticle generator to create unprecedented layers of well-defined germanium nanoparticles with sizes below 20 nm. The electrochemical lithium intercalation was monitored by a suite of techniques under which Raman spectroscopy, which provided clear evidence of the presence of lithium inside the germanium nanoparticles. Moreover, the degree of lattice order was measured and correlated to the initial phases of the lithium-germanium alloy. This was corroborated by electron diffraction and optical absorption spectroscopy, of which the latter provided a strong dielectric change upon lithium intercalation. This study of low lithium concentrations inside layers of well-defined and very small germanium nanoparticles, forms a new avenue towards significantly increasing the lithium battery capacity.

Electrochemical Performance of MoB/Si3N4 Heterojunction as a Potential Anode Material for Li Ion Batteries.

In response to the current policy of high storage capacity, two-dimensional (2D) materials have revealed promising prospects as high-performance electrode materials. MoB, as a type of such material, is widely regarded as an anode candidate for Li-ion batteries due to its large specific surface area and abundant ion diffusion channels; the long-term cycling stability, however, is poor owing to material pulverization during the cycle. Therefore, MoB/Si3N4 heterojunction in this work is proposed as an anode material, with Si3N4 acting as a skeleton, maintaining the stability of the structure, while retaining the high energy storage properties of MoB as well. In addition, a certain built-in electric field is formed between them, which can play a role in regulating charge transfer, improving the ion transport channel, and accelerating the migration rate. Herein, the structural, electronic, and electrochemical properties are systematically investigated by first-principles calculations; the final results indicate that the heterojunction anode material does indeed have built-in electric fields, which promote the anode material to possess excellent electrical conductivity and outstanding electrochemical property. Meanwhile, the introduction of vacancy defects can bolster the diffusion kinetic performance of ion transport and greatly reduce the diffusion energy barrier of Li ions, which is conducive to the realization of rapid charge and discharge for the Li ion battery. Based on the synergistic effect of two single-component materials, the synthesized anode material displays a high theoretical capacity of 461 mAh/g, and the calculated open-circuit voltage is 0.66 V, within the range of the negative electrode criterion of 0-1 V, which can effectively play a role in preventing the formation of Li dendrites; these properties are comparable to other 2D anode materials as well. Given these intriguing properties, the MoB/Si3N4 heterojunction is an exceptional candidate for advanced LIB high-performance anode materials.

1T′-MoSP monolayer as an anode material for sodium-ion batteries with ultrahigh storage capacity and ultralow diffusion barrier

Sodium-ion batteries (SIBs) have gained significant attention due to the abundant availability and low cost of sodium. However, the search for high-performance anode materials remains a critical challenge in advancing SIB technology. Based on first-principles swarm-intelligence structure calculations, we propose a metallic 1T′-MoSP monolayer as an anode material that offers a remarkably high storage capacity of 1011 mA h g−1, an ultralow barrier energy of 0.04 eV, and an optimal open-circuit voltage of 0.29 V, ensuring high rate performance and safety. Additionally, the monolayer presents favorable wettability with commonly used SIB electrolytes. Even after adsorbing three-layer Na atoms, the 1T′-MoSP monolayer retains its metallic nature, ensuring excellent electrical conductivity during the battery cycle. These desirable properties make the 1T′-MoSP monolayer a promising anode material for SIBs.

Estimation of Recovery Efficiency in High‐Temperature Aquifer Thermal Energy Storage Considering Buoyancy Flow

AbstractWith their high storage capacity and energy efficiency as well as the compatibilities with renewable energy sources, high‐temperature aquifer thermal energy storage (HT‐ATES) systems are frequently the target today in the design of temporally and spatially balanced and continuous energy supply systems. The inherent density‐driven buoyancy flow is of greater importance with HT‐ATES, which may lead to a lower thermal recovery efficiency than conventional low‐temperature ATES. In this study, the governing equations for HT‐ATES considering buoyancy flow are nondimensionalized, and four key dimensionless parameters regarding thermal recovery efficiency are determined. Then, using numerical simulations, recovery efficiency for a sweep of the key dimensionless parameters for multiple cycles and storage volumes is examined. Ranges of the key dimensionless parameters for the three displacement regimes, that is, a buoyancy‐dominated regime, a conduction‐dominated regime, and a transition regime, are identified. In the buoyancy‐dominated regime, recovery efficiency is mainly correlated to the ratio between the Rayleigh number and the Peclet number. In the conduction‐dominated regime, recovery efficiency is mainly correlated to the product of a material‐related parameter and the Peclet number. Multivariable regression functions are provided to estimate recovery efficiency using the dimensionless parameters. The recovery efficiency estimated by the regression function shows good agreement with the simulation results. Additionally, well screen designs for optimizing recovery efficiency at various degrees of intensity of buoyancy flow are investigated. The findings of this study can be used for a quick assessment and characterization of the potential HT‐ATES systems based on the geological and operational parameters.

Dual storage mechanism of Bi2O3/Co3O4/MWCNT composite as an anode for lithium-ion battery and lithium-ion capacitor

Bismuth oxide(Bi2O3) and cobalt oxide(Co3O4) are promising owing to their unique properties, high storage capacity, low cost, and eco-friendliness, making them ideal for lithium-ion batteries(LIBs) and lithium-ion capacitors(LICs) anodes. This study presents the synthesis and thorough characterization of Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT composites as potential LIB and LIC anode materials. The materials are synthesized using a hydrothermal process succeeded by annealing. Structural, morphological, and compositional studies were analyzed. Various tests evaluated electrochemical performance, including cyclic voltammetry(CV), confirming a dual storage mechanism like alloying and conversion reaction involved for better energy storage. Specific discharge capacities of 834 mAh/g and 1184 mAh/g were recorded for Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT composite electrodes at a current density of 100 mA/g, respectively. The composite material exhibited notably enhanced rate capability, with 31 % and 51 % discharge capacities for Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT, respectively. The cyclic stability assessment revealed that Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT maintained a high coulombic efficiency of around 99 % over 250 charge–discharge cycles at a high current density of 1 A/g. The capacity retention was approximately 253 mAh/g for Bi2O3/Co3O4 and 439 mAh/g for the Bi2O3/Co3O4/MWCNT composite, indicating excellent cyclic stability and minimal energy loss during cycling. Moreover, the LICs assembly of Bi2O3/Co3O4/MWCNT//CB was investigated, revealing a power density of 200 W kg−1 alongside an energy density of 8.64 Wh kg−1. The cyclic stability assessment over 10,000 cycles exhibits a capacity retention of approximately 45 % under a high current density of 2 A/g.

Exploring the Synergistic Potential: A Comprehensive Review of MXene-Based Composite Electrocatalysts

MXenes, a prominent category of 2D materials consisting of transition metal carbides, nitrides, and carbonitrides, have garnered significant interest since the introduction of Ti3C2Tx. This fascination arises from their exceptional attributes like their high special surface area, superb electrical conductivity, and remarkable mechanical strength. These qualities have established MXenes as top materials for electrocatalysis, a critical component of clean energy conversion technologies. Crucially, MXenes serve as the foundation for the next generation of electrocatalysts, aiming at high activity, selectivity, and sustainability.In electrocatalysis, MXene composites enhance the performance of various reactions, such as water splitting and fuel cell operations. When combined with metals, metal oxides, or other conductive materials, MXenes exhibit improved electrical conductivity and catalytic activity. These composites can achieve higher efficiency and selectivity in electrochemical reactions, making them suitable for sustainable energy applications. MXene composites also play an significant role in the development of supercapacitors, which are energy storage devices characterized by rapid charge and discharge capabilities. The high special surface area and excellent conductivity of MXenes increase charge storage and improve energy and power density. When MXene composites are mixed with materials such as polymers or other nanomaterials, they can further optimize these properties, leading to increased performance and longevity. Also in battery technology, MXene composites are used to improve the performance of anodes and cathodes. Their high capacity for ion storage and conduction contributes to higher energy density and faster charge/discharge rates. By combining MXenes with other materials, researchers are able to create advanced battery systems that overcome traditional limitations, resulting in batteries that are more efficient, durable, and capable of delivering higher performance. In this study MXene–Carbon composites, MXene-LDH composites, MXene-Polymer composites, MXene-MOF composites are reviewed and discussed. The versatility of MXenes is further enhanced when they are composited with various other materials. Such compositions allow for tailoring their innate properties, enabling a widespread range of applications. In terms of environmental implications, MXenes and their composites boast excellent reducibility, conductivity, and biocompatibility, making them very appropriate for use in environmental clean-up and protection applications.

Dual-Functional SnO2-CNT-PANI||PP||SnO2 Separator for Enhanced Lithium-Sulfur Battery Stability and Capacity

Lithium-sulfur batteries (LSBs) provide high capacity and energy density for advanced energy storage but encounter performance and safety issues due to lithium polysulfides (LiPSs) dissolution and dendrite formation. This study introduces a dual-functional SnO2-CNT-PANI||PP||SnO2 separator (DF-SNCPS) aimed at improving the stability and safety of LSBs. The separator includes a SnO2-CNT-PANI layer on the sulfur cathode side for enhanced electrical conductivity and polysulfide adsorption and a SnO2 nanoparticle (nano-SnO2) layer on the lithium anode side to regulate lithium-ion concentration and inhibit dendrite growth. Density functional theory (DFT) and the phase field method have verified the relevant material's catalytic performance and dendrite suppression ability. These methods have provided a comprehensive understanding of the underlying mechanisms, providing auxiliary explanations for their role in catalyzing polysulfide conversion and suppressing lithium dendrite growth. This innovative design mitigates the shuttle effect and enhances cyclic stability and sulfur utilization, achieving a notable cyclic performance with a capacity retention of 0.05% per cycle over 800 cycles at 1C. The synergistic effects of the modified separator present a viable pathway for LSB commercialization.

Achieving high capacity and ultra-stable sodium storage of Na2TiV(PO4)3 cathode by integrated lattice regulation and surface modification

Achieving high capacity and ultra-stable sodium storage of Na2TiV(PO4)3 cathode by integrated lattice regulation and surface modification

The role of hydrogen in the synthesis of High-entropy alloys and their hydrides

The aim of this work is to present the new technique processes of formation of stable hydrides of High-entropy alloys (HEAs) with high hydrogen content. The essence of the proposed method is the sequential use of self-propagating high-temperature synthesis (SHS) method for producing the metal hydrides, followed by the formation of alloys in the hydride cycle (HC) method. Preliminary, the hydrides of three compositions of metal mixtures were synthesized in SHS: 0.2TiH2+0.2ZrH2+0.2HfH2+0.2VH2+0.2NbH2, 0.3TiH2+0.15ZrH2+0.15HfH2+0.2VH2+0.2NbH2 and 0.3TiH2+0.1ZrH2+0.1HfH2+0.2VH2+0.2NbH2+0.1MgH2. From the synthesized mixtures of metal hydrides, the HEAs were produced in HC. The resultant hard alloys Ti0.2Zr0.2Hf0.2V0.2Nb0.2, Ti0.3Zr0.15Hf0.15V0.2Nb0.2 and Ti0.3Zr0.15Hf0.15V0.2Nb0.2Mg0.1 without crushing combusted in Н2 at РH2 = 5-30atm. in SHS mode. As a result, the hydrides of HEAs (Ti0.2Zr0.2Hf0.2V0.2Nb0.2)Н2.05, (Ti0.3Zr0.15Hf0.15V0.2Nb0.2)H2.05 and (Ti0.3Zr0.1Hf0.1V0.2Nb0.2 Mg0.1)H182 were synthesized with H2 content between 2.17-2.42wt.% and H/Me = 1.82-2.05. The repeating the hydrogenation-dehydrogenation processes for 1-3 times confirmed the exceptional cyclic stability of hydrides and the reversible high hydrogen storage capacity of the alloys. The regularities and the mechanism of formation of HEAs and their hydrides were elucidated. The applicability of combination of SHS and HC methods for synthesis of solid solutions of BCC structure HEAs and of their hydrogen-rich hydrides was demonstrated. The remarkable advantages of the developed efficient, low-energy consuming, waste-free and safe method for the synthesis of HEAs and their hydrides can be of commercial interest and attractive to industry, given the current needs for the development of renewable energy, in particular, the solid hydrogen storage facilities.

Two-dimensional Zr2C monolayer as anode material for Li, Na and K ion batteries

In this paper, the electronic properties and storage capacity of Zr2C after adsorption of Li, Na, and K metal ions are systematically investigated with density-functional theory (DFT) based on first-principles calculations. For Li, Na, and K ion adsorption, the negative adsorption energy indicates a strong interaction between the metal ions and the two-dimensional (2D) Zr2C monolayer, which prevents the formation of dendrites, and the adsorbed system has good metallic properties with low diffusion barriers, suitable open-circuit voltages, and high theoretical storage capacities. Our study shows that Zr2C monolayer is a promising anode material for metal-ion batteries.

High-performance flexible CoFe2O4/N-doped carbon nanofiber composite anode materials for sodium-ion batteries

Graphite is traditionally used as an anode material but is unsuitable for use in sodium-ion batteries because it has a low specific capacity and poor safety characteristics, it is therefore necessary to develop alternative anode materials. Flexible CoFe2O4 nanoparticle/N-doped carbon nanofiber films were prepared by electrospinning and calcination. The advantages of this process included inexpensive starting materials, easy preparation, and suitability for commercialization. The inherent shortcomings of CoFe2O4, such as poor electronic conductivity and large changes in volume, were mitigated via elemental doping and the formation of composites with high-quality carbon materials. Nitrogen-doped carbon nanofibers with large specific surface areas and superior mechanical properties were used as the supporting skeleton of the material. These nanofibers limited the volume expansion of CoFe2O4 throughout the cycling process and increased the ion diffusion velocity in the material. The optimal integration of nanoscale CoFe2O4 particles, which possess a higher theoretical specific capacity, with a nitrogen-doped carbon nanofiber conductive framework featuring a crosslinked three-dimensional structure facilitated the infiltration of the electrolyte into the electrode. This integration reduced the diffusion distance of sodium ions and effectively reduced the volume expansion of the material, as well as damage to the material during the electrochemical reaction. After 200 cycles at a current density of 0.1 A g−1, it provided a high sodium storage capacity of 365.7 mA h g−1. The capacity was maintained at 176.3 mA h g−1 even at a high current density of 2 A g−1. Exhibits good cycle stability.

Metal-organic frameworks based on pyrazolates for the selective and efficient capture of formaldehyde

Indoor air pollution is one of the major threads in developed countries, notably due to high concentrations of formaldehyde, a harmful molecule difficult to eliminate. Addressing this purification challenge while adhering to the principles of sustainable development requires the use of innovative, advanced sustainable materials. Here we show that by combining state-of-the-art spectroscopic techniques with density-functional theory molecular simulations, we have developed an advantageous mild chemisorption synergistic mechanism using porous metal (III or IV) pyrazole- di-carboxylate based metal-organic framework (MOF) to trap formaldehyde in a reversible manner, without incurring significant energy penalties for regeneration. A straightforward, environmentally friendly, and scalable synthesis protocol was established for the porous, water-stable aluminum pyrazole dicarboxylate known as Al-3.5-PDA or MOF-303, capable of functioning as a highly efficient and reusable filter. It demonstrates selectivity and high storage capacity for formaldehyde under conditions typical of severe indoor use, such as in housing or vehicle cockpits, including varying VOC mixtures and concentrations, humidity, and temperature, without any accidental release. Furthermore, we have successfully regenerated this sorbent using a simple domestic protocol, ensuring the material reusability for at least 10 cycles.

Estimation of hydrogen solubility in aqueous solutions using machine learning techniques for hydrogen storage in deep saline aquifers

The porous underground structures have recently attracted researchers’ attention for hydrogen gas storage due to their high storage capacity. One of the challenges in storing hydrogen gas in aqueous solutions is estimating its solubility in water. In this study, after collecting experimental data from previous research and eliminating four outliers, nine machine learning methods were developed to estimate the solubility of hydrogen in water. To optimize the parameters used in model construction, a Bayesian optimization algorithm was employed. By examining error functions and plots, the LSBoost method with R² = 0.9997 and RMSE = 4.18E-03 was identified as the most accurate method. Additionally, artificial neural network, CatBoost, Extra trees, Gaussian process regression, bagged trees, regression trees, support vector machines, and linear regression methods had R² values of 0.9925, 0.9907, 0.9906, 0.9867, 0.9866, 0.9808, 0.9464, and 0.7682 and RMSE values of 2.13E-02, 2.43E-02, 2.44E-02, 2.83E-02, 2.85E-02, 3.40E-02, 5.68E-02, and 1.18E-01, respectively. Subsequently, residual error plots were generated, indicating the accurate performance of the LSBoost model across all ranges. The maximum residual error was − 0.0252, and only 4 data points were estimated with an error greater than ± 0.01. A kernel density estimation (KDE) plot for residual errors showed no specific bias in the models except for the linear regression model. To investigate the impact of temperature, pressure, and salinity parameters on the model outputs, the Pearson correlation coefficients for the LSBoost model were calculated, showing that pressure, temperature, and salinity had values of 0.8188, 0.1008, and − 0.5506, respectively, indicating that pressure had the strongest direct relationship, while salinity had an inverse relationship with hydrogen solubility. Considering the results of this research, the LSBoost method, alongside approaches like state equations, can be applied in real-world scenarios for underground hydrogen storage. The findings of this study can help in a better understanding of hydrogen solubility in aqueous solutions, aiding in the optimization of underground hydrogen storage systems.

Amorphous/crystalline heterostructured indium (III) sulfide/carbon with favorable kinetics and high capacity for lithium storage

Amorphous/crystalline heterostructured indium (III) sulfide/carbon with favorable kinetics and high capacity for lithium storage

Construction of Highly Porous and Robust Hydrogen-Bonded Organic Framework for High-Capacity Clean Energy Gas Storage.

Development of highly porous and robust hydrogen-bonded organic frameworks (HOFs) for high-pressure methane and hydrogen storage remains a grand challenge due to the fragile nature of hydrogen bonds. Herein, we report a strategy of constructing the double-walled framework to target highly porous and robust HOF (ZJU-HOF-5a) for extraordinary CH4 and H2 storage. ZJU-HOF-5a features a minimized twofold interpenetration with double-walled structure, in which multiple supramolecular interactions are existed between the interpenetrated walls. This structural configuration can notably enhance the framework robustness while maintaining its high porosity, affording one of the highest gravimetric and volumetric surface areas of 3102 m2 g-1 and 1976 m2 cm-3 among the reported HOFs so far. ZJU-HOF-5a thus exhibits an extremely high volumetric H2 uptake of 43.6 g L-1 at 77 K/100 bar and working capacity of 41.3 g L-1 under combined swing conditions (77 K/100 bar→160 K/5 bar), and also impressive methane storage performance with a 5-100 bar working capacity of 187 (or 159) cm3 (STP) cm-3 at 270 K (or 296 K), outperforming most of the reported porous organic materials. Single-crystal X-ray diffraction studies on CH4-loaded ZJU-HOF-5a reveal that abundant supramolecular binding sites combined with ultrahigh porosities account for its high CH4 storage capacities. Combined with high stability, super-hydrophobicity, and easy recovery, ZJU-HOF-5a is placed among the most promising materials for H2 and CH4 storage applications.

MnO2 nanowires modified reduced graphene oxide thick film cathode for aqueous zinc-ion prismatic battery

Aqueous zinc-ion batteries are an excellent alternative to lithium-ion batteries that can meet the energy requirements while also being safe and eco-friendly. However, developing a suitable cathode material with good energy density and high-rate capability is challenging. In this study, we developed an aqueous zinc-ion battery with a high surface area MnO2 nanowires modified reduced graphene oxide nanocomposite screen printed interdigitated array electrodes and a distinctive aqueous electrolyte comprising 1 M each of ZnSO4 and Na2SO4, 0.1 M MnSO4, and 0.8 mM sodium dodecyl sulfate. The charge-discharge curves reveal that the cathode material exhibits a high reversible storage capacity of 164 mAh g−1 at a current density of 50 mA g−1. The battery retained 99.59% of its Coulombic efficiency after 300 cycles when cycled at a high current rate of 300 mA g−1. The prismatic battery realized exhibited a calculated energy density of 505.5 Wh kg−1 which is higher than previously reported works. On account of the large energy density and high rate capability coupled with non-toxic components, low cost and facile fabrication method, the Zn||MnO2/rGO battery shows good promise for energy storage application.

Development and characterization of mesoporous silica-MgSO4-MgCl2 binary salt composites for low-grade heat storage in fluidized bed systems

Achieving nearly zero-energy buildings requires the efficient utilization and storage of renewable energy. Salt-hydrate-based thermochemical energy storage (TCES) systems are promising due to their high heat storage capacity and minimal seasonal heat loss. However, challenges remain in their commercialization and large-scale application. For instance, TCES systems using magnesium sulphate (MgSO4) provide low temperature lifts due to slow reaction kinetics. Incorporating deliquescent salts like magnesium chloride (MgCl2) can enhance sorption performance but may introduce stability issues such as agglomeration and decomposition. This study presents a novel binary-salt composite combining MgSO4 and MgCl2 within commercial mesoporous silica (CMS) to address these challenges and enhance overall performance. The binary-salt composite powder, with a particle size range of 150–300 μm, is well-suited for use in fluidized-bed reactors, where fast mass and heat transfer promote efficient moisture adsorption, prevent uneven temperature distribution, and reduce agglomeration. Thermogravimetric analysis (TGA) was employed to evaluate the water sorption and desorption behaviour of MgCl2-MgSO4@CMS binary-salt composites with a total salt content of 50 wt% and salt mixing ratios of 3:1, 1:1, and 1:3. The corresponding water sorption capacities were 0.95, 0.68, and 0.57 g/g, respectively. In comparison, the MgSO4@CMS single-salt composite showed a lower water adsorption capacity of 0.47 g/g and required temperatures exceeding 150 °C for complete regeneration. Reactor-scale experiments demonstrated that the MgCl2-MgSO4@CMS composite with a 1:1 salt mixing ratio could be fluidized at low gas velocities on the order of 10−2 m/s, achieving a maximum temperature lift of 24.7 °C and an energy density of 1018 kJ/kg during hydration at 80% relative humidity and 30 °C. Additionally, the binary-salt composite showed good cyclic stability with less particle agglomeration compared to the MgCl2@CMS single-salt composite.

Oxygen-containing groups assist in enhancing Li+/K+ storage: Balancing adsorption and intercalation mechanisms

Porous carbon nanosheets were prepared using a high-temperature solid-phase method and subsequently modified through oxidative acid treatment to introduce oxygen-containing groups. The application and performance of these nanosheets as anodes in lithium-ion and potassium-ion batteries were investigated. The results indicated that the oxidative acid treatment successfully enhanced the porous carbon nanosheets' capacity for storing Li+/K+. Electrochemical analysis revealed that the oxygen-containing groups balanced intercalation and surface storage behaviors, optimizing the nanosheets' storage performance. These modified porous carbon nanosheets (termed SN@PCNs) demonstrated significantly boosted reversible Li+ and K+ storage capacities, achieving 1038.1 mAh⋅g−1 and 371.7 mAh⋅g−1 at 0.1 A g−1, respectively, while maintaining capacities of 443.3 mAh⋅g−1 for Li+ and 153.9 mAh⋅g−1 for K+ at 5.0 A g−1. Furthermore, the study emphasized the significance of a balanced surface capacitance and solid-phase diffusion storage mechanism in attaining high storage capacity and cycle stability. Moderate oxidation and the introduction of oxygen-containing groups were identified as crucial factors in optimizing performance. Additionally, potassium adsorption storage exhibited an advantage over lithium adsorption storage, and the impact of oxygen-containing groups on potassium storage performance was even more pronounced.