Lithium iron phosphate batteries are extensively used across various fields because of their high safety and long cycle life. However, after prolonged use, repeated lithium ion insertion and extraction disrupt the original structure, leading to performance degradation. In the context of the strong demand for lithium resources, research into their restoration and performance enhancement holds significant importance. This study employs a combined solvent–thermal and high-temperature solid-state sintering method, in which ethanol is used as a reducing agent and lithium acetate is used as a lithium source to repair and regenerate waste lithium iron phosphate batteries. The effects of the addition of a lithium source, the solvothermal time, and the solvothermal temperature on the regenerated materials were investigated, and morphological, structural, and electrochemical performance tests were conducted. Additionally, the regenerated materials under optimized conditions were subjected to in-depth testing. The results indicate that, when the amount of added lithium source is 30 mg, the solvent–thermal time is 5 h, and the solvent–thermal temperature is 180°C, the recycled material exhibits optimal electrochemical performance, maintaining an efficiency of more than 90

Tin sulfide composites have been extensively studied because of their high specific capacity and good chemical properties. However, their performance is limited by poor electrical conductivity and volume expansion effects. In this study, CNT-modified SnS composites were synthesized via a step solvothermal method, adjusting the doping of CNTs. Phase analysis confirmed the successful synthesis of the material. The results show that SnS@CNTs-100 has the most uniform morphological distribution and the most stable structure, making it most conducive to ion transport and maintaining structural stability during long-term cycling. The electrochemical performance results show that SnS@CNTs-100 has a high capacity in the initial charge-discharge (1220.8 mAh g−1) and can still maintain 385 mAh g−1 after 100 cycles; after 500 cycles, it has 178.2 mAh g−1 demonstrating good cycling stability. These results indicate that the addition of an appropriate amount of CNTs can effectively retard the volume expansion effect of SnS and improve the electrical conductivity of SnS@CNT composites.

The fundamental understanding of activity differences between metal-rich transition metal phosphides in alkaline hydrogen evolution reaction (HER) remains limited. Here, Co2P and Ni2P nanoarrays grown on nickel foam (NF) were synthesized via hydrothermal and phosphidation methods. XRD, SEM, and XPS confirm phase-pure Co2P@NF (nanowires) and Ni2P@NF (nanosheet-assembled microspheres). In 1-M KOH, Co2P@NF exhibits a lower overpotential (78 mV) than Ni2P@NF (80 mV) at 10 mA cm−2, with Tafel slopes of 67.30 and 69.61 mV dec−1, indicating Heyrovsky-dominated kinetics. Co2P@NF also shows a larger electrochemical surface area (3.6 cm2) and lower charge transfer resistance (1.2 Ω). Density functional theory (DFT) reveals that Co2P has a higher density of states near the Fermi level and more optimal hydrogen adsorption free energy (− 0.66 eV vs. − 0.78 eV for Ni2P), explaining its superior intrinsic activity. This study provides insights into designing efficient non-noble metal phosphide electrocatalysts.

Vanadium redox flow batteries (VRFBs) are regarded as an ideal candidate technologies for large-scale energy storage systems because of their advantages of strong scalability and long cycle life. However, its practical application is limited by the key problem of slow redox reaction kinetics on the electrode surface. In this study, a simple, low-cost and non-polluting method was used to etch the graphite felt to regulate the surface characteristics of the graphite felt electrode. Through the synergistic reaction of oxide and graphite felt at high temperature, a porous carbon layer structure with high roughness was constructed on the electrode surface, and oxygen-containing functional groups. The results of SEM, XPS and Raman tests revealed that as the number of oxygen-containing functional groups on the modified electrode increased, the specific surface area increased by approximately 329

Driven by the global transition to renewable energy, electrocatalytic hydrogen production has attracted significant attention for its green, environmentally friendly nature. However, it faces challenges such as high hydrogen evolution overpotential. Thus, the design of highly active and stable electrocatalytic materials for operation at industrially relevant current densities is imperative. Manganese-based compounds are promising because of their low price and high crustal abundance. Owing to their considerable activity, manganese oxides and sulfides are considered efficient electrocatalysts for facilitating hydrogen evolution. This work leverages hybridization between the p and d orbitals of selenium to regulate the electronic, crystal, and morphological structures of manganese selenide (MnSe), enabling their fabrication on nickel foam (NF) and assessment of their performance. Under optimal conditions, an electrode constructed from MnSe/NF has a hydrogen evolution overpotential (η10) of 169 mV, a reduction of 59 mV compared with that of the bare NF electrode (228 mV). The electrochemically active area, Tafel slope, and charge transfer resistance are 153.1 cm2, 108.6 mV/dec, and 34.29 Ω, respectively. In summary, the MnSe catalyst demonstrates excellent hydrogen evolution performance.

Layered titanium lithium ion-sieve (H2TiO3, HTO) is considered among the most promising adsorbents in liquid lithium extraction technology because of its environmental friendliness, low cost and high H/Ti ratio. In this work, the precursor of Li2TiO3 (LTO) was synthesized by co-doping Zr and F with a high-temperature solid phase method through density functional theory (DFT) calculations and corresponding experiments, and then the doped ion sieve (Zr/F-HTO) is obtained by elution with H2SO4. The specific surface area of Zr/F-HTO is up to 131.64 m2/g, and the adsorption capacity is 68.66 mg/g. The adsorption behavior of Zr/F-HTO on Li+ is consistent with the Langmuir adsorption thermodynamic model and pseudo-second-order kinetic model. In addition, batch experiments revealed that Zr/F-HTO exhibits good lithium selectivity in simulated submerged lithium mother liquor, and the capacity retention rate is as high as 97.7% after five "adsorption-desorption" cycles. The simple economic calculation shows that the adsorbent has good industrial application potential. Therefore, the proposed Zr/F-HTO provides an economical and effective scheme for the efficient extraction of lithium from submerged lithium mother liquor.

In this work, the granulation of titanium lithium-ion sieves and its application in the recycling of waste lithium-ion batteries were studied. To address the problems of poor permeability and fluidity of lithium-ion sieve powder and low circulation efficiency, modified powder Zr/F-HTO was granulated by using a styrene acrylic emulsion and ethyl cellulose as binders. A comparison of the morphology, specific surface area, and adsorption properties of the granular lithium-ion sieve obtained from the two binders revealed that the granular lithium-ion sieve (SA-Zr/F-HTO) bonded with the styrene acrylic emulsion has a more porous surface structure and a larger specific surface area, and thus has a greater adsorption capacity. The results also show that the adsorption process of SA-Zr/F-HTO conforms to the Langmuir adsorption thermodynamic model and pseudo-second-order kinetic model, indicating that the adsorption process is monolayer chemisorption. In addition, SA-Zr/F-HTO showed excellent lithium selectivity and good cycle stability in simulated lithium-containing mother liquor. The results of column adsorption experiments show that SA-Zr/F-HTO has a long penetration time and high adsorption efficiency, which is suitable for continuous operation and provides an effective method for the efficient recovery of lithium in waste lithium-ion batteries.

This study investigated the extraction performance of the DBM (bibenzoylmethane) + Cyanex 923 system, proposing a novel method for the selective recovery of lithium from lithium sulfate solutions. Density functional theory (DFT) calculations were employed to elucidate the synergistic extraction mechanism. The results demonstrated that the DBM + Cyanex923 synergistic system effectively achieved lithium–sodium separation, with the organic phase composition and equilibrium pH significantly influencing the separation efficiency. Under optimized conditions (organic phase: 0.5 mol/L DBM + 1 mol/L Cyanex923; aqueous phase: 2 g/L Li, 50 g/L Na; pH 12; 25°C; phase ratio O/A = 1:1), a single-stage lithium extraction rate of 92.1

Vanadium redox flow batteries (VRFBs) are considered a highly promising large-scale energy storage technology due to their long lifespan, high safety, large capacity, and high efficiency. In practical applications, pentavalent vanadium in the positive electrolyte of vanadium batteries is prone to precipitation under conditions of high temperatures and concentrations, reducing the energy density and cycle life of VRFBs. Therefore, choosing appropriate additives to improve the stability of pentavalent vanadium ions is crucial. This study researched the effects of two hexahydric alcohols (inositol and galactitol) as electrolyte additives on the performance of vanadium-positive electrolyte through X-ray diffraction (XRD), Raman spectroscopy, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge tests. The results show that both inositol and galactitol can improve the electrochemical performance of vanadium-positive electrolyte. At a current density of 80 mA cm−2, the energy efficiency of the battery groups with inositol and galactitol added increased by 1.24

In the domain of hydrogen evolution reaction (HER) cathode catalysts, MXenes-containing materials are considered to possess considerable potential owing to their unique two-dimensional layered architecture. Conversely, the production processes of these materials, together with the selection of diverse nitrogen doping strategies and the underlying mechanisms, remain subjects requiring further investigation. This experiment employed the molten salt method for the synthesis of MXenes. This approach is beneficial as it effectively mitigates the influence of fluorine groups on the electrochemical characteristics of MXenes. A study was conducted on the effects of doping with two distinct nitrogen sources: urea and lithium nitride. The microstructures and electrochemical characteristics were analyzed to ascertain the most effective preparation and nitrogen doping methods. The Ti3AlC2 precursor was specifically etched with CoCl2 in a eutectic salt solution of KCl and LiCl to produce Ti3C2. Subsequently, lithium nitride was selected as the nitrogen source, resulting in the synthesis of MXenes with enhanced hydrogen evolution reaction performance. The studied HER cathode material exhibited a distinctly defined layered structure with significantly increased interlayer gap. This led to an increased surface area and a higher density of active sites. The electrochemical test findings indicated an overpotential of 82 millivolts at a current density of 10 milliamperes per square centimeter, with a Tafel slope of 120.4 millivolts per degree. The electrochemical impedance spectroscopy (EIS) analysis revealed that the series resistance (Rs) is 1.571 Ω, indicating a low value. The charge transfer resistance (Rct) was measured at 78.56 Ω, corroborating the superior performance. The material exhibited exceptional stability throughout the testing phase.

Alkaline water electrolysis is an important method for sustainable hydrogen production, and exploring efficient cathode materials is of utmost importance. In this study, Ni-Mo-P/NF hydrogen evolution cathode materials for alkaline water electrolysis-based hydrogen production were fabricated by electrodeposition method. During this process, with nickel foam (NF) as the substrate, the composition of the plating solution is nickel sulfate, sodium molybdate and sodium hypophosphite. The ions of Ni2+, MoO42− and H2PO2− in the plating solution were reduced and co-deposited on the surface of the foamed nickel, forming a Ni-Mo-P alloy coating. Furthermore, the electrode surface presented a honeycomb-like structure. The Ni-Mo-P/NF cathode electrode material exhibited excellent electrocatalytic performance, as demonstrated by electrochemical performance tests. In a 1 M KOH electrolyte, the hydrogen evolution reaction (HER) has a relatively low overpotential η10 of 0.109 V, with a Tafel slope of 121.8 mV/dec; the AC impedance Rct is 56.47 Ω; the electrochemical specific surface area is 87.6 cm2. This outstanding catalytic activity is attributed to the synergistic effect among Ni, Mo and P. Mo modulates the electronic structure of Ni, enhancing the adsorption and dissociation of water molecules, whereas P increases the overall catalytic efficiency of the material. This study provides valuable references for the development of highly active nonmetal-based cathode materials in the alkaline water electrolysis field

In this work, Ni(OH)2@NF electrode using nickel foam as a substrate and the hydrothermal method was synthesized. Using the secondary hydrothermal method, Co-NiTe-Ni(OH)2@NF was manufactured. The materials were characterized via electrochemical performance tests and physical characterization. Both have good hydrogen evolution reaction catalytic ability, but Co-NiTe-Ni(OH)2@NF is better. With an ECSA of 123.38 cm−2 and an overpotential of just 113 mV, it demonstrated remarkable performance at a current concentration of 10 mV cm−2. Voltage transfer resistance, ascertained via electrochemical impedance testing, was 5.73 Ω. Tafel test slope was 11.75 mV dec−1.

In this paper, with the goal of developing a high-performance silicon-based negative electrode through a reasonable green design using simple magnesium thermal reduction and pickling combined methods. Specifically, we utilize inexpensive photovoltaic waste silicon mud as the silicon source to synthesize porous silicon. Subsequently, we utilized self-produced porous silicon as the raw material and graphene as the coating material to fabricate a graphene-coated porous silicon-based negative electrode material with excellent cycling stability. We employ the PW91 method, which is based on density functional theory (DFT) using the generalized gradient approximation (GGA), to compute the first principles of both silicon-based materials and graphene-coated silicon/graphene composites. The study revealed that the P-Si@RGO composite exhibited excellent electrochemical properties. When adding 150 mL of graphene oxide with a concentration of 0.2 mg/mL. Even after the 100th cycle at a current density of 100 mA center dot g- 1, the specific discharge capacity of the P-Si@RGO electrode remains high at 1167.6 mAh center dot g- 1. At the same time, the results of DFT calculations also show that graphene can improve the conductivity of silicon materials. In summary, the experimental results are consistent with the results of the firstprincipal calculation, indicating that the computer simulation can predict the accuracy of the experiment, verify the empirical conclusions, and indicate the direction for designing the experimental scheme.

The one-step direct current deposition method has been investigated for the preparation of the Ni-Mo alloy and Ni-Mo-W alloy coatings on nickel-foam substrates. Under optimal conditions, binary alloy and ternary alloy electrode materials with excellent properties were prepared, and the corresponding microstructures and electrochemical properties were studied and compared. Scanning electron microscopy was used to characterize the morphology of the Ni-Mo-W/NF porous hydrogen evolution electrode. Compared with those of the Ni-Mo binary coating, the particles on the surface of the ternary coating were more tightly packed, and some of them were also stacked into a double layer; thus, the electrode had more active sites, and the surface of the coating was almost seamless. Under the test conditions of a 1-M KOH solution at room temperature, the hydrogen evolution overpotential, η10, of the Ni-Mo/NF porous hydrogen evolution electrode and the Ni-Mo-W/NF porous hydrogen evolution electrode were 0.128 V and 0.119 V, respectively. The ternary alloy deposition coating had a better electrocatalytic performance for hydrogen evolution. The Tafel slopes, Rct resistances, and the specific active surface areas of the Ni-Mo/NF binary porous electrode and the Ni-Mo-W/NF ternary porous electrode were 135.6 mV/dec and 128.3 mV/dec, 84.13 Ω and 69.23 Ω, and 23.2 cm2 and 63 cm2, respectively. The Ni-Mo-W/NF porous hydrogen evolution electrode had better long-term stability, and the changes in the hydrogen evolution overpotential value were < 10

Silicon monoxide (SiO) has a high theoretical capacity as an anode for lithium-ion batteries, but its poor conductivity and bulk effect can cause the capacity to plummet. The combination of SiO and other materials to form a core-shell mechanism on the surface of SiO can effectively alleviate these problems. In this work, a silicon dioxide (SiO2)/carbon (C) bilayer core-shell structure coated on SiO anode material was designed and synthesized to address the issues inherent in core-shell structures. When the temperature was 900 degrees C, SiO@SiO2@C exhibited an excellent reversible capacity of 2500.08 mAh center dot g- 1 and a first coulombic efficiency of 75.92 %. After 100 charge/discharge cycles, it still retained 1298.25 mAh center dot g- 1 of its capacity. Compared with those of pure SiO, its cycling stability and capacity retention are significantly improved, providing a new approach for anode materials in lithium-ion batteries.

Molybdenum disulfide (MoS2) is considered a promising non-noble metal catalyst for the hydrogen evolution reaction (HER) due to its unique layered structure, natural abundance, and excellent intrinsic catalytic performance. However, its inherent problems such as poor conductivity, slow electron transfer kinetics, and coexistence of multiple crystal phases hinder the industrial application of MoS2 in the HER. To address these challenges, a mixed-phase MoS2 containing both 1 T and 2H structures was synthesized directly on pretreated nickel foam (NF) using a simple solvothermal method. The resulting MoS2/NF hybrid synergistically combines the excellent electrical conductivity and three-dimensional porous framework of NF with the high catalytic efficiency of MoS2, leading to enhanced MoS2 HER performance. In 1 M KOH, the composite achieves an overpotential of just 151 mV and a Tafel slope of 98.9 mV dec−1 at 10 mA cm−2, surpassing that of bare NF and several reported MoS2-based catalysts. The findings of this work serve as a reference for designing efficient electrocatalysts based on non-precious metals.

Using ammonium metavanadate as the raw material, vanadium trioxide was prepared by using ammonia gas produced by the self-thermal decomposition of ammonium metavanadate and external carbon powder as the reducing agent in a tube furnace. The effects of the reaction temperature, reaction time, and carbon content on the purity of vanadium trioxide were investigated. The results show that high-purity vanadium trioxide with a V content higher than 67

Hydrogen production by electrolysis of water is a clean and efficient green hydrogen production technology. The core of improving hydrogen production efficiency is to obtain electrocatalysts with excellent performance. In this study, CuS/NF material was synthesized by one-step hydrothermal method as a hydrogen evolution catalyst, and its performance was evaluated by physical characterization, electrochemical test, and first-principles calculation. The CuS/NF hydrogen evolution catalyst has a nano-spherical spatial structure. This special structure increases the area of electrocatalytic activity, facilitates electron transfer, and improves HER efficiency. When the current density is 10 mV/cm2, the overpotential is 156 mV, the Tafel slope is 121.43 mV/dec, the electrocatalytic activity area is 177.5 cm2, the charge transfer resistance is 13.424 Ω, and the material maintains stability over 12 h. The hydrogen evolution performance of the CuS/NF electrode is better than that of the blank nickel foam electrode. This experiment provides new ideas and directions for the application and progress of copper-based catalysts in the field of hydrogen evolution from electrolytic water.

Vanadium dioxide (VO2) exhibits reversible thermal phase transitions, with a transition temperature near room temperature, making it a promising functional material for phase change applications. However, VO2 thin films face challenges such as a trade-off between luminous transmittance and solar modulation capability, as well as a phase transition temperature that is too high for practical use. This study addresses these issues by synthesizing Eu-doped VO2 thin films using a novel hydrothermal-assisted electrophoretic approach. The impact of Eu doping on the structural, morphological, thermal, optical, and mechanical properties of VO2 films was comprehensively analyzed. Key findings reveal that Eu doping increases lattice spacing and results in a flower-like microstructure. At different Eu doping concentrations, the phase transition temperature has decreased, and the luminous transmittance and solar modulation capability have increased. In addition, the hardness and elastic modulus of the film have both been improved compared with the undoped thin film.

In this study, a hybrid approach using the Stöber and solvent extraction techniques was employed to synthesize mesoporous silicon-coated VO2 nanomaterials (VO2@m-SiO2, VmS) with controllable pore sizes and shell thicknesses. This synthesis was aimed at elucidating the influence of mesoporous silicon coatings on the thermochromic effect and optical properties of VO2. Experimental findings reveal that the mesoporous silica architecture markedly improve the phase-transition hysteresis of VO2 while mitigating the Mie effects attributable to particle coarsening, under the appropriate shell thickness. Furthermore, concomitant with the enlargement of the mesoporous aperture, the Tlum and ΔTsol of the VmS/PVB films also exhibit upward trends. Tlum reaches 73.33% and 62.24% in VmS3/PVB and VmS5/PVB, peak ΔTsol reaches 5.16% in VmS5/PVB. The facile synthesis procedure of VmS, in conjunction with its superior performance across phase transition, optics, and thermal insulation metrics, offers a viable pathway for industrial-scale deployment of VO2(M) in smart window applications.