Search Results (2,337)

To address the capacity decay of NCM811 caused by microcracks and cation disorder during cycling, La, Al, and F tri-doped micron-sized single-crystal NCM811 material with a LiNbO₃ coating was synthesized via a facile co-solvent method. Using a mixed glucose–urea thermal solution as the reaction medium, metal salts were incorporated, followed by step-wise sintering, ball-milling, heat treatment, and wet-chemical coating. This approach enables atomic-level precursor mixing and ensures homogeneous element distribution. La³⁺ enlarges the lithium layer spacing to enhance ion diffusion and Al³⁺ suppresses Ni³⁺ reduction to Ni²⁺, mitigating cation mixing and improving conductivity, while F⁻ stabilizes the crystal structure via its strong electronegativity. The LiNbO₃ coating protects the interface from electrolyte attack, and the single-crystal morphology effectively suppresses microcracking. Compared to unmodified single-crystal NCM811 prepared identically, the modified material exhibits reduced cation disorder, improved crystallinity, and superior thermal stability. Electrochemical tests in half-cells with 1 M LiPF₆/(EC/EMC/DMC) electrolyte (2.8–4.3 V) show an initial discharge capacity of 208.32 mAh/g at 0.1 C and 194.05 mAh/g at 1 C. After 200 cycles at 1 C, the capacity retention remains at 92.21%, exceeding the market average. Rate performance is also notably enhanced, with the 5 C discharge capacity increasing from 141.12 mAh/g (unmodified) to 166.81 mAh/g, demonstrating improved kinetics and structural stability. Full article

Photosynthetic algae–microbial fuel cells (PAMFCs) are attractive for energy-positive wastewater treatment and carbon mitigation. However, PAMFC performance under continuous flow is often constrained by limited cathodic electron-acceptor supply and unstable photosynthetic biofilms, while the extent to which cathode interfacial engineering can stabilize diurnal power output and assimilative NH₄⁺–N removal remains unclear. In this study, the sponge-like and petal-like ZnO_0.2-NiO@rGO-modified carbon fibers (ZnO_0.2-NiO@rGO-pCFs and ZnO_0.2-NiO@rGO-pCFp) and pre-fabricated carbon felt (pCF) were used as cathode materials to construct three sets of PAMFC systems. Under light–dark cycling, the engineered cathodes reached steady operation within about 6.5 d and increased the steady-state voltage to approximately 0.35 V, compared with approximately 0.08 V for pCF. Under continuous-flow conditions, cathodic NH₄⁺–N removal exhibited a stable diurnal rhythm, with higher removal during illumination at about 43–51% than in the dark at about 29–30%, consistent with algal assimilation as the primary nitrogen sink, while cathode modification mainly improved the cathodic microenvironment and response stability. Compared with pCF, the ZnO_0.2–NiO@rGO cathode enriched a more even, Chlorophyta-dominated algal biofilm with an approximate relative abundance of 80%, indicating that its selective interfacial environment favors biofilm stabilization and sustains in situ oxygen production and cathodic electron-acceptor supply. Consequently, the composite cathode enhanced voltage output and stabilized light-enhanced, assimilative NH₄⁺–N removal under aeration-free operation, while establishing an interpretable link between electrochemical performance and 18S rDNA-derived community assembly features, thereby providing a low-cost cathode design basis for nitrogen removal in wastewater treatment. Full article

Tungsten is an extremely durable metal with a wide range of industrial applications and its toxicity is relatively low, although chronic exposure to its compounds can lead to adverse health effects. This paper proposes a method for the determination of trace amounts of tungsten using cathodic stripping voltammetry (CSV). A hybrid structure based on a mixture of multi-walled carbon nanotubes and spherical glassy carbon was used as the working electrode, on the surface of which a film of lead was formed during the measurement to increase the efficiency of the determination. A comprehensive optimization of the analytical parameters, including accumulation potential and time, signal recording conditions and electrolyte solution composition, was carried out to maximize sensitivity and improve the signal-to-noise ratio. The method developed achieved a detection limit for tungsten of 3 × 10⁻¹⁰ mol L⁻¹, demonstrating its high sensitivity. The working electrode showed selectivity, signal reproducibility and resistance to the presence of potential interferences. The reliability and applicability of the proposed solution were confirmed by applying the method to the analysis of real environmental samples and certified reference materials, with satisfactory results. The presented analytical procedure represents a promising tool for the routine determination of tungsten in complex real matrices. Full article

Pt-based catalysts remain the most effective materials for the oxygen reduction reaction (ORR) at the cathode of proton exchange membrane fuel cells (PEMFCs); however, platinum scarcity and high cost severely limit the large-scale deployment of the technology. Improving catalytic activity and durability through precise control of nanoparticle morphology is therefore crucial for reducing costs and enhancing sustainability, enabling PEMFC widespread adoption. In this context, carbon-supported Pt-based nanoparticles with a 30 wt.% Pt loading were synthesized by an organometallic chemistry approach using hexadecylamine (HDA) as a stabilizer, allowing fine control over nanoparticle morphology. Two distinct synthesis pathways (one-pot and two-step procedures) were used to prepare platinum catalysts supported on KetjenBlack EC-300J (KB), and their influence on the electrocatalytic activity of the obtained nanomaterials was studied. Furthermore, the effect of HDA stabilization on catalyst performance was investigated. Directly synthesized Pt/KB catalysts exhibited similar ORR mass activity, regardless of whether or not HDA was present. Pt/KB prepared by the two-step procedure showed a significantly lower performance. Additionally, despite a larger loss of electrochemical surface area during an accelerated stress test compared to a commercial Pt/C reference, Pt^HDA/KB and Pt/KB catalysts maintained stable mass activity and limited specific activity degradation, highlighting the beneficial effect of nanoparticle stabilization in the presence of HDA on prolonged electrocatalyst cycling. Full article

Lithium–sulfur (Li-S) batteries hold great promise for next-generation energy storage, offering high theoretical energy density and cost-effectiveness. However, challenges like sulfur’s low conductivity, polysulfide dissolution, and significant volume changes limit their practical application. This study addresses these issues by investigating porosity-engineered carbon hosts, specifically potassium hydroxide (KOH)-activated Black Pearl carbons (BP2000, BP1300, and BP800). Varying KOH-to-carbon ratios allowed precise tailoring of micro- and mesoporous structures, optimizing sulfur loading, electrolyte infiltration, and ion transport. Composites were characterized by TGA, NLDFT, SEM, XRD, and FTIR and electrochemically (cycling, CV, EIS). The KOH-modified BP2000 1:1 cathode, exhibiting the highest mesopore volume increase, demonstrated superior electrochemical performance, including enhanced cycling stability, rate capability, and reduced charge-transfer resistance. These findings emphasize the importance of optimizing pore distribution in carbon hosts for high-performance Li-S batteries and provide valuable insights for advanced energy storage material design. Full article

The strong adhesion between cathode materials and aluminium (Al) foil substrates presents a significant challenge in the recycling of spent lithium-ion batteries (LiBs). Conventionally, high temperatures and high concentrations of costly organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) are used to enhance ultrasonication-based delamination. In this study, a novel, eco-efficient approach was demonstrated for delaminating cathode materials from Al foil using a low-concentration organic citric-acid-assisted low-power ultrasonic treatment coupled with a gentle, low-power-per-volume mechanical mixing system at room temperature. The separation mechanism was attributed to the structure disruption, possibly swelling, of the polyvinylidene fluoride (PVDF) binder using low-concentration citric acid and the cavitation effects induced by ultrasound. Key parameters influencing the delamination efficiency included the solvent type, temperature, ultrasonic power, and treatment duration. Under optimised conditions, citric acid was used as the sonication reagent, with a process temperature of 20 °C, 60 W ultrasonic power, and 80 min of ultrasonication; a delamination efficiency of approximately 92% was achieved. The recovered cathode materials exhibited low agglomeration, favouring subsequent leaching processes. This work proposes an environmentally friendly and effective method for cathode and Al foil recovery from spent LiBs, integrating manual dismantling, ultrasonic treatment, and material separation. Full article

Urea electrolysis has emerged as a promising alternative to conventional water electrolysis for hydrogen production, owing to low electrical energy consumption as well as organic wastewater. However, the practical implementation of this approach is primarily constrained by the lack of cost-effective and efficient electrocatalysts. Thus, the development of earth-abundant, non-precious metal-based bifunctional electrocatalysts toward both the hydrogen evolution reaction (HER) and the urea oxidation reaction (UOR) is of critical importance. In this context, nanostructured, reduced nickel-cobalt tungstate supported on Ni foam is fabricated as a binder-free, freestanding electrode via a two-step hydrothermal process followed by partial thermal reduction. By systematically tuning the precursor concentrations of Ni, Co, and W, the morphology and electronic structure of the material are effectively modulated. The introduction of oxygen vacancies through partial thermal reduction plays a key role in enhancing charge transport properties. The optimized NiCo@W_0.5/NF electrode exhibits a porous, flower-like architecture and demonstrates excellent bifunctional electrocatalytic activity toward both UOR and HER, accompanied by improved mass transport behavior. When employed as both the anode and cathode for overall urea electrolysis, NiCo@W_0.5/NF requires a low cell voltage of only 1.68 V to achieve a current density of 100 mA cm⁻² and delivers impressive operational stability in an optimized electrolyte composed of 3 M KOH and 0.33 M urea. These results indicate that NiCo@W_0.5/NF is a highly promising and efficient bifunctional electrode material for urea assisted hydrogen production. Full article

The pursuit of high-energy-density cathode materials has positioned LiNiO₂ as a promising candidate due to its high theoretical capacity. However, its practical application is hindered by structural instability, cation mixing, and sluggish Li-ion mobility. This study presents a strategic co-doping approach to enhance the electrochemical performance of R3m-structured LiNiO₂ by introducing Na at the Li site and Nb/Al/W at the Ni site. First-principles calculations based on density functional theory (DFT), combined with the bond valence sum energy (BVSE) method, were employed to evaluate the structural, electronic, and transport properties of the doped systems. The optimized lattice parameters reveal that co-doping induces lattice expansion and suppresses cation disorder, thereby improving structural integrity. Formation energy validates the thermodynamics of the modified structures. Furthermore, BVSE-based ion migration mapping shows that Na/Nb and Na/Al co-doping significantly broadens Li-ion diffusion pathways and lowers migration barriers compared to pristine LiNiO₂. These results demonstrate that dual-site doping is an effective strategy to overcome intrinsic limitations of Ni-rich layered oxides, offering a rational design route cathode for next-generation Li-ion battery. Full article

Potassium-ion batteries hold great promise for large-scale energy storage, but their commercialization is hindered by the large ionic radius of potassium, which causes sluggish kinetics and severe volume expansion in anode materials. To address this, we present a scalable spray-drying strategy coupled with NaCl salt-templating to synthesize hierarchical porous carbon/vanadium sulfide microspheres (p-V₃S₄/C MS). In this structure, V₃S₄ nanoparticles are uniformly encapsulated within a dextrin-derived amorphous carbon matrix, and pores are formed via selective NaCl etching. This unique architecture accommodates volume fluctuations while providing rapid ion diffusion pathways. As a result, the p-V₃S₄/C MS anode exhibits outstanding electrochemical performance, maintaining a reversible capacity of 107 mA h g⁻¹ after 2000 cycles at 2.0 A g⁻¹, and achieves a high pseudocapacitive contribution of 93% at 2.0 mV s⁻¹. Furthermore, a full cell paired with a Prussian blue (PB) cathode demonstrates practical viability and robust reversibility. Our findings demonstrate that this structural engineering effectively mitigates internal resistance and structural degradation, offering a cost-effective route for mass-producing high-performance anodes for next-generation energy storage. Full article

A hybrid material based on the copolymerization of EDOT (3,4-ethylenedioxythiophene) and Py (pyrrole), 1:1 monomer ratio, onto multi-walled carbon nanotubes (MWCNTs) was synthesized through a multistep functionalization approach. The resulting P(EDOT-co-Py)@MWCNT hybrid, poly(3,4-ethylenedioxythiophene-co-pyrrol)@MWCNT hybrid, was characterized by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). These characterizations confirmed the successive functionalization steps, the effective anchoring of the monomers, and the subsequent formation of the copolymer. Transmission electron microscopy (TEM) images revealed a homogeneous polymer coating along the nanotube surface while preserving the structural integrity of the MWCNTs throughout the functionalization and polymerization processes. The P(EDOT-co-Py)@MWCNT hybrid was evaluated as an active electrode material for aluminum-ion storage in an aqueous aluminum sulfate electrolyte. The system exhibited two distinct charge-storage mechanisms: at high current densities, proton surface adsorption dominated, whereas at lower rates, a faradaic contribution associated with polymer chain redox activity and the reversible extraction/insertion of Al³⁺ became prevalent. The hybrid electrode delivered high specific capacities, reaching 200.6, 106.3, and 44.3 mAh g⁻¹ at 0.10, 0.25, and 0.50 A g⁻¹, respectively. These values are comparable to—or even exceed—those reported for similar cathodic materials designed for Al³⁺ storage, highlighting P(EDOT-co-Py)@MWCNT hybrid as a highly promising cathode candidate for aqueous aluminum-ion energy-storage systems. Full article

Amid growing environmental pressure and increasing demand for resource sustainability, the efficient recovery of valuable metals from spent lithium-ion batteries (LIBs) has become a critical challenge in the field of resource recycling. Therefore, a novel approach is presented for selective lithium (Li) and manganese (Mn) separation from LiNi_xCo_yMn_1−x−yO₂ by combining carbothermic reduction roasting and selective leaching. Low-cost glucose (C₆H₁₂O₆) was selected as the reduction roasting reductant, which converts the cathode materials into water-soluble lithium carbonate (Li₂CO₃), water-insoluble cobalt (Co), nickel (Ni), and manganese oxide (MnO). Wet magnetic separation was employed to preferentially extract Li while simultaneously removing excess carbon from Ni, Co, and MnO. Under optimal roasting conditions at 600 °C for 90 min followed by wet magnetic separation with a liquid–solid ratio of 30 mL/g for 30 min, 95.42% of Li was preferentially extracted. Subsequently, at a formic acid (HCOOH) concentration of 1.6 mol/L, liquid–solid ratio of 6 mL/g, and leaching time of 30 min, 94.29% of Mn was selectively extracted from the wet magnetic separation products, whereas Ni and Co were leached at 6.13% and 7.22%, respectively. The acid-leaching residue can be recycled as a Ni-Co alloy. Full article

To enhance the electrochemical performance of NiMn layered double hydroxides (LDH), this study explores the Ce-doped NiMn-LDH (CeNiMn-LDH) as a cathode material for supercapacitors. In the CeNiMn-LDH structure, partial substitution of Ni/Mn ions by Ce increases the number of active sites, facilitates electron transfer, and improves current density, leading to a significant enhancement in the electrochemical properties compared with NiMn-LDH. Experimental results show that the 0.3CeNiMn-LDH electrode delivers excellent electrochemical performance, achieving a specific capacitance of 1928.16 F/g at a current density of 1 A/g. Furthermore, an assembled CeNiMn-LDH//AC asymmetric supercapacitor exhibits an energy density of 36.36 Wh/kg and a power density of 850 W/kg at 1 A/g. Therefore, the strategy of employing CeNiMn-LDH offers an effective technical approach for improving the electrochemical performance of supercapacitor cathode materials, demonstrating considerable potential for practical applications. Full article

Traditional lithium-ion battery recycling relies mainly on pyrolysis or chemical leaching to separate current collectors from electrode materials, inevitably resulting in secondary pollution. In contrast, eddy current separation (ECS) applied to crushed lithium-ion battery residues can substantially reduce the introduction of contaminants while minimizing material losses. However, the heterogeneous composition and diverse surface characteristics of crushed battery products, together with the conductivity degradation of electrode materials after long-term use, make conventional empirical particle–trajectory correlations inadequate for accurate optimization of ECS operating parameters. In addition, the coupling between process parameters and the resultant forces acting on conductive particles, as well as the associated separation trajectories, remain insufficiently understood, which severely limits process controllability. A force–trajectory model was therefore developed for spent current collectors and conductivity-degraded LiFePO₄ to describe their particle dynamics in an alternating magnetic field. The results demonstrate that the trajectory of LiFePO₄ is very similar to that of non-conductive materials, thereby facilitating its effective separation from metallic components in battery scrap. Eddy current separation experiments further confirm the accuracy of the model predictions with respect to separation trajectories and the influence of key process parameters. On this basis, optimization of the operating parameters increased the separation efficiency of the cathode material to above 95.1%. The clarified ECS mechanism for current collectors and electrode materials provides new insights into the mechanical pre-sorting and mechanistic understanding of lithium-ion battery fragments, thereby contributing to reductions in contaminant introduction during battery material recycling. Full article

The rapid increase in end-of-life lithium-ion batteries demands sustainable recycling routes for lithium recovery. This work presents a novel integrated hydrometallurgical–electrodialysis process designed specifically for recovering lithium from off-specification NMC cathode materials while enabling full reagent recyclability. Selective leaching with oxalic acid was optimised by setting the water-to-oxalic acid dihydrate ratio (H₂O/OA·2H₂O) to 7.3:1 w/w, achieving 81% lithium extraction at room temperature within 2 h while limiting the co-dissolution of Ni, Co and Mn to 0.2%, 1.6% and 1.7% by weight, respectively. The resulting leachate was processed in a four-chamber electrodialysis cell equipped with two Nafion 117 cation-exchange membranes and one Neosepta AMX-fmg anion-exchange membrane operating at −1.6 V versus Ag/AgCl, enabling 96% lithium recovery and 98% oxalic acid recovery. The regenerated oxalic acid stream (41.8 g L⁻¹) was fully restored to its initial concentration and reused in successive cycles without performance loss. Subsequent precipitation of lithium with Na₂CO₃ yielded 99.3%-pure Li₂CO₃. This combined leaching–electrodialysis–precipitation presents a high selectivity, low-waste, circular recovery system, offering a scientifically original approach that integrates reagent regeneration with high-purity lithium production. Full article

The rapid expansion of lithium-ion battery (LIB) applications and the imminent surge in end-of-life batteries have intensified the demand for efficient, scalable recycling technologies. Physical separation of cathode and anode materials is a crucial pretreatment step that enables high-value metal recovery and direct material regeneration. This review critically examines recent advances in three major physical separation technologies—magnetic separation, gravity separation, and flotation—for processing spent LIB electrodes. Rather than offering a descriptive summary, the review systematically analyzes separation mechanisms, key controlling parameters, and pretreatment strategies across representative cathode chemistries, including LiFePO₄ (LFP), LiCoO₂ (LCO), and Ni–Co–Mn (NCM) systems. Particular emphasis is placed on emerging flotation-enhancement strategies, such as nanobubble-assisted and ultrasonic-enhanced flotation, and their underlying mechanistic roles in improving selectivity and recovery. Comparative evaluation indicates that magnetic separation has reached industrial maturity for LFP–graphite systems but remains chemistry-specific. Gravity separation is effective for coarse particles and centrifugal-assisted graphite recovery yet shows limited selectivity for fine particles. Flotation has become the dominant research focus for complex, fine-particle separations due to its tunable surface chemistry. Despite significant laboratory progress, challenges remain, including incomplete binder removal, limited understanding of electrode surface reconstruction during pretreatment, fine-particle entrainment, and the gap between bench-scale research and industrial implementation. Future research priorities include green reagent development, intelligent separation control, and integration with direct regeneration routes to advance closed-loop LIB recycling towards sustainable development. Full article