Search Results (722)

When metal oxides are employed as anodes in lithium-ion batteries, their practical application is often constrained by sluggish reaction kinetics. Structure optimization and heterointerface regulation are effective strategies for improving the aforementioned issue. Herein, a series of Co₃O₄/ZnCo₂O₄ heterostructured materials with hollow structures is prepared. The effects of the two-phase ratio on the interfacial activity and electrochemical performance are systematically investigated. Among them, the optimized Co₃O₄/ZnCo₂O₄-2 material exhibits enhanced interfacial interactions and abundant oxygen vacancies, which optimize the local electronic environment and facilitate charge transfer. Electrochemical test results indicate that the Co₃O₄/ZnCo₂O₄-2 anode maintains a reversible capacity of 582.4 mAh g⁻¹ after 1000 cycles at 1 A g⁻¹, demonstrating good cycling stability. Furthermore, the full cell assembled with a LiFePO₄ cathode maintains a discharge capacity of 115.9 mAh g⁻¹ after 100 cycles at 0.2 C, validating the practical application potential of the material. This work reveals the key role of interface regulation in boosting Li⁺ diffusion kinetics of transition metal oxides, providing new insights for the rational design of heterostructured anodes. Full article

The economic viability of circular biorefineries is fundamentally constrained by the energetic and thermodynamic limits of conventional downstream processing. This critical review examines the paradigm shift toward electro-driven membrane separations, establishing them not merely as alternative filtration devices, but as active, programmable electrochemical interfaces. Moving beyond classical bulk-desalination models, the analysis elucidates the complex reactive-transport physics governing bio-based chemical recovery, where localized pH modulation, electrostatic gating, and field-induced speciation dictate molecular discrimination. The manuscript critically benchmarks the inescapable macro-scale thermodynamic tradeoff among interfacial selectivity, volumetric productivity, and specific energy consumption (kWh/kg). Furthermore, it evaluates the integration of active 2D nanoconfined materials (e.g., MXenes) and rigorously critiques the severe performance degradation modes—specifically electro-biologically coupled fouling and anodic oxidation—that paralyze industrial scale-up. Ultimately, this review outlines a strategic mandate for the fully electrified biorefinery, where continuous in situ product recovery, artificial intelligence-guided module design, and autonomous cyber-physical control systems converge to eliminate legacy thermal unit operations and seamlessly integrate biomanufacturing with decarbonized electrical grids. Full article

Fast-charging lithium-ion batteries require graphite anodes with low ionic transport resistance, yet systematic links between electrode manufacturing parameters and fast-charge performance remain scarce. This study shows that twin-screw extrusion (TSE) process conditions control electrode tortuosity, the geometric complexity of ionic pathways, by reshaping the binder network architecture without altering active material integrity. A central composite experimental design combined with multi-scale diagnostics identifies pore network tortuosity as the primary transport bottleneck. The optimized mild kneading condition (K4: 60 $\mathrm{wt}\%$ kneading zone solids, 7% kneading length, gentle screw design) reduces the 8–80% state-of-charge (SOC) charging time by $14.9$% relative to the intensive baseline (B1–B3: 70 $\mathrm{wt}\%$, 50% kneading length), matching conventional batch mixing. Regression analysis confirms a strong correlation between tortuosity and fast-charge performance ($R^2=0.86$), whereas the correlation with charge-transfer resistance is weaker ($R^2=0.59$). Mechanistically, mild kneading promotes reversible, sterically stabilized carboxymethyl cellulose (CMC) networks consistent with extended “loop-tail” polymer conformations. Intensive kneading is consistent with the formation of bridging gels that fail to arrest binder migration during drying and clog surface pores. A Pore-Homogeneity Index (PHI), derived from mercury porosimetry, quantifies the resulting microstructural heterogeneity, correlates with tortuosity ($R^2=0.76$), and characterizes pore network uniformity. The results identify local stress intensity as a primary factor influencing binder network formation and support tortuosity as an adjustable design parameter in continuous anode processing. Full article

Ti₃C₂T_x MXene is an attractive conductive scaffold for lithium-ion battery anodes owing to its two-dimensional structure, hydrophilic surface chemistry, and tunable interlayer spacing; however, pristine MXene generally exhibits moderate lithium-storage capacity and suffers from restacking-induced loss of accessible active sites. In this study, Ti₃C₂T_x MXene@ZnO composites were prepared by growing ZnO on Ti₃C₂T_x MXene nanosheets with controlled growth times of 1, 2, and 3 h. The materials were characterized by FE-SEM, XRD, and N₂ adsorption–desorption measurements, and their electrochemical performance was evaluated in CR2032-type half-cells. Structural analyses showed that MZ-2h exhibited a more uniform distribution of ZnO particles, increased MXene interlayer spacing, and the highest BET surface area (42.77 m² g⁻¹) and total pore volume (0.1027 cm³ g⁻¹), whereas excessive ZnO growth for 3 h caused particle aggregation and reduced pore accessibility. Electrochemical measurements showed that MZ-2h delivered the best rate capability, maintaining 182.4 mAh g⁻¹ at 0.2 C and 48.0 mAh g⁻¹ at 5 C, together with the highest second-cycle Coulombic efficiency of 88.4%. These results demonstrate that controlling ZnO growth time is an effective strategy for balancing ZnO-derived lithium-storage contribution, particle dispersion, pore accessibility, and the MXene-based framework in Ti₃C₂T_x MXene-based hybrid anodes. Full article

High lithium and manganese oxides (HLMs), also known as lithium- and manganese-rich oxides (LMR), are an alternative to the state-of-the-art (SoA) cathode materials for Li-ion battery cells due to their high specific capacity, working potential, and potential elimination of cobalt from their composition. Nevertheless, they are claimed to undergo accelerated capacity and potential fade. In this work, an extensive electrochemical characterization is conducted while revisiting the most relevant literature on HLM. The classical galvanostatic cycling is used to conduct differential voltage and incremental capacity analyses, while impedance spectroscopy and galvanostatic intermittent titration techniques are applied to complement this test. The results are complemented with online electrochemical mass spectrometry and postmortem characterization. Loss of anode active material is identified as the main degradation mechanism, aggravated by potential slippage. Moreover, the hypotheses on degradation mechanisms are further confirmed by changing the voltage cutoffs of the cells, limiting the Li₂MnO₃ activation. The results are benchmarked with SoA LiNi_0.8Mn_0.1Co_0.1O₂-based cells with a promising balance for HLM in some cases. This work serves as a guide to assist in the interpretation (and avoid misinterpretation) of the results with Li-ion batteries consisting of HLM electrodes. Full article

The development of highly efficient and low-cost electrocatalysts for the urea oxidation reaction (UOR) is crucial for advancing urea fuel cell technologies. In this work, MgZnFe-layered double hydroxide (LDH), LDH/BDC-MOF, and LDH/1,2,4-triazole (LDH/TZ) nanocomposites were successfully synthesized via a simple one-pot co-precipitation method. The structural, morphological, textural, and thermal properties of the prepared materials were investigated using XRD, FTIR, SEM, EDX, BET, and TGA analyses. SEM observations revealed that pristine LDH consisted of stacked thin nanosheets with significant layer aggregation, whereas LDH/BDC-MOF exhibited MOF-pillared structures and LDH/TZ formed a highly porous interconnected three-dimensional network that effectively suppressed nanosheet restacking. BET analysis showed a remarkable enlargement in pore size from 6.7 nm for LDH to 34.5 nm for LDH/TZ. The electrocatalytic performance toward UOR was evaluated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in 1.0 M KOH, containing different urea concentrations. Among all investigated electrodes, LDH/TZ exhibited the highest catalytic activity, delivering anodic current densities of 106, 132, 166, 180, and 202 mA cm⁻² at urea concentrations of 0.2, 0.4, 0.6, 0.8, and 1.0 M, respectively. Furthermore, LDH/TZ displayed a lower onset potential of 0.41 V compared with 0.49 V for LDH/BDC-MOF and 0.56 V for pristine LDH. The enhanced activity was further supported by a high double-layer capacitance of 9.7 μF cm⁻², a large electrochemically active surface area of 0.24 cm², and a low charge-transfer resistance of 2.9 Ω. Chronoamperometric measurements demonstrated excellent durability with a stable current density of approximately 73 mA cm⁻² after 3600 s, while cyclic stability reached 94% after 100 cycles. The superior performance of LDH/TZ is attributed to the synergistic effect of the nitrogen-rich triazole ligand, enlarged pore structure, enhanced active-site exposure, and accelerated charge-transfer kinetics, highlighting its strong potential as an efficient electrocatalyst for direct urea fuel cell applications. Full article

The present study reports the application of a gold microelectrode array to determine copper(II) ions by anodic stripping voltammetry (ASV). The microelectrode characterization of the presented working electrode was investigated. Moreover, the way of its preparation ensures its reusability and eco-friendly character, thanks to the use of environmentally benign electrode material. The procedure does not require modification of the surface of the working electrode. Main experimental parameters were optimized, including pH and a concentration of the supporting electrolyte, activation and deposition conditions, and square wave parameters. The calibration graph was linear in the range of Cu(II) concentrations from 2 × 10⁻⁹ to 2 × 10⁻⁷ mol L⁻¹ (with a deposition time of 30 s) and from 5 × 10⁻¹⁰ to 5 × 10⁻⁸ mol L⁻¹ (with a deposition time of 90 s; RSD was 4.7% (n = 3) for a 1 × 10⁻⁸ mol L⁻¹ of Cu(II)). The limit of detection was equal to 1.93 × 10⁻¹⁰ mol L⁻¹ (t_acc = 90 s). The correctness of the developed procedure was successfully checked by analysis of certified reference material and a tap water sample, confirming the possibility of its practical application. Satisfactory recovery values were also obtained during the analysis of an environmental water sample. Full article

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with the aim of creating efficient materials for hydrazine oxidation (HzOR) and direct hydrazine–hydrogen peroxide fuel cells (DHHPFC, N₂H₄–H₂O₂). The composition, structure, and surface morphology of the created materials were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The activity of the AWC, AWC–Co–N, and AWC–Cu–N catalysts for HzOR was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). N₂H₄–H₂O₂ fuel-cell tests were performed by applying the catalysts as both the anode and cathode. It was found that all materials retained a hierarchical porous carbon framework, while metal incorporation altered surface compactness. Cobalt doping produced well-dispersed Co nanoparticles and abundant Co–N–C coordination sites, whereas Cu introduction resulted in moderately compact structures with uniformly distributed Cu-based nanoparticles. Electrochemical measurements demonstrated that both metal dopants enhanced HzOR activity, with the catalytic performance following the order of AWC–Co–N > AWC–Cu–N > AWC. Fuel-cell testing further confirmed this trend: AWC–Co–N achieved the highest maximum power density (30.4 mW cm⁻²), outperforming AWC–Cu–N (17.7 mW cm⁻²). These results identify AWC–Co–N as a highly effective bifunctional electrocatalyst for DHHPFCs. Full article

Alkaline nickel zinc batteries feature high safety, low cost and eco-friendly characteristics, making them highly promising for large-scale energy storage deployment. However, their practical application is severely constrained by the cathode’s electrical conductivity, available active sites, and cycling stability. Herein, vertical 2D hierarchical flake-like NiCoS_x arrays were in situ grown on nickel foam (NF) via a facile alkali-free solvothermal and in situ sulfidation approach. This highly interconnected and open porous flaky structure significantly shortens the ion diffusion pathways, exposes abundant redox-active sites, and accelerates electron transport, imparting excellent rate performance and superior long-cycle stability to the material. The optimized NiCoS_x/NF electrode achieves a high specific capacity of 323 mAh g⁻¹ at 0.5 A g⁻¹, along with excellent capacity retention capability. Assembled with a commercial Zn anode, the NiCoS_x/NF//Zn full battery delivers 124 mAh g⁻¹ at 3 A g⁻¹, and maintains 112.5% of the initial capacity after 500 cyclic tests. Moreover, the assembled NiCoS_x/NF//Zn full cell possesses a high energy density of 615.2 Wh kg⁻¹ along with a power density of 38.6 kW kg⁻¹ (based on the mass of positive electrode active materials). This unique vertical 2D open hierarchical structure plays a crucial role in enhancing the electrochemical performance of cobalt sulfide cathodes and provides valuable insights for the design of high-performance alkaline zinc-based battery electrodes. Full article

Biomass-derived carbons are promising sustainable anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because biomass is renewable, abundant, low-cost, and naturally diverse in composition and morphology. Lignocellulosic frameworks, intrinsic heteroatoms, and biomass-derived inorganic species can be converted through carbonization, activation, graphitization, and doping into carbon architectures with tunable porosity, carbon ordering, and surface chemistry. This review first summarizes the compositional and structural features of biomass precursors and explains how processing conditions convert them into carbon frameworks. Recent advances in biomass-derived carbon anodes are then discussed by comparing the distinct design requirements for LIBs and SIBs. For LIBs, accessible surface area, hierarchical porosity, heteroatom-derived active sites, and improved electronic conductivity are generally beneficial for enhancing Li⁺ storage and rate capability. In contrast, SIB hard carbons require controlled surface exposure, expanded turbostratic spacing, and closed or latent pores to improve Na⁺ storage reversibility and initial Coulombic efficiency. These comparisons emphasize that biomass-derived carbon anodes should be designed according to system-specific storage mechanisms rather than a universal carbon design strategy. Full article

Lithium-ion batteries with high energy density and long cycle life have been widely used as secondary batteries in electric vehicles and energy storage systems. With the growing demand for high energy density in lithium-ion batteries, silicon-based materials, which possess a high theoretical specific capacity (4200 mAh g⁻¹), are regarded as core candidates for anode materials. However, Si-based materials undergo severe volume expansion (up to 300%), which leads to the collapse of the electrode structure, inducing pulverization of the active material and capacity loss, thereby hindering the commercial application of silicon-based materials. To address these issues, scholars from various countries have developed many silicon-based materials with different compositions and three-dimensional structures, and have made some research progress. This review first elaborates on the lithium storage mechanisms and advantages of diverse silicon-based anode materials by taking Si, SiO_x, SiN_x, and SiP_x as representative examples with distinct characteristics. Subsequently, from the two aspects of dimensional design (0D, 1D, 2D and 3D) and architecture design (core–shell, sandwich-like and network structure), the design strategies for various silicon-based anode structures and their enhancement on electrochemical performance are analyzed. Finally, this review elucidated the challenges faced by silicon-based anodes from the perspectives of mechanism elucidation, structural customization, industrialization, and full-cell applications. It also proposed future development directions for silicon anodes by combining actual challenges and focusing on aspects such as structure optimization, machine learning, advanced characterization techniques, and mechanistic analysis. Full article

The development of efficient catalysts for the glycerol oxidation reaction (GOR) is crucial for advancing direct glycerol fuel cells. This study provides mechanistic insights into the glycerol electro-oxidation reaction (GOR) on Co@Pt/C, Ni@Pt/C, and Sn@Pt/C catalysts using in situ FTIR spectroscopy. While the structural and electrochemical properties of these materials have been previously reported, their reaction pathways and product selectivity under alkaline conditions remain unclear. Electrochemical performance was evaluated through cyclic voltammetry (CV) and chronoamperometry (1.0 M KOH + 1.0 M glycerol), revealing that the bimetallic catalysts exhibited superior catalytic activity compared to Pt/C. Co@Pt/C demonstrated the highest performance, with a 7.5-fold increase in current density relative to Pt/C, followed by Sn@Pt/C (3.4-fold) and Ni@Pt/C (2.8-fold). In situ FTIR analysis identified key oxidation products, including C3, C2, and C1 species, with evidence of both partial and complete oxidation. These findings demonstrate that the core metal plays a key role in governing reaction pathways and C–C bond cleavage, providing important insights for the rational design of anode materials in direct glycerol fuel cells. Full article

High-nickel NCA/Si–C 21700 cells exhibit strongly condition-dependent degradation, but the coupled influence of temperature and rate on electrochemical, thermal, and structural evolution remains insufficiently resolved. Here, Samsung INR21700-50E cells were aged under a 3 × 3 matrix of ambient temperatures (0, 23, and 40 °C) and C-rates (0.5C, 1C, and 2C). Periodic reference performance tests were used to track capacity, 10 s direct-current internal resistance, electrochemical impedance, pseudo-open-circuit voltage, differential voltage/incremental capacity behavior, heat generation, and post-mortem morphology. Guided by the hypothesis that temperature and rate history change not only the speed but also the dominant pathway of aging, the results show that both ambient temperature and the charge/discharge rate program govern the aging trajectory. Low-temperature cycling accelerates capacity loss and resistance growth through severe polarization and lithium plating, indicating dominant loss of lithium inventory. High-temperature operation promotes interfacial side reactions, impedance rise, and cathode structural degradation, leading to stronger loss of active material at later stages. An increasing C-rate amplifies these effects by raising overpotential and thermal load. Heat generation power increases markedly with aging and depends strongly on temperature–rate history. Scanning electron microscopy confirms cathode cracking, anode surface film thickening, and separator degradation under severe conditions. These experimental indicators are integrated into a mechanism-aware diagnostic framework that maps capacity retention, DCIR/EIS parameters, ICA/DVA indices, and heat generation metrics to dominant aging modes, supporting BMS state-of-health estimation, lifetime prediction, thermal management, and second-life screening of high-nickel NCA cells. The condition-averaged trajectories are further converted into a semi-empirical aging law that links capacity loss, resistance growth, and heat generation increase for BMS-oriented lifetime prediction. Full article

Driven by the “Dual Carbon” goals, supercapacitors have become critical energy storage devices for new energy electric vehicles. In this paper, a ZnFe₂O₄@ZnCo₂O₄ core–shell cathode was prepared by a hydrothermal method followed by high-temperature annealing, and an AC@PANI composite anode was synthesized through in situ polymerization. The materials were characterized by SEM, TEM, XRD, XPS, nitrogen adsorption–desorption and electrochemical tests. The ZnFe₂O₄ rod-like core provides mechanical stability, whereas the ZnCo₂O₄ nanosheet shell increases the specific surface area and exposes more active sites. The cathode delivers 2133 F/g at 1 A/g with 94.4% retention after 10,000 cycles. The anode reaches 398 F/g at 1 A/g. The cathode delivers 2133 F/g at 1 A/g with 94.4% retention after 10,000 cycles. The anode reaches 398 F/g at 1 A/g. The assembled ZnFe₂O₄@ZnCo₂O₄//AC@PANI hybrid supercapacitor works in a wide voltage range of 0–1.6 V. It exhibits a specific capacitance of 157 F/g at 1 A/g and a high energy density of 54.7 Wh/kg at a power density of 1600 W/kg. The device retains 91.4% of its initial capacity after 10,000 charge–discharge cycles. This study offers a promising strategy for high-performance automotive supercapacitors. Full article

Magnetic materials have demonstrated considerable potential for applications in the field of energy storage. Spinel-type CoFe₂O₄ possesses both good redox activity and structural stability, but its magnetism may affect the electrochemical performance. During the high-temperature carbonization and activation processes, the magnetism is significantly weakened, thereby exerting only a limited effect on device performance. To address the issues of high cost and poor environmental friendliness of traditional electrode materials, two types of waste biomass, namely banana peels and sunflower seed shells, were employed as carbon sources for the preparation of Y-doped CoFe₂O₄/carbon composites in this study. Y-doped CoFe₂O₄/banana peel carbon was used as the positive electrode, while Y-doped CoFe₂O₄/sunflower seed shell carbon was used as the negative electrode. The results indicate that the CoFe₂O₄/BPC cathode doped with 0.4% Y has the best performance, with a specific capacitance of 1788 F/g at 1 A/g and a retention rate of 98% after 10,000 cycles. In addition, the SSPC anode exhibited a specific capacitance of 350 F/g and excellent cycling stability. The assembled device achieved a specific capacitance of 190 F/g at 1 A/g and a capacitance retention rate of 83.6% after 10,000 cycles at 5 A/g, demonstrating good energy density, power density and cycling stability. This research provides experimental evidence for the development of low-cost supercapacitors based on biomass. Full article