Search Results (501)

The efficient on-demand generation of ClO₂ is critical for disinfection and food preservation. However, the development of safe and efficient strategies for gaseous ClO₂ production remains challenging. Herein, we report a stable and efficient electrochemical system for ClO₂ production based on rutile TiO₂ nanorod arrays (TiO₂ NAs). Electrochemical optimization suggests that a cathodic potential of −0.10 V (vs. Ag/AgCl) in an electrolyte solution of 1 M NaClO₃ with 5 M H₂SO₄ achieves the highest ClO₂ production efficiency. Mechanistic studies reveal that ClO₂ generation proceeds via an O₂-induced pathway, in which electrochemically generated H₂O₂ from 2-e⁻ O₂ reduction reacts in situ with ClO₃⁻ to form ClO₂, eliminating the need for external H₂O₂ storage and significantly improving operational safety. Furthermore, when decorated with RuO_x nanoparticles, TiO₂ NA cathodes achieve enhanced catalytic performance and excellent stability. In addition, the generated ClO₂ in the electrolyte solution can be delivered via gas pumping. This ClO₂ atmosphere exhibits antibacterial efficiencies exceeding 99% against Escherichia coli and Staphylococcus aureus, and significantly reduced weight loss and preserved fruit hardness in longan samples during 8 days of storage. Overall, this work presents a safe, efficient approach for ClO₂ generation with strong potential for practical disinfection in the food preservation field. Full article

Layered sodium transition-metal oxides are promising cathode materials for sodium-ion batteries due to their high theoretical capacity; however, their practical application is often limited by sluggish Na⁺ diffusion kinetics and structural instability during cycling. P2/O3 phase coexistence has been proposed as an effective strategy to balance capacity and stability, yet it is typically achieved through precise Na-content tuning or complex synthesis conditions, which restrict compositional flexibility. Herein, we demonstrate a phase-engineering approach that induces stable P2/O3 phase coexistence without adjusting the overall Na stoichiometry by controlling the dopant incorporation pathway. Using Na_0.8(Ni_0.25Fe_0.33Mn_0.33Cu_0.07)O₂ (NaNFMC) as a model system, Mg doping via a wet chemical route enables homogeneous dopant distribution, which triggers local stacking rearrangement and the formation of prismatic Na⁺ diffusion channels characteristic of the P2 phase. In contrast, dry-doped samples with identical Mg content retain a predominantly O3-type structure, highlighting the decisive role of dopant incorporation in governing phase evolution. As a result of the phase-engineered P2/O3 coexisting framework, the Mg wet-doped cathode exhibits enhanced initial reversibility, superior rate capability, and improved long-term cycling stability compared to pristine and dry-doped counterparts. Voltage-resolved dQ/dV and cyclic voltammetry analyses reveal stabilized redox behavior with reduced polarization, while electrochemical impedance spectroscopy confirms suppressed impedance growth and improved Na⁺ transport kinetics after cycling. This study establishes that phase engineering through controlled dopant incorporation provides an effective alternative to conventional Na-content tuning strategies for layered sodium cathodes. The findings offer a scalable and versatile design principle for optimizing the electrochemical performance and structural durability of next-generation sodium-ion battery cathode materials. Full article

Lithium metal batteries (LMBs) have been widely studied due to their high energy density; however, the practical implementation of LMBs is limited by issues of uncontrolled dendrite growth, continuous electrolyte decomposition, and poor Coulombic efficiency (CE). Highly concentrated electrolytes (HCEs) have emerged as a promising approach to addressing the above issues. In this work, we propose a new HCE system based on a single carbonate solvent of 2,2,2-trifluoroethyl methyl carbonate (FEMC) with a high concentration of lithium bis(fluorosulfonyl)imide (LiFSI). The resulting electrolytes exhibit enhanced anodic stability and improved compatibility with lithium metal anodes and high-voltage cathodes. The optimized 4 M LiFSI–FEMC HCE achieved the highest CE for Li plating/stripping in Li/Cu cell and lowest overpotential in Li/Li symmetric cells, outperforming both low-concentration FEMC and ethyl methyl carbonate (EMC)-based electrolytes. In full-cell configurations with LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathodes, the HCE demonstrates stable cycling with minimal capacity fade over 250 cycles. Importantly, the HCE enables stable operation of 4.6 V high-voltage NCM811/Li cells for more than 120 cycles with a high-capacity retention of 88.61%. Post-mortem analysis revealed a more uniform and compact solid electrolyte interphase and a thinner cathode electrolyte interphase, contributing to the enhanced cycling performance. Full article

Both Co-free and lithium- and manganese-rich layered oxide Li(Li_0.2Mn_xNi_yFe_z)O₂ (MNF) cathodes have recently attracted attention in lithium-ion battery (LIB) research due to their high capacities of over 250 mAhg⁻¹, as well as being more eco-friendly and inexpensive than commercial NMC and LiCoO₂. However, they still suffer from lower experimental capacity as well as capacity decay, voltage fade, poor rate capability, and thermal instability. In this paper, fluorine (F)-doped Li_1.2(Mn_0.5Ni_0.2Fe_0.1)O_2(1−x)F_2x (MNF502010, x = 0, 0.025, 0.05, 0.075, 0.1) cathode materials have been synthesized in the nanoscale via sol–gel and subsequent solid-phase calcination to address some of these problems. The resulting 5% F-doped MNF502010 cathode demonstrates the advantage of fluorine doping, which makes a significant contribution to the formation of a well-ordered layer structure with a minimal LiM₂O₄ spinel phase as an impurity. This composition achieves an initial discharge capacity of 252 mAhg⁻¹ (1C = 250 mAhg⁻¹) and a 156 mAhg⁻¹ discharge capacity at 0.3 C on the 100th discharge, with an average voltage fade of 0.24 V. The optimization of fluorine composition results in an enhancement in the activation of the Li₂MnO₃-type monoclinic phase, as well as an increase in the electronic conductivity compared to the fluorine-free cathode. To understand the structural origin of this improved performance, X-ray absorption spectroscopy (XAS) measurements were carried out on pristine and cycled MNF electrodes. Full article

Although halide solid electrolytes (HSEs) demonstrate a higher voltage window and superior interfacial stability toward Li-rich layered oxides (LLOs) compared to sulfide systems, HSE-based all-solid-state lithium batteries (HSE-ASSLBs) still face a fundamental trade-off between achieving high capacity and maintaining cycling stability. To resolve this issue, a rational adjustment of the depth-of-discharge (DOD) via discharge cut-off voltage control is proposed. Analysis of dQ/dV profiles and post-cycled electrodes indicates that excessive DOD (lower cut-off voltages) aggravates structural degradation and interfacial side reactions, whereas insufficient DOD (higher cut-off voltage) fails to fully utilize the compensatory capacity from low-voltage redox couples. Notably, an optimized cut-off voltage of 2.6 V activates a stable low-voltage redox reaction centered around 2.85 V, which effectively offsets high-voltage capacity loss while suppressing unfavorable interfacial evolution. As a result, the ASSLB configured with a Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ cathode and a Li_2.75In_0.75Zr_0.25Cl₆ HSE delivers an initial discharge capacity of 281.6 mAh g⁻¹ at 1C and achieves significantly improved capacity retention from 71.8% to 86.1% over 300 cycles. This study confirms that DOD regulation offers a simple and effective electrochemical protocol for enabling durable high-capacity output in LLO-based ASSLBs. Full article

Nd₂NiO_4+δ was investigated as a Ruddlesden–Popper (RP) cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs), with particular emphasis on its electrochemical performance and oxygen reduction reaction mechanism. The material was synthesized via a polymeric sol–gel route derived from Pechini’s method and evaluated in symmetric cells using Ce_0.9Gd_0.1O_2−δ (GDC) as the electrolyte. X-ray diffraction confirmed the formation of a single RP phase and good chemical compatibility with GDC after thermal treatments at 800 °C. Cathode layers with thicknesses of 8–12 µm were deposited by dip-coating. Electrical conductivity measurements revealed a thermally activated semiconducting behavior governed by Ni²⁺/Ni³⁺ small-polaron hopping, with an activation energy of ~1.08 eV. Electrochemical impedance spectroscopy showed a strong temperature dependence of the area-specific resistance, decreasing from 9.18 Ω·cm² at 600 °C to 0.39 Ω·cm² at 800 °C. Distribution of relaxation times (DRT) analysis enabled the identification of the dominant electrochemical processes, indicating that oxygen surface exchange reactions are more favorable than charge transfer at the cathode–electrolyte interface, which remains the main limiting step. These results demonstrate that Nd₂NiO_4+δ is a promising cathode for IT-SOFC operation, while further optimization of the electrode–electrolyte interface is required to enhance its oxygen reduction kinetics. Full article

The demand for high-energy-density and fast-charging solid-state lithium metal batteries (SSLMBs) often subjects practical devices to internal thermal loads, making high-temperature operation a common operational condition rather than an isolated scenario. To address the interfacial degradation and dendrite growth accelerated by such thermomechanical stresses, we developed a composite gel electrolyte (CGE) by incorporating an optimal concentration of active Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) into a fluoropolymer network. The abundant Lewis acidic sites on the LLZTO surfaces promote competitive solvation decoupling by interacting with anions, thereby modulating the primary solvation sheath of Li⁺. This localized modulation lowers the lithium-ion migration activation energy to 0.248 eV and facilitates a dual-interfacial passivation mechanism. Specifically, a rigid, inorganic-rich solid electrolyte interphase (SEI) forms to suppress morphological instability at the lithium anode, while an organic-dominated cathode electrolyte interphase (CEI) enhances the oxidative stability up to 4.3 V. As a result, symmetric cells demonstrate stable electrodeposition for over 450 h at 80 °C and 0.5 mA cm⁻². Furthermore, NCM811/Li full cells utilizing this CGEs exhibit significantly improved thermal resilience and cycling stability. Full article

To meet the requirements of flexibility and high performance for energy storage devices in flexible wearable electronic equipment, the MnO₂/acetylene black composite flexible cathodes is fabricated via 3D printing technology and the aqueous manganese-based zinc-ion flexible batteries are assembled. Based on bending and torsion mechanical tests, and the electrochemical tests, the optimal 3D printing electrode structure was determined. The micromorphology of the electrode after mechanical tests shows that when the printed lines of the upper and lower layers form a 30° angle, the electrode sheet exhibits the least damage. Electrochemical tests indicated that it had an ohmic resistance of 2.052 Ω, an interfacial charge transfer resistance of 141.1 Ω, a specific capacity of 103 mAh/g at 50 mA/g, and a specific capacity of 65 mAh/g at 500 mA/g. Compared with traditional coated electrodes, the 3D-printed electrode showed significantly improved diffusion coefficient, conductivity, and cycle stability. The assembled 3D-printed flexible battery could stably power a 1.5 V LED bulb under flat, bent, and twisted states. It provides a feasible solution for the development of high-performance flexible energy storage devices. Full article

Layered nickel-rich cathodes are regarded as promising cathode materials for lithium-ion batteries (LIBs) due to their higher electrochemical capacities and lower cost. However, the development and commercial application of nickel-rich cathodes are severely hindered by significant capacity fading under a high charge cut-off voltage (4.5 V), which arises from interfacial instability and bulk structural degradation during charge–discharge processes. In this study, a two-step double-coating strategy was innovatively adopted to successfully synthesize Al₂O₃/LiBO₂ co-coated LiNi_0.71Co_0.09Mn_0.2O₂ cathode material (denoted as NCM-Al/B). X-ray photoelectron spectroscopy (XPS) verified that Al existed stably in the form of Al³⁺, and B formed B-O-M covalent bonds with transition metals (Ni/Co/Mn), constructing a dual-element synergistic interface. This interface significantly reduced the surface Ni³⁺ content and enhanced the structural stability by suppressing the H₂→H₃ phase transition. The NCM-Al/B material exhibits excellent electrochemical performance: it maintains a remarkable cycling stability with a capacity retention of 91.6% after 100 cycles at 1 C and 25 °C and delivers a discharge capacity of 156.6 mAh·g⁻¹ with a capacity retention of 75.4% after 100 cycles at a high rate of 1 C. This work establishes a chemically driven double-coating strategy and provides a new paradigm for optimizing the performance of high-nickel cathode materials. 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

Gel polymer electrolytes (GPEs) typically suffer from sluggish kinetics and interfacial instability at elevated temperatures and high voltages. Herein, 3-(trifluoromethyl)-1H-1,2,4-triazole (TTA) is employed to construct an ultrathin (~25 μm), robust, and homogeneous GPE. TTA acts as a molecular bridge, significantly improving compatibility between the PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene)) matrix and LLZTO (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) fillers to create continuous ion-conducting pathways. Consequently, the TTA-GPEs exhibits high ionic conductivity (0.267 mS cm⁻¹ at room temperature), low activation energy (0.181 eV), and an increased lithium-ion transference number (0.425). Advanced surface analysis reveals that TTA preferentially reacts to form a dense, gradient hierarchical interphase (solid electrolyte interphase/cathode electrolyte interphase, SEI/CEI) enriched with inorganic species (LiF, Li₃N, and Li₂S) on the inner side. This architecture suppresses parasitic reactions and lithium dendrite growth. Accordingly, NCM811(LiNi_0.8Co_0.1Mn_0.1O₂)//Li batteries with TTA-GPEs demonstrate stable cycling at 80 °C and 1C, retaining 57.68% capacity after 125 cycles—significantly outperforming benchmarks. This study offers a molecular engineering strategy to simultaneously optimize bulk transport and interfacial stability for high-energy-density solid-state batteries. Full article

Polymer electrolytes have been explored as an alternative to conventional aqueous electrolytes in zinc-ion batteries, particularly for flexible and wearable applications. Despite the increasing interest in polymer electrolyte-based zinc-ion batteries (ZIBs), their development is still in its early stages due to various challenges. In this study, we investigated three promising polymer electrolytes: CSAM (carboxyl methyl chitosan with acrylamide monomer), PAM (polyacrylamide monomer hydrogel electrolyte), and p-PBI (phosphate-doped polybenzimidazole solid electrolyte) with Zn(ClO₄)₂ and Zn(OTf)₂, as electrolytes for zinc-ion batteries. The p-PBI solid electrolyte showed high mechanical stability and improved resistance to short-circuiting during cycling. The presence of carboxyl groups in CSAM and the existence of O-H bonding facilitated ion movement, resulting in enhanced ionic conductivity and preventing dendrite formation. Incorporating these hydrogels with high-performance zinc salts, such as zinc triflate (Zn(OTf)₂), resulted in stable symmetric cell cycling over 4000 h with a uniform voltage profile under 1 mA/cm² and a low overpotential of around 53 mV cycling with CSAM. Rate-dependent full-cell testing showed that the PBI solid electrolyte delivers higher capacity retention at different current densities, whereas CSAM exhibits markedly better long-term stability, even at low voltages, owing to its effective dendrite suppression, which helps preserve cathode performance over extended cycling. 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

In this work, the coordination compound sulfate of aqua{tris(2-pyridylmethyl) amine}zinc(II) ([Zn(TPA)(H₂O)]SO₄) is investigated as a catalyst for the molecular reduction of CO₂. The complex was synthesized and characterized by FT–IR, UV–Vis, TGA, and NMR spectroscopy. Cyclic voltammetry reveals irreversible electrochemical behavior, with two cathodic peaks at E_pc = −1.72 V and E_pc = −1.99 V vs. Fc/Fc⁺, respectively. Under a CO₂ atmosphere, a catalytic wave appears at E_pc = −1.87 V vs. Fc/Fc⁺, indicating catalytic activity toward CO₂ reduction. This behavior was further confirmed by Foot-of-the-Wave Analysis (FOWA), which yielded a catalytic rate constant of (k = 1.352 × 10³ M⁻¹ s⁻¹). Bulk electrolysis experiments combined with FT–IR analysis suggest that format is the main product of the CO₂ reduction catalyzed by [Zn(TPA)(H₂O)]SO₄. Electrochemical impedance spectroscopy was used to examine the catalytic process at the electrode–electrolyte interface. In addition, density functional theory (DFT) calculations were conducted to analyze the interaction between the [Zn(TPA)(H₂O)]SO₄ complex and CO₂. Full article

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are two processes that occur during the operation of the cathodic electrode in Zn–Air batteries, which enable the integration of alternative energy sources into electrical energy distribution systems. Transition metal oxides, such as perovskites based on LaNiO₃, are promising electrocatalysts for the ORR and OER in alkaline medium due to their versatile structure, allowing for the substitution of certain atoms with dopants, which enhances the catalytic activity for both reactions. This work reports an electrochemical study of the catalytic activity toward ORR and OER of perovskite catalysts (LaNiO3 doped with transition metals (Fe, Mn, or Pd)) in the presence of carbon-based materials as supports (multiwalled carbon nanotubes (MWCNT), graphene oxide nanosheets (GO), and graphitic carbon (C)). The results revealed interesting catalytic properties in both reactions, particularly La(Ni_0.9Pd_0.1)O₃/MWCNT, which showed an ORR activation potential of 0.87 V vs. RHE, comparable to that of the commercial Pt/C catalyst (0.99 V vs. RHE), while the overpotential for OER was lower than that of the Pt/C catalyst (1.68 V vs. RHE for La(Ni_0.9Pd_0.1)O₃/MWCNT and 1.79 V vs. RHE for the commercial Pt/C). Full article