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Organic‐metal coordination materials with rich structural diversity are considered as promising electrode materials for rechargeable sodium‐ion batteries. However, the electrochemical performance can be constrained by the limited number of active sites and structural instability under the discharge/charge process. Herein, organometallic polymer microspheres (Fe‐PDA‐220) with a unique d‐π conjugated structure was designed and successfully constructed through a simple synchronous polymerization and coordination reactions. Polymerization of phenylenediamine was initiated by Fe3+ and Fe2+ ions generated synchronously during the polymerization integrated with poly‐aminoquinone chains to form Fe−C12N8 active centers. Used as electrode materials for sodium‐ion batteries, the distinctive Fe−C bond significantly boosts the structural stability, and the π‐d conjugation system could facilitate electron transfer. A high reversible capacity of 345 mAh g−1 was delivered at 0.1 A g−1 and a capacity of 106 mAh g−1 was maintained even after discharged/charged at 1.0 A g−1 for 5000 cycles, outperforming most reported coordination materials. Spectroscopic and electronic analyses revealed that a two‐electron reaction occurred per active unit, accompanied by the reversible redox evolution of the C=N groups and Fe ions during the sodiation/desodiation. This work provides a promising and efficient strategy for boosting the electrochemical performance of organic electrode materials by the design of organometallic polymers. [ABSTRACT FROM AUTHOR]

With the large-scale application of lithium-ion batteries (LIBs) in various fields, spent LIBs are considered one of the most important secondary resources. Few studies have focused on recycling anode materials despite their high value. Herein, a new efficient recycling and regeneration method of spent anode materials through the combination of thermal and wet metallurgical approaches and restored graphite performance is presented. Using this method, the lithium recycling ratio from spent anode materials reaches 87%, with no metal impurities detected in the leaching solution. The initial Coulombic efficiency of the recycled graphite (RG) materials is 90.5%, with a reversible capacity of 350.2 mAh/g. Moreover, RG shows better rate performance than commercial graphite. The proposed method is simple and efficient and does not involve toxic substances. Thus, it has high economic value and application potential in graphite recycling from spent LIBs. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) are important anode materials in sodium-ion batteries (SIBs) due to their high theoretical capacities, abundant resources, and cost-effectiveness. However, issues such as the low conductivity and large volume variation of TMO bulk materials during the cycling process result in poor electrochemical performance. Nanosizing and compositing with carbon materials are two effective strategies to overcome these issues. In this study, spherical MnFe2O4@xC nanocomposites composed of MnFe2O4 inner cores and tunable carbon shell thicknesses were successfully prepared and utilized as anode materials for SIBs. It was found that the property of the carbon shell plays a crucial role in tuning the electrochemical performance of MnFe2O4@xC nanocomposites and an appropriate carbon shell thickness (content) leads to the optimal battery performance. Thus, compared to MnFe2O4@1C and MnFe2O4@8C, MnFe2O4@4C nanocomposite exhibits optimal electrochemical performance by releasing a reversible specific capacity of around 308 mAh·g−1 at 0.1 A·g−1 with 93% capacity retention after 100 cycles, 250 mAh·g−1 at 1.0 A g−1 with 73% capacity retention after 300 cycles in a half cell, and around 111 mAh·g−1 at 1.0 C when coupled with a Na3V2(PO4)3 (NVP) cathode in a full SIB cell. [ABSTRACT FROM AUTHOR]

Constantly striving to develop a facile and scalable way to construct advanced electrodes is essential for the advancement of batteries and electrocatalysis. In this work, an artful K 2 FeO 4 oxidation cooperated with subsequent annealing process is proposed to produce 3D FeS embedded into N, S co–doped carbon nanotube/graphene (FeS/NSCNT/NSG) framework, which simultaneously achieves successful exfoliation of graphite, effective N, S co–doping and desirable integration of 3D framework by FeS and carbon matrix. The adopted procedure is simple, rapid and recyclable. Furthermore, the obtained FeS/NSCNT/NSG exhibits a unique 3D architecture, high doping level and favorable FeS dispersion status, thus displaying excellent performance towards lithium–ion batteries and oxygen evolution reaction. Undoubtedly, our research opens a new pathway for the development of advanced electrodes for energy storage and conversion devices. An artful K 2 FeO 4 oxidation assisted strategy can be used to produce 3D FeS/NSCNT/NSG framework, which realizes successful exfoliation of graphite, effective N, S co–doping and delicate assembly of multiple components, thus exhibiting good performance towards lithium–ion batteries and oxygen evolution reaction. [Display omitted] • An artful K 2 FeO 4 oxidation assisted strategy was proposed to produce 3D FeS/NSCNT/NSG. • The K 2 FeO 4 oxidation method is very simple, rapid and recyclable. • The adopted method achieves the goal of "one–stone–three–birds. • FeS/NSCNT/NSG shows unique 3D architecture and favorable FeS dispersion status. • FeS/NSCNT/NSG displays promising application towards LIBs and OER. [ABSTRACT FROM AUTHOR]

Structural property is becoming a powerful tool to manipulate oxygen vacancy concentration and electrochemical performance of electrode material. In this work, the structure-electrochemical performance relationship of Sr 2 (Fe 1-x V x)MoO 6 (x = 0, 0.1, 0.2 and 0.25) anode is investigated based on X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Energy Dispersive Spectrometer (EDS), BET surface area, DC four-point probe, I–V and electrochemical impedance spectra (EIS). XRD results show that all the compounds are of single phase, the tetragonal to cubic phase transition occurs at x = 0.1, which plays important role in its electrochemical performance. Firstly, the disappeared structural distortion in Sr 2 (Fe 1.8 V 0.2)MoO 6 and Sr 2 (Fe 1.75 V 0.25)MoO 6 anodes benefits electron hopping between Fe–O–Mo–O–Fe, so electron transfer processes (high-frequency semicircle) in their EIS are facilitated. Secondly, both XPS survey and EDS spectrum confirm the change in oxygen content with structural transition, Sr 2 (Fe 1.9 V 0.1)MoO 6 anode own higher concentration of oxygen vacancy, thus the oxygen surface exchange and diffusion process (low-frequency arc) of the corresponding cell is reduced significantly. Consequently, Sr 2 (Fe 1.9 V 0.1)MoO 6 -based cell exhibits the highest power output (810 mW cm−2) at 850 °C. For Sr 2 (Fe 1.8 V 0.2)MoO 6 anode, BET surface area test reveals the slightly higher value, while its lower power density indicates that the influence of oxygen vacancy prevails over that of microstructure. Combining with EIS results, it can be deduced that Sr 2 (Fe 1-x V x)MoO 6 anodes with tetragonal symmetry own higher concentration of oxygen vacancy, thus the expected electrochemical performance is better than that of other cells. Understanding the critical role of structure is important for achieving highly active electrode material. • Electrochemical performance of Sr 2 (Fe 1-x V x)MoO 6 changes significantly with structural transition. • Conductivity of Sr 2 (Fe 0.9 V 0.1)MoO 6 is enhanced significantly by V doping. • Sr 2 (Fe 0.9 V 0.1)MoO 6 anode depicts the best electrochemical performance. [ABSTRACT FROM AUTHOR]

Recently, supercapacitors (SCs) have emerged as one of the most promising energy storage devices, which can be attributed to their exceptional power density, rapid charge–discharge rate, and superior cycling stability. Despite the progress made in the signal metal oxide of SCs, several challenges still need to be addressed, including the poor electrical conductivity, unsatisfactory cyclic stability, and low energy density. It is crucial to develop innovative composite materials with synergistic effects to address these issues. In this study, the cobalt oxide and Co3O4@NiCo2O4 composite were successfully synthesized on Ni foams by a hydrothermal method. Composite electrodes featured by the hierarchical core–shell structures were identified as an effective approach for improving the electrochemical performance of SCs. Noteworthily, the as-fabricated core–shell structures demonstrated excellent specific capacitance of 1514 F g−1 at a current density of 1 A g−1, a stable operating voltage of 0–0.5 V and outstanding cycling stability (with almost no attenuation after 2000 cycles at a charge–discharge current density of 10 A g−1). The enhanced electrochemical behavior can be attributed to the synergistic effect between two electrode active materials and the presence of more electron and ion transport pathways. The as-prepared composite electrodes can be considered as the potential electrode materials for energy storage applications. [ABSTRACT FROM AUTHOR]

To mitigate the greenhouse effect and environmental pollution caused by the consumption of fossil fuels, recent research has focused on developing renewable energy sources and new high-efficiency, environmentally friendly energy storage technologies. Among these, Li–CO2 batteries have shown great potential due to their high energy density, long discharge plateau, and environmental friendliness, offering a promising solution for achieving carbon neutrality while advancing energy storage devices. However, the slow kinetics of the CO2 reduction reaction and the accumulation of Li2CO3 discharge on the cathode surface lead to a significant reduction in space and active sites. This in turn results in high discharge overpotential, low energy efficiency, and low power density. This study elucidates the charge–discharge reaction mechanisms of lithium–carbon dioxide batteries and systematically analyzes their reaction products. It also summarizes the latest research advancements in cathode materials for these batteries. Furthermore, it proposes future directions and efforts for the development of Li–CO2 batteries. [ABSTRACT FROM AUTHOR]

Alkali metals (Li, Na, and K) are deemed as the ideal anode materials for next-generation high-energy-density batteries because of their high theoretical specific capacity and low redox potentials. However, alkali metal anodes (AMAs) still face some challenges hindering their further applications, including uncontrollable dendrite growth and unstable solid electrolyte interphase during cycling, resulting in low Coulombic efficiency and inferior cycling performance. In this regard, designing 3D current collectors as hosts for AMAs is one of the most effective ways to address the above-mentioned problems, because their sufficient space could accommodate AMAs' volume expansion, and their high specific surface area could lower the local current density, leading to the uniform deposition of alkali metals. Herein, we review recent progress on the application of 3D Cu-based current collectors in stable and dendrite-free AMAs. The most widely used modification methods of 3D Cu-based current collectors are summarized. Furthermore, the relationships among methods of modification, structure and composition, and the electrochemical properties of AMAs using Cu-based current collectors, are systematically discussed. Finally, the challenges and prospects for future study and applications of Cu-based current collectors in high-performance alkali metal batteries are proposed. [ABSTRACT FROM AUTHOR]

In this work, Mn2P2O7 nanoparticles were synthesized via hydrothermal route without any templates or surfactants followed by heat treatment at 700 ∘ C. The as-prepared samples were characterized and described using thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Scanning electron microscopy (SEM) analysis. The resultant product was evaluated for electrochemical properties in organic electrolyte between −1.4 and 1.6 V using cyclic voltammetry in ambient condition. It revealed the specific capacitance of 565 F/g at scan rate of 5 mV/s. The outstanding pseudocapacitive performance was absorbed due to the faradaic oxidation and reduction reactions related to the intercalation/de-intercalation of the tetrabutylammonium cation (TBA +) electrolyte and inorganic pyrophosphate lattice. It was believed that the cost effective Mn2P2O7 nanoparticles may be promising electrode materials for electrochemical capacitors. [ABSTRACT FROM AUTHOR]

The study reports the synthesis of conductive MOFs (Metal-organic frameworks) of the type NBu4M(DHBQ)1.5 (M = Ni2+, Cu2+, and Co2+; DHBQ = 2,5- dihydroxy-1,4-benzoquinone) and their subsequent incorporation in PVP-based electrospun mats (EMs). The MOFs and MOF-modified EMs were carbonized to fabricate nanostructured metal oxide/carbon nanomaterial (MO/CNM). The synthesized and carbonized MOFs (MO/CNMs) and MOF-modified PVP EMs (MO/CNM EMs) were subjected to morphological, microstructural, and electrochemical characterization. Morphological analysis indicated a more uniform dispersion of networked nanomaterial on carbonization of MO/CNM EMs than MO/CNMs. Microstructural analysis revealed the successful formation of MOFs using metallic salts and DHBQ and the subsequent incorporation of MOFs in PVP-based EMs. Raman spectra and energy-dispersive X-ray spectra (EDX) also indicated the presence of corresponding metal oxide in the respective MO/CNMs and MO/CNM EMs. However, MOF-Cu-loaded PVP-based EMs could not be fabricated due to the limited dispersion of whisker-like Cu-MOF in PVP-based precursor solution resulting in repeated needle clogging. The uniaxial tensile strength of PVP-based EMs was observed to deteriorate with MOF loading, however, MOF-Ni exhibited comparatively higher elongation-at-break (~ 12%) than PVP-based EMs. Further, electrochemical characterization indicated MOF-Ni and MOF-Ni EM-based electrodes to exhibit comparatively better electrochemical performance than respective MOF-Co and MOF-Cu-based electrodes. Therefore, the study demonstrates the synthesis and development of uniformly dispersed metal oxide-based carbon nanomaterial using PVP-based EMs for designing engineered nanostructured materials for targeted drug delivery, sensor, and energy storage applications. [ABSTRACT FROM AUTHOR]

Novel MnCo 2 O 4 -discs and MnCo 2 O 4 -rings were respectively prepared through a facile hydrothermal approach with a post annealing treatment. These MnCo 2 O 4 -discs exhibited battery-type electrochemical response with a high capacity of 296.1C/g at 1 A/g in 2 M of KOH electrolyte. The assembled MnCo 2 O 4 -discs//AC asymmetric supercapacitor delivered a high energy density of 35.8 W h kg−1 at the power density of 927.5 W kg−1. [Display omitted] • Novel MnCo 2 O 4 -discs were hydrothermally prepared with a post annealing treatment. • A high specific capacity of 296.1C/g at 1 A/g was delivered. • Just a little capacity decay over 5000 cycles at a high current density of 6 A/g. • The ASC device delivered an energy density of 35.8 W h kg−1 at 927.5 W kg−1. Herein, porous MnCo 2 O 4 with disc-like (MnCo 2 O 4 -discs) and ring-like (MnCo 2 O 4 -rings) microstructures were respectively synthesized using an initial hydrothermal method at different temperatures and a calcination treatment in air. The electrochemical properties of these MnCo 2 O 4 materials were investigated in three-electrode and two-electrode systems, and as such, MnCo 2 O 4 presented a battery-like electrochemical response. The specific capacity of MnCo 2 O 4 -discs was determined to be 296.1C/g at 1 A/g, superior to 246.3C/g for MnCo 2 O 4 -rings. An asymmetric supercapacitor (ASC) was assembled with MnCo 2 O 4 as the cathode and activated carbon (AC) as the anode to evaluate the potential for practical application. The MnCo 2 O 4 -discs//AC ASC exhibited an energy density (E d) of 35.8 W h kg−1 at a power density (P d) of 927.5 W kg−1. For the MnCo 2 O 4 -rings//AC ASC, an inferior E d of 31.4 W h kg−1 under 890.9 W kg−1 was achieved. Furthermore, the two ASCs presented outstanding cyclic performance after 5000 cycles at 6 A/g. The exceptional properties of MnCo 2 O 4 microstructures can be applied to the assembly of ASC devices, which can have promising potential for application in electrochemical energy storage. This synthetic method is straightforward, cost-effective, and can be extended to fabricate similar electrode materials with superior electrochemical performance. [ABSTRACT FROM AUTHOR]

Zinc manganese oxide (ZnMn2O4), exhibiting a clustered spherical structure, is synthesized using a low-temperature coprecipitation method. Following this, a coating of nano-sized Al2O3 is applied via a wet chemical technique. The resultant materials—designated as ZnMn2O4 (ZMO) and Al2O3—coated ZnMn2O4 (ZMO-AlO)-undergo characterization using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Scanning electron microscopy reveals that both ZMO and ZMO-AlO retain their clustered spherical morphologies. Furthermore, XPS and TEM confirm the presence of an Al2O3 layer on the ZMO-AlO sample. In terms of electrochemical performance, a significant improvement is observed. Specifically, the Al2O3 coating enhances the initial discharge capacity of ZMO-AlO to 1228 mAh·g−1, compared to the 1140 mAh·g−1 capacity of the unmodified ZMO material. During the second charging and discharging cycle, the ZMO-AlO samples demonstrate specific capacities of 763 and 788 mAh·g−1, respectively, achieving a coulombic efficiency of 96.8%. By contrast, the ZMO samples show specific capacities of 760 and 715 mAh·g−1, respectively, with a slightly lower coulombic efficiency of 94.1%. When evaluating the electrochemical lithium storage performance of ZMO and ZMO-AlO at a current density of 100 mA·g−1, it becomes evident that the Al2O3-modified ZnMn2O4 (ZMO-AlO) offers superior performance compared to the unmodified ZMO. [ABSTRACT FROM AUTHOR]

Layered high nickel LiNi0.8Co0.15Al0.05O2 (NCA), as one of the most promising cathode materials in lithium-ion batteries, has high specific capacity, stable structure, and environmentally friendly characteristics. However, severe Li+/Ni2+ mixing and surface side reactions hinder its further development. To solve these issues, fast lithium-ion conductor LiTi2(PO4)3 was coated on the surface of NCA using wet chemistry and high-temperature solid-state methods. The LiTi2(PO4)3 coating not only reduces the Li+/Ni2+ mixing effect of NCA, but also effectively suppresses the side reactions between the electrolyte and NCA surface, thereby improving its cycling performance. After 200 cycles at 1C, the capacity retention rate of pure NCA is 72.1%, while the corresponding value of 2.0wt% LTP-NCA is 88.0%. Even at a high rate of 5C, due to high Li+ diffusion rate of LiTi2(PO4)3, the capacity of 2.0wt% LTP-NCA reaches 152.8 mAh g−1 compared to 136.2 mAh g−1 of pure NCA. Therefore, fast lithium-ion conductor coating modification effectively improves electrochemical performance, which is beneficial for the further commercialization of NCA cathode materials. [ABSTRACT FROM AUTHOR]

MnO2@PCs (porous carbons) exhibiting high energy and power density are utilized as supercapacitor electrodes and prepared by impregnating porous carbons (PCs) derived from coal tar pitch (CTP) with KMnO4 as the manganese source. This study systematically investigates the impact of MnO2 loading on the microstructure and electrochemical performance in sample. It is found that the specific surface areas (SSA) of all MnO2@PCs significantly reduced compared to that of the PCs 2789 m2 g−1. The suggested mechanism might be a combination of the energy storage mechanism of dual layer capacitors with pseudo‐capacitance due to redox reactions of MnO2. Notably, MnO2@PCs‐0.0075 exhibits a maximum SSA of 1454.62 m2 g−1. Its specific capacitance reached 561 F g−1 at 0.5 A g−1, while the capacitance of the PCs increased by 81.5% to 309 F g−1. Remarkably, the Coulombic efficiency remained at 100%. The power density and energy density are determined in a two‐electrode test system to be 0.5 kW kg−1 and 58.01 Wh kg−1, respectively, at 0.5 A g−1. Concluding from these results and related literature, the MnO2 content significantly influences the electrochemical performance, suggesting that MnO2@PCs‐0.0075 could be a promising supercapacitor (SC) electrode material, provided its capacitance retention is enhanced. [ABSTRACT FROM AUTHOR]

As a typical spinel structure material, ZnMn2O4 has been widely researched in the field of electrode materials. However, ZnMn2O4 nanoparticles as electrode materials for supercapacitors have the disadvantages of low conductivity, inferior structural integrity, and easy aggregation, resulting in unsatisfying electrochemical performance. In this work, we use a hydrothermal method and high-temperature calcination to deposit ZnMn2O4 nanoparticles on carbon cloth and explore the influence of hydrothermal reaction time on the deposition morphology and distribution of ZnMn2O4 nanoparticles on carbon cloth. The deposition process of ZnMn2O4 nanoparticles on carbon cloth was analyzed, and a ZMO-9 electrode was deduced to be the most suitable electrode for supercapacitors. A series of electrochemical performance tests show that the ZMO-9 electrode has excellent specific capacitance (specific capacity) (499 F·g−1 (299.4 C·g−1) at a current density of 1 A·g−1) and rate performance (75% capacitance retention at a current density of 12 A·g−1). The assembled asymmetric supercapacitor has an energy density of 46.6 Wh·kg−1 when the power density is 800.1 W·kg−1. This work provides a reference for the structural design of ZnMn2O4 supercapacitor electrode materials and the improvement of electrochemical properties. [ABSTRACT FROM AUTHOR]

As modern society continues to advance, the depletion of non-renewable energy sources (such as natural gas and petroleum) exacerbates environmental and energy issues. The development of green, environmentally friendly energy storage and conversion systems is imperative. The energy density of commercial lithium-ion batteries is approaching its theoretical limit, and even so, it struggles to meet the rapidly growing market demand. Lithium–oxygen batteries have garnered significant attention from researchers due to their exceptionally high theoretical energy density. However, challenges such as poor electrolyte stability, short cycle life, low discharge capacity, and high overpotential arise from the sluggish kinetics of the oxygen reduction reaction (ORR) during discharge and the oxygen evolution reaction (OER) during charging. This article elucidates the fundamental principles of lithium–oxygen batteries, analyzes the primary issues currently faced, and summarizes recent research advancements in air cathodes and anodes. Additionally, it proposes future directions and efforts for the development of lithium–air batteries. [ABSTRACT FROM AUTHOR]

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Lithium‐ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway‐caused fires, and intelligent application are obstacles to their applications. Herein, bio‐inspired electrodes owning spatiotemporal management of self‐healing, fast ion transport, fire‐extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self‐healing core–shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation–delithiation cycling. After the incorporation of fire‐extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio‐inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage. [ABSTRACT FROM AUTHOR]

Supercapacitors have emerged as promising electrochemical storage, offering advantages such as rapid charge/discharge rates and environmental friendliness. Nevertheless, their practical applications have been limited due to their lower energy density, and selecting electrode materials with superior energy storage properties remains a critical factor. NiCo2S4 nanomaterials have gained significant attention due to their high theoretical specific capacitance, narrow band gap, and abundant redox reaction active sites, but challenges such as poor cyclic stability and volumetric effects associated with prolonged charging and discharging persist. This paper reviews the recent research progress on NiCo2S4 nanomaterials and comprehensively discusses various strategies to improve the electrochemical performance of NiCo2S4, including morphology control, design and development of NiCo2S4-based composite electrode nanomaterials, doping of different elements, utilization of defect engineering and phase engineering strategies, and exploration of theoretical studies. Finally, the prospects and challenges for the development of NiCo2S4 electrode nanomaterials in the field of supercapacitors are also suggested. [ABSTRACT FROM AUTHOR]

Symmetrical solid oxide fuel cells (SSOFCs) with symmetrical electrodes have many desirable characteristics compared with conventional SOFCs. However, the lack of electrode materials simultaneously satisfied the high electrocatalytic activity in oxidizing and reducing atmospheres. Herein, a novel perovskite oxide electrode (PrBa) x Fe 1.9 Nb 0.1 O 5+δ ((PB)xFN, x = 1, 0.97, 0.95 and 0.93) was reported as a promising symmetrical electrode material for SSOFCs. XRD results reveal that the (PB)0.95FN sample has a tetragonal structure and good chemical compatibility with Gd 0.1 Ce 0.9 O 2-δ electrolyte. Among all the samples, (PB)0.95FN has the lowest polarization resistance (Rp). At 800 °C, compared with primary PBFN, the cathode Rp of (PB)0.95FN is reduced from 0.109 Ω cm2 to 0.063 Ω cm2 in air, whereas the anode Rp is decreased from 0.3808 Ω cm2 to 0.3109 Ω cm2 in H 2. In addition, an electrolyte-supported single cell with (PB)0.95FN symmetrical electrodes achieves a maximum peak power density at 800 °C, which is enhanced by 14.67 % compared with that of PBFN. A-site deficiency on PBFN perovskite shows better electrochemical performance, which is attributed to an increase in oxygen vacancy concentration. The results indicate that (PB)0.95FN is a potential electrode material for SSOFCs. [ABSTRACT FROM AUTHOR]

In order to address the diverse energy storage requirements, there is an urgent need to fabricate supercapacitors with high specific capacitance, long cycle life, high power density and high energy density. Among various transition metal oxide materials, vanadium pentoxide emerges as a promising candidate for cathode materials in supercapacitors. Herein, we report an ion intercalation strategy to synthesize Mn-doped V 2 O 5 (MnVO) and recombine it with reduced graphene oxide (rGO) to form Mn-doped V 2 O 5 @rGO (MnVO@rGO) hybrids with special hierarchical structure. During the hydrothermal process, Mn2+ gradually inserts into the layer spacing of V 2 O 5 to form nanobelts, which could be cross-linked with graphene nanosheets to form MnVO@rGO 3D skeleton network. This unique structure enables the MnVO@rGO electrode to exhibit excellent specific capacitance of 1120 F g−1 at 0.2 A g−1. Outstanding cycling performance is demonstrated by achieving a capacity retention rate of 91.5 % after 2000 cycle. The symmetrical supercapacitor device assembled with MnVO@rGO as both positive and negative electrodes exhibits an energy density of 150.75 and 77.5 W h Kg−1 at power density of 450 and 9000 W kg−1, respectively. Moreover, DFT calculations also have been employed to account for the improved electrochemical performances of MnVO@rGO. Besides, the excellent electrochemical performances of MnVO@rGO indicate that it has broad application prospects in future energy storage devices. [ABSTRACT FROM AUTHOR]

Proton Exchange Membrane Fuel Cells (PEMFCs) represent a promising green solution for energy production, traditionally relying on platinum-group-metal (PGM) electrocatalysts. However, the increasing cost and limited global availability of PGMs have motivated extensive research into alternative catalyst materials. PGM-free oxygen reduction reaction (ORR) catalysts typically consist of first-row transition metal ions (Fe, Co) embedded in a nitrogen-doped carbon framework. Key factors affecting their efficacy include intrinsic activity and catalyst degradation. Thus, alternative materials with improved characteristics and the elucidation of reaction and degradation mechanisms have been the main concerns and most frequently explored research paths. High intrinsic activity and active site density can ensure efficient reaction rates, while durability towards corrosion, carbon oxidation, demetallation, and deactivation affects cell longevity. However, when moving to the actual application in PEMFCs, electrode engineering, which involves designing the catalyst layer, and other critical operational factors affecting fuel cell performance play a critical role. Electrode fabrication parameters such as ink formulation and deposition techniques are thoroughly discussed herein, explicating their impact on the electrode microstructure and formed electrochemical interface and subsequent performance. Adjusting catalyst loading, ionomer content, and porosity are part of the optimization. More specifically, porosity and hydrophobicity determine reactant transport and water removal. High catalyst loadings can enhance performance but result in thicker layers that hinder mass transport and water management. Moreover, the interaction between ionomer and catalyst affects proton conductivity and catalyst utilization. Strategies to improve the three-phase boundary through the proper ionomer amount and distribution influence catalyst utilization and water management. It is critical to find the right balance, which is influenced by the catalyst–ionomer ratio and affinity, the catalyst properties, and the layer fabrication. Overall, understanding how composition and fabrication parameters impact electrode properties and behaviour such as proton conductivity, mass transport, water management, and electrode–electrolyte interfaces is essential to maximize electrochemical performance. This review highlights the necessity for integrated approaches to unlock the full potential of PGM-free materials in PEMFC technology. Clear prospects for integrating PGM-free catalysts will drive cleaner and more cost-effective, sustainable, and commercially viable energy solutions. [ABSTRACT FROM AUTHOR]

Among the challenges related to rechargeable magnesium batteries (RMBs) still not resolved are positive electrode materials with sufficient charge storage and rate capability as well as stability and raw material resources. Out of the materials proposed and studied so far, vanadium oxides stand out for these requirements, but significant further improvements are expected and required. They will be based on new materials and an improved understanding of their mode of operation. This report provides a critical review focused on this material, which is embedded in a brief overview on the general subject. It starts with the main strategic ways to design layered vanadium oxides cathodes for RMBs. Taking these examples in more detail, the typical issues and challenges often missed in broader overviews and reviews are discussed. In particular, issues related to the electrochemistry of intercalation processes in layered vanadium oxides; advantageous strategies for the development of vanadium oxide composite cathodes; their mechanism in aqueous, "wet", and dry non-aqueous aprotic systems; and the possibility of co-intercalation processes involving protons and magnesium ions are considered. The perspectives for future development of vanadium oxide-based cathode materials are finally discussed and summarized. [ABSTRACT FROM AUTHOR]

Layered perovskite related oxides, LnBaCo2O5+δ (Ln = rare‐earth element) are potential ceramic cathodes for intermediate temperature solid oxide fuel cells. Herein, a simple way to tune the performance of NdBaCo2O5+δ (NBC) perovskite as a cathode by doping the Co‐site with bismuth cation is reported. Compared with the parent oxide, the obtained stabilized double perovskites NdBaCo2−xBixO5+δ (x = 0.1 and 0.2) show a much improved electrocatalytic activity, achieving area‐specific resistance of 0.268, 0.107 and 0.152 Ω cm2 at 700 °C in air for NBC, x = 0.1, and 0.2, respectively. Density functional theory results demonstrate that bismuth doping effectively reduces the formation energy of oxygen vacancies. Moreover, the bismuth doping of NdBaCo2−xBixO5+δ cathode is much more robust against CO2 than that of NBC cathode. This work indicates that bismuth doping in the B‐site of LnBaCo2O5+δ may be a highly attractive strategy for the future development of cathode materials. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide (MoO3) possesses high energy density but often suffers from poor electrical conductivity and limited cycling stability when used as a sodium‐ion battery (SIB) anode. To address these issues, the construction of （Molybdenum trioxide‐Molybdenum disulfide）MoO3‐MoS2 heterostructures has proven effective in enhancing electronic conductivity, ion diffusion properties, and structural stability. Guided by the density functional theory (DFT) calculations, which predict favorable Na+ diffusion and adsorption properties, nanorod‐like MoO3‐MoS2 heterostructures are synthesized using a two‐step method. Benefiting from the synergistic effects of the heterostructure and nanosized morphology, the resulting MoO3‐MoS2 electrode exhibits outstanding rate performance (316 mA h g−1 at 10 A g−1) and long‐lasting cycling stability (286 mA h g−1 after 2300 cycles at 5 A g−1) as an SIB anode. In situ XRD measurements reveal that the ultrahigh specific capacity of MoO3‐MoS2 is attributed to the synergistic intercalation‐conversion storage of MoO3 and MoS2. In the pursuit of meeting commercialization requirements, electrodes with adjustable mass loading are also prepared using 3D printing, showcasing the high areal capacity characteristics of the SIBs. This study not only provides theoretical insights into expanding the use of heterojunction materials as SIB anodes but also demonstrates the significant potential for creating high‐energy‐density and cost‐effective SIBs. [ABSTRACT FROM AUTHOR]

The introduction of nanomaterials as modified electrode materials into the field of electrochemical sensing is expected to improve the reliability, sensitivity, selectivity and repeatability of electrochemical sensors in detecting pollutants in the water environment. In this study, copper vanadate nanomaterials (Cu3V2O7(OH)2·2H2O, referred to as CVO) and Cu3V2O7(OH)2·2H2O/polyyaniline (PANI) composite nanomaterials (referred to as CVO/PANI) are successfully prepared and characterized by Fourier transform infrared spectrum (FTIR), X‐ray traveling‐action (XRD), scanning electron microscopy (SEM) and high‐resolution transmission electron microscopy (HR‐TEM). The modified glassy carbon electrodes (GCE) with these two materials are used for the detection of benzoic acid (BA) and exhibit excellent electrochemical sensing performance. The results show that two pairs of semi‐reversible redox peaks exist in both CVO and CVO/PANI modified glassy carbon electrode (GCE) in BA solution. The linear range of CVO and CVO/PANI nanomaterials‐modified GCE is 0.01–2 mm and 0.001–2 mm, and the limits of detection are 2.16 and 0.41 µm, respectively. PANI plays important role in the electrochemical responses of BA at CVO/PANI modified GCE. PANI enhances the intensities of CV peaks and electrochemical determination ability for BA. [ABSTRACT FROM AUTHOR]

In recent years, multicolor electrochromic devices (ECDs) have attracted much attention due to their application potential for rich color similar to RGB mode. Although organic electrochromic (EC) materials are widely used in multicolor electrochromism because of their multicolor properties, remarkable weatherability remains challenging. Inorganic EC materials especially transition metal oxide are particularly attractive for excellent weatherability in ECD fabrication. Moreover, by selection of electrolytes, better ionic transfer efficiency can be rendered in the EC process. Although the morphology regulation of the EC film and the selection of electrolytes in the ion transmission layer play important roles in optimizing EC performance and have been extensively studied, a systematic and comprehensive review is lacking. In this review, the morphology regulation of the EC film and selection rules of electrolytes in the multicolor ECDs is focused, and the advantages and disadvantages of existing ways are discussed. The current application of multicolor ECDs is also outlined and it is hoped that this review can contribute some inspiration to designing and improving multicolor ECDs. [ABSTRACT FROM AUTHOR]

Transition bimetallic sulfides show significant promise for energy‐related applications because of their plentiful active sites and synergistic redox activity. However, limited pore size and low‐conductivity issues hinder their application. The structure of NiCo–S with rich sulfur vacancies is first predicted by density functional theory (DFT) calculations. Different sulfur vacancy concentrations are modeled by DFT calculations, and the results confirm that sulfur vacancies enhance the conductivity of the electrode material and are more beneficial for the adsorption of OH* species. It is verified by the differential charge density that the electric field formed on the surface of the electrode can lead to strong interfacial interactions by electron aggregation, which promotes electron/ion transfer kinetics. Furthermore, NiCo–S nanosheets are prepared on carbon cloth enriched with different concentrations of sulfur vacancies (denoted as NiCo‐Sv‐x, with x representing the concentration of sulfur vacancies) by sulfide etching NiCo‐MOF and annealing under H2/Ar atmosphere. The NiCo‐Sv‐x electrodes obtained are applied to the cathode of supercapacitors and the anode of the oxygen evolution reaction. Through combining experimental and theoretical analysis, the effect of vacancy defect engineering on the electrochemical performance of the electrode materials is further confirmed. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have become promising advanced energy storage and conversion devices because of their high theoretical energy density and specific capacity. Nevertheless, the shuttle effect and slow conversion kinetics of soluble lithium polysulfides (LPSs) have a effect on battery performance. Herein, a Zn–Ni–MOF precursor was synthesized and used to prepare nickel–nitrogen–carbon (Ni–N–C) nanomaterials by removing Zn particles via high-temperature annealing and sacrificial template methods. By incorporating these materials into the Li–S battery separator, the LPS can be effectively blocked and trapped, leading to a conspicuous mitigation of the shuttle effect. Simultaneously, the effective active sites distributed on the surface of Ni–N–C materials facilitate rapid LPSs conversion, resulting in a significant enhancement in electrochemical performance. At a current rate of 0.1C, the initial discharge-specific capacity of 1534 mAh g–1 can be obtained. When the charge–discharge rate is increased to 0.5C, the initial discharge-specific capacity can be measured as 1209 mAh g–1 with a capacity decay rate of only 0.06% per cycle after 300 cycles. Notably, under high-S loading conditions (4.5 mg cm–2), the initial specific capacity is 827.1 mAh g–1 and remains at 634.4 mAh g–1 after 162 cycles at 0.1C. These findings highlight the efficacy of utilizing MOF derivatives to modify conventional Li–S battery separators, effectively mitigating the shuttle effect and enhancing the electrochemical performance of Li–S batteries. [ABSTRACT FROM AUTHOR]

Vanadium‐based oxides are promising candidates for use in aqueous zinc‐ion batteries owing to their open framework structure that facilitates rapid Zn2+ deintercalation. To improve the kinetics, a two‐dimensional nanoribbon‐shaped W‐VO2 cathode material was developed by pre‐embedding tungsten atoms into VO2(B) using a one‐step hydrothermal method. The large interlayer spacing in the W‐VO2 nanosheets aided in the deintercalation of hydrated Zn2+ ions. The 1 % W‐doped electrode exhibited stable cycling, reaching a high capacity of 365.8 mAh g−1 at 0.3 A g−1, with a 92.6 % capacity retention (338.8 mAh g−1) after 200 cycles. Impressively, 84.3 % of the capacity is retained after 1200 cycles at 1 A g−1. The zinc storage mechanism of W‐VO2 was elucidated through in situ X‐ray diffraction and X‐ray photoelectron spectroscopy, highlighting the benefits of tungsten doping on tunnel structure stability and Zn2+ deintercalation reversibility in VO2 electrodes. [ABSTRACT FROM AUTHOR]

Among the cathode materials for advanced lithium-ion batteries, Nickel-rich single crystalline LiNixCoyMn1–x–yO2(NCM) attracts great interest as promising materials owing to their excellent properties, such as superior energy density, high voltage platform, and low cost. However, Nickel-rich single NCM has insufficient cycle stability and cannot meet the demand for the high-rate capacity, which limits its application in EV and HEV. This work applied the strategies of Zr–Y dual doping and Al2O3 coating to improve the electrochemical performance of single crystalline NCM622 cathode. A series of single crystalline LiNi0.6Co0.2Mn0.2O2(NCM622), Zr–Y doped single crystalline NCM622, Al2O3-coated single crystalline NCM622 and Al2O3-coated Zr–Y dual-doped single crystalline NCM622 cathode materials were synthesized through the same roasting process. The Zr–Y double-doped single crystalline NCM622 material shows that Zr–Y ions are successfully doped into the lattice structure, with remarkable 0.1 C, 0.5 C, and 1 C discharge capacities 195.89 mAh·g−1, 181.77 mAh·g−1, and 174.82 mAh·g−1, respectively. The Al2O3 coated Zr–Y dual-doped single crystalline NCM622 materials show that Al2O3 particles are uniformly dispersed and attached to the surface of the coated samples, with cycling performance with retention achieving 98.84% after 50 cycles at 1 C. [ABSTRACT FROM AUTHOR]

In order to solve the problems of poor electrical conductivity and low material utilisation of MnO2 materials in water-based zinc-ion batteries (ZIBs), this paper took agricultural waste coconut shells as raw materials, introduces low-cost, abundant, and green renewable biomass resources into electrode materials, and obtained coconut shell carbon with excellent conductivity through high-temperature carbonization. MnO2 nanopar-ticles were grown on the surface of coconut shell carbon by hydrothermal method to obtain coconut shell carbon@MnO2 composite nanomaterials. By using scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical techniques and other characterization testing methods, the morphology, structure, and electrochemical performance of the composite material were analyzed. The results showed that the specific capacity of coconut shell carbon@MnO2 was still as high as 344.6 mA h/g after 300 cycles at a current density of 100 mA/g, and its performance was much higher than that of commercial MnO2 materials (64.3 mA h/g). The excellent electrical conductivity of coco carbon@MnO2, the nanosized structural design improved the material utilisation, reduced the ionic diffusion path, brought faster ionic diffusion rate and improved the multiplicity performance of the material, which had a good application prospect. [ABSTRACT FROM AUTHOR]

Ag doped LiFePO4, cathode material was prepared by sol-gel method with Ag as the doping element, and CR2032 button cell was assembled based on it. The influence of metal Ag doping molar ratio on the phase structure, microstructure, and corresponding electrochemical performance of LiFePO4 batteries was studied. The results showed that Ag doped LiFePO4 had an olivine like structure with rod-shaped small particles, with a length of approximately 350-500 nm and a width of approximately 100 nm. There was slight agglomeration between the particles. The charge and discharge efficiency of LiFePO4 cathode materials doped with different molar ratios of Ag exceeds 95%. The appropriate doping of Ag molar ratios improved the cycling stability, initial discharge specific capacity, and capacity retention of LiFePO4. As the molar ratio of Ag doping increased, the maximum discharge specific capacity of LiFePO4 first increased and then decreased. The discharge specific capacity of LiFePO4 with a 3% Ag molar ratio reached its maximum value of 123.4 mAh/g. After 30 cycles, the maximum discharge specific capacity was 70.4 mAh/g, and the capacity retention rate was 57.05%. The corresponding charge transfer resistance was 632.7 Ω. It can be seen that the comprehensive performance of 3 % Ag LiFePO4, is the best. [ABSTRACT FROM AUTHOR]

Li-excess cathode materials with a disordered rock-salt structure (DRX) Li1.2Ti0.4Mn0.4O2 and Li1.3Nb0.3Mn0.4O2 were prepared by mechanochemically assisted solid-state synthesis at various synthesis conditions using different lithium sources (Li2O and LiOH). As-prepared samples were characterized by X-ray powder diffraction (XRD), thermal analysis in combination with mass spectrometry (DSC/TG/MS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), electron paramagnetic resonance spectroscopy (EPR), in situ time-resolved synchrotron powder X-ray diffraction (SPXRD) and galvanostatic cycling. The effects of different lithium sources and synthesis temperature on the crystal and local structure and the impact of additional thermal treatment (re-heating) on electrochemical performance of the DRX oxides were investigated. The results obtained show that the optimal synthesis temperature is 950 °C and the use of LiOH as a lithium source leads to the synthesis of the DRX oxides with a fully disordered structure, which is stable when re-heated at a temperature of 600 °C. In addition, re-heating leads to further optimization of the properties of the DRX oxides; this results in a significant improvement of their electrochemical properties. [ABSTRACT FROM AUTHOR]

Cu1-xZnxO samples were synthesized by doping spherical CuO nanomaterials with varying amounts of Zn2+ using the hydrothermal method. The samples exhibited more spherical particles and higher crystallinity when the molar ratio of Zn2+ to Cu2+ was 1:50, but their morphology became agglomerated and inhomogeneous as the doping amount increased. Electrochemical performance tests showed that appropriate Zn doping could improve lithium storage capacity, enhance structural stability, and alleviate volume expansion, thereby improving electrochemical performance. However, excessive Zn doping disrupted sample morphology and decreased electrochemical performance compared to pure CuO samples. Synthesizing Cu1-xZnxO via hydrothermal methods provides a faster synthesis route for cathode materials with good capacity. [ABSTRACT FROM AUTHOR]

In this paper, NaSn0.02Ti1.98(PO4)3/C composite material was prepared by spray drying method combined with high-temperature calcination, which can improve the electrochemical performance of NaTi2(PO4)3. The doping of Sn4+ increases the lattice spacing of NaTi2(PO4)3, thereby accelerating the diffusion coefficient of Na+. The carbon doped on NaTi2(PO4)3 reduces the charge transfer impedance and enhances the ion diffusion coefficient. As a result, NaSn0.02Ti1.98(PO4)3/C exhibits improved electrochemical performance. The specific capacity for the initial discharge of NaSn0.02Ti1.98(PO4)3/C at 1C, 5C, 10C and 20C rates are 108 mAh/g, 86 mAh/g, 76.3 mAh/g, and 71.4 mAh/g, respectively. After 1400 cycles at 10C, the capacity of the material decreases to 64.3 mAh/g, with a capacity retention rate of 84.2%. Therefore, NaSn0.02Ti1.98(PO4)3/C exhibits fast charge/discharge performance as well as cycling stability. [ABSTRACT FROM AUTHOR]

In-situ synthesis of a ternary nanocomposite based on Ag-Fe3O4/rGO by utilizing Azadirachta indica leaf extract as a reducing agent has been carried out. The morphological, EDX, and structural analyses confirm the reduction of GO into rGO by forming crystalline Fe3O4 and Ag nanoparticles in the rGO matrix, with a crystalline size of 25.77 nm. Further, the FTIR, UV-Vis, and BET analyses confirmed the effective interaction between Fe3O4 and Ag nanoparticles in the rGO matrix, tunable bandgap, and a higher specific surface area. Various electrochemical techniques such as cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy have been performed in a 2 M KOH electrolyte to investigate its electrochemical performance. The synthesized ternary nanocomposite exhibits a specific capacitance of 493 Fg−1 at a current density of 1 Ag−1, with notable capacitive retention of 91.5% even after 10,000 cycles. This nontoxic technique provides a substitute pathway for the formation of graphene-based ternary nanocomposites with exceptional structural, morphological, optical, surface, and electrochemical properties. The ternary nanocomposite synthesized through this procedure displays an outstanding specific capacitance, cyclic stability, and corrosion resistance and hence the possibility of using nanocomposite as a promising electrode material can be explored for energy storage devices. [ABSTRACT FROM AUTHOR]

Mixed oxygen ion and electron-conducting materials are viable cathodes for solid oxide fuel cells due to their excellent oxygen transport kinetics and mixed electrical conductivity, which ensure highly efficient operation at low and medium temperatures. However, iron-based double perovskite oxides usually exhibit poor electrocatalytic activity due to low electron and oxygen ion conductivity. In this paper, Ca is doped in PrBaFe2O5+δ A-site to improve the electrochemical performance of PrBaFe2O5+δ. Results show that replacing Pr with Ca does not change the crystal structure, and the Ca doping effectively increases the adsorbed oxygen content and accelerates the migration and diffusion rate of O2- to the electrolyte|cathode interface. The polarization resistance of the symmetric cell PC0.15BF|CGO|PC0.15BF is 0.033 Ω·cm2 at 800 °C, which is about 56% lower than that of PBF, confirming the enhancement of the mixed conduction of oxygen ions and electrons. In addition, the anode-supported single cell has a peak power density of 512 mW·cm-2 at 800 °C. [ABSTRACT FROM AUTHOR]

Chen et al. report a molecular regulation strategy to efficiently control the advantageous OCFGs (a-OCFGs: C O and COO) of ramie activated carbon (RAC), revealing the structure–activity relationship of OCFGs with electrochemical performance in supercapacitors. This regulated RAC with a 3.5–folds–enhanced a-OCFGs achieves a supreme specific capacitance of 286.4F g−1 and excellent capacitance retention rate of 89.7%. Also, twice capacitance of this regulated RAC than that of YP-50F shows its commercial viability. [Display omitted] Effectively managing oxygen-containing functional groups (OCFGs) within activated carbon and methodically elucidating their intricate types and proportions are essential for considerably improving the electrochemical performance of carbon-based supercapacitors. Herein, we designed a ZnCl 2 -based molecular regulation strategy to introduce OCFGs into ramie-activated carbon (RAC), managing different OCFGs and revealing their structure–activity relationship with electrochemical performance. Thus, this regulated RAC, with a 3.5-fold enhancement in advantageous OCFGs (a-OCFGs: C O and COO), exhibits a supreme specific capacitance of 286.4F g−1 at 1 A/g and an excellent capacitance retention rate of 89.7 % at 20 A/g in an aqueous electrolyte, considerably surpassing that of nonregulated RAC (212.0F g−1 and 81.9 %). This confirms that a-OCFGs provide ample ion-storage accommodation and suppress solvent electronic oxidation, thereby enhancing electrochemical performance. Furthermore, its electrochemical performance is competitive with that of the commercial YP-50F (129.2F g−1 at 1 A/g). Therefore, this work not only highlights the contributions of specific OCFGs to high electrochemical performance but also designs a promising commercial electrode material to meet the demands of OCFGs-adequate carbon-based energy storage devices. [ABSTRACT FROM AUTHOR]

The development of efficient and sustainable wastewater treatment technologies is vital to resolve environmental concerns. Finding an effective catalyst for the degradation of organic pollutants in wastewater is challenging. In this study, boron-doped diamond (BDD) particles were synthesized using a high-pressure high-temperature (HPHT) industrial diamond synthesis technology. BDD was investigated as an efficient electrode catalyst to convert organic pollutants into biodegradable substances. BDD self-supporting electrodes exhibited excellent properties with a relative density of 93.07%, an electrical resistivity of 2.71 × 10−4 Ω·m. Furthermore, BDD particles showed superior electrochemical characteristics such as a rapid electron transfer coefficient of about 0.5, good reversibility and redox properties. The BDD self-supporting electrode achieved a methylene blue degradation rate of 98.72% within 60 min. Our research provides valuable insights into using BDD as an effective electrochemical catalyst for wastewater treatment, which can help promote the development of environmentally friendly and economically viable technologies. [ABSTRACT FROM AUTHOR]

Symmetric solid oxide cells (SSOCs) have attracted much attention due to their high energy conversion efficiency and simple manufacturing. The present study involves the synthesis of a class of double perovskite oxides, which serve as electrodes for SSOCs. These oxides exhibit exceptional stability in an oxidizing atmosphere, maintaining their single-phase double perovskite structure. Moreover, they facilitate the co-exsolution of metal nanoparticles from both A and B-sites under reducing conditions. By optimizing the doping amount of Bi in Sr 2- x Bi x FeTiO 6− δ (SB x FT), co-exsolved Bi and Fe nanoparticles decorated double perovskite oxides were obtained in reducing atmosphere and employed as high-performance electrodes for SSOCs. With Sr 1.2 Bi 0.8 FeTiO 6-δ as the electrode, the maximum power density achieves 537 mW cm−2 at 850 °C. In electrolysis mode, the current density for pure CO 2 electrolysis reaches 1.43 A cm−2 at an applied voltage of 1.5 V and 850 °C. All of these results indicate that co-exsolution of components on perovskite is an effective design technique for creating materials with desirable features. [Display omitted] • The novel co-exsolved metal nanoparticles decorated double perovskite oxides were obtained by Bi doping. • The Sr 2- x Bi x FeTiO 6 - δ were as the electrodes for symmetric solid oxide cells. • In SOFC mode, SB 0.8 FT exhibits excellent electrochemical performance. • In SOEC mode, SB 0.8 FT shows excellent CO 2 reduction properties and stability. [ABSTRACT FROM AUTHOR]

Cholesterol is a major cause for cardiovascular diseases; and therefore, timely detection of cholesterol is of paramount importance to prevent such diseases. Herein, a non-enzymatic sensor for the detection of cholesterol has been fabricated using polyaniline (PANI) and its nanocomposites (NCs) with ZnO nanoparticles (NPs). For this purpose, a series of NCs has been synthesized by varying the loading of the ZnO NPs as 2%, 3%, 5% and 8% with respect to the weight percentage of the aniline monomer. In addition, two different doping agents, namely camphor sulfonic acid (CSA) and hydrochloric acid, have been used to prepare PANI and its NCs. Electrochemical studies have revealed that as the amount of ZnO NPs increased, the capacitive behavior of the composite also increased. Similar trend was observed in case of HCl-doped polyaniline NCs. PANI/ZnO 8% NCs for both HCl and CSA dopant indicated good capacitive behavior for sensing cholesterol. The best electrode was further tested for sensitivity, and was found to exhibit a value of 0.38 mA mM−1 cm−2. The limit of detection of the prepared sensor was found to be 0.30 mM concentration in PBS buffer under the linearity range of 0.75 mM to 1.5 mM (adj. R2 = 0.97). Polyaniline/ZnO nanocomposites (2%, 3%, 5%, and 8%) with two different doping agents (CSA and HCl) were synthesized and compared. Physical, optical, and electrochemical properties of the nanocomposites resulted in favor of 8% ZnO loadings. Cholesterol sensor fabricated with PANI-HCl/ZnO 8% nanocomposite showed better response than PANI-CSA/ZnO 8%. LOD of the prepared non-enzymatic cholesterol biosensor was found to be 0.30 mM. The fabricated cholesterol sensor using PANI/ZnO nanocomposite exhibited a sensitivity of 0.38 mA mM−1 cm−2. [ABSTRACT FROM AUTHOR]

TiNb 2 O 7 powders were prepared via the hydrothermal method followed by the post-calcination reaction. The as-synthesized TiNb 2 O 7 powders were further coated with different amounts of anatase TiO 2 , ranging from 4 mol% to 20 mol%. The deposited TiO 2 particles could be easily observed on the surface of TiNb 2 O 7 through HR-TEM. When the amounts of TiO 2 on TiNb 2 O 7 surface were increased from 0 mol% to 12 mol%, the capacity retention of TiNb 2 O 7 batteries at 0.2C for 100 cycles was increased from 29.50 % to 63.06 %. Furthermore, the volume of generated gas from the batteries during cycling tests was decreased from 0.0035 mL to 0.0015 mL. The coating of anatase TiO 2 avoided direct contact between TiNb 2 O 7 and electrolyte to suppress the interface reaction and resolve the gassing problem of TiNb 2 O 7. Therefore, the long-term cyclability of TiNb 2 O 7 -based batteries was improved via TiO 2 coating on TiNb 2 O 7. However, the excessive amounts of TiO 2 coating on TiNb 2 O 7 surface induced a significant increase in the charge transfer resistance of prepared batteries and the suppression of oxidation/reduction reactions of Nb5+/Nb4+ and Nb4+/Nb3+ in TiNb 2 O 7 , resulting in an unsatisfactory discharge capacity of TiNb 2 O 7. The appropriate amounts of TiO 2 coating could effectively improve the long-term cyclability of TiNb 2 O 7 and preserve the discharge capacity of TiNb 2 O 7. [ABSTRACT FROM AUTHOR]

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To explore high-performance carbon anodes for potassium-ion batteries, monodisperse novel hollow carbon spheres (MHCSs) were synthesized via a combination of hydrothermal reactions and high-temperature pyrolysis using 2,4-dihydroxybenzoic acid and hexamethylenetetramine as the main raw materials. The synthesized MHCSs range from 140 to 260 nm in size with a large specific area of 466 m2 g-1. The potassium storage performance and dynamics of MHCSs in KN(SO2F)2 (KFSI) and KPF6 electrolytes were systematically investigated. In the KFSI electrolyte, the MHCSs have a higher reversible capacity, better cycling stability, better rate performance, and faster electrode process dynamics than in the KPF6 electrolyte. The excellent electrochemical performance of MHCSs in the KFSI electrolyte is attributed to the hollow structure of the material and the formation of a KF-rich and uniform solid-electrolyte interface film. [ABSTRACT FROM AUTHOR]

This study reclassifies Fe–P network types in the LiFePO 4 structure and comprehensively analyzes their associated electrochemical properties. Six low-energy Fe–P networks were examined for variations in energy, voltage, volume, and charge across Li compositions from 0 to 1. We calculated the relative formation energy for each network and identified stable components to determine the voltage platform. Most structures align with the ground state, FePO 4 /LiFePO 4 two-phase configuration. Notably, certain Fe–P networks (FY, AC ′ , and a subset of AA ′ ) exhibit stability in Li x FePO 4 ( 0 < x < 1 ), causing a distinct voltage platform jump during charge and discharge. Volume change analysis reveals comparable trends among similar Fe–P network structures. Charge changes in FePO 4 /LiFePO 4 are primarily element-dependent rather than Fe–P network-dependent. Our findings suggest the potential design of new structures with improved electrochemical performance for specific Fe–P network types. [ABSTRACT FROM AUTHOR]

Lithium metal solid‐state battery is the first choice of batteries for electromobiles and consumer electronic products because of the specific capacity of 3860 mAh g−1 and high electrochemical potential (−3.04 V) of Li metal. Flexible polymer solid electrolytes have become the optimal solution to produce high energy density lithium batteries with arbitrary size and shape. In this work, we introduce a halide perovskite, CsSnI3, into the polyethylene oxide/lithium bis‐(trifluoromethanesuphone)imide (PEO–LiTFSI) polymer matrix. The CsSnI3 could form a LixSn alloy with Li, leading to homogenization of the electric field and Li+‐flux at the interface, Sn atom also bonds with the TFSI− anion to provide more dissociated Li+. Besides that, the I atom could interact with Li to form an electronic insulation with a strong blocking effect on electron tunneling. As a proof of concept, the synergy mechanism of the PEO–LiTFSI–CsSnI3 electrolyte improves the stable cycle life of the symmetric battery to more than 500 h, and the Li+ conductivity raised to 6.1 × 10−4 S cm−1 at 60°C. The application of the "zwitter ions analog" halide perovskite in PEO–LiTFSI provides a new choice among various methods to improve the electrochemical performance of polymer solid‐state batteries. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO2) nanoparticles were modified by graphitic carbon nitride (GCN) and polylpyrrole (Ppy) to enhance their electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the Ppy/GCN/MnO2 material were characterized and compared with those of pristine MnO2. It is found that surface modification can improve the structural stability of MnO2 without decreasing its available specific capacitance. The electrochemical properties of synthesized Ppy/GCN/MnO2 electrode were evaluated using cyclic voltammetry (CV) and AC impedance techniques in 5 M KOH electrolyte. Specific capacitances of 486, 815, 921, and 1377 F/g were obtained for MnO2, Ppy/MnO2, GCN/MnO2, and Ppy/GCN/MnO2, respectively, at 5 A/g. This improvement is attributed to the synergistic effect of GCN and Ppy in the Ppy/GCN/MnO2 electrode material. The Ppy/GCN/MnO2 electrode in KOH has average specific energy and specific power densities of 172 Wh kg−1 and 2065 W kg−1, respectively. Only 2 % of the capacitance's initial value is lost after 10,000 cycles. The resulting Ppy/GCN/MnO2 nanocomposite had very stable and porous layered structures. This work demonstrates that Ppy/GCN/MnO2 nanomaterials exhibit good structural stability and electrochemical performance and are good materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In this study, SiO@graphite@C@Al2O3 (SiO@G@C@A) composites are synthesized by varying the content of Al2O3, and their morphology and structure and their electrochemical performance are investigated in detail. The results indicate that the SiO/G@C@A-2 composite exhibits a specific capacity of 977.1 mA h g−1 at a current density of 0.1 A g−1 with a coulombic efficiency of 71.15%. Even after 100 cycles at a current density of 0.5 A g−1, it retains a delithiated specific capacity of 640.7 mA h g−1 and a capacity retention rate of 73.56%. Moreover, when the current density is raised to 2 A g−1, it maintains a delithiated capacity of 568.4 mA h g−1 and a capacity retention rate of 58.51%. The excellent electrochemical performance is ascribed to the synergistic effect of different components. The inclusion of graphite enhances overall conductivity while mitigating the volume expansion of the SiO. The application of asphalt pyrolytic carbon as a coating effectively isolates the SiO from the electrolyte, further reducing volume expansion and enhancing conductivity. The introduction of Al2O3 can absorb trace amounts of hydrogen fluoride (HF) generated during charge and discharge processes. Additionally, it facilitates the formation of an AlF3 film on the particle surfaces, which hinders and decelerates electrolyte dissolution into the electrode. The prepared composites exhibit promising prospects as lithium-ion battery anode materials. [ABSTRACT FROM AUTHOR]

Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical performance. However, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH4 + storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [(NH4)2V10O25.8H2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g-1, 252 mAh g-1 at 0.5 A g-1 with ~80% capacitance retention after 10,000 cycles), which benefits from extra active sites, unimpeded NH4 +-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the chargestorage capability and induce structural disintegration. The superior NH4 +-storage behavior is achieved with the reversible intercalation/deintercalation process of NH4 + accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor (FQSS HSC) also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems. [ABSTRACT FROM AUTHOR]