Cycling Performance Research Articles

Antifreezing functionalized-alginate-based electrolytes for zinc-ion batteries

Flexible zinc-ion batteries (ZIBs) assembled with hydrogel electrolyte are considered as promising flexible energy storage devices because of their inherent safety and versatility. However, the ionic conductivity and mechanical properties of most hydrogel electrolytes are not satisfactory, Furthermore, they will freeze at subzero temperature due to existing water. In this work, a freezing resistant polycarboxylic double network gel electrolyte (SIP-CS) with high ionic conductivity (14.36 mS cm⁻1 at −20 °C) and excellent mechanical property (fracture stress of 241.5 kPa and fracture strain of 1011 %) is prepared. Iminodiacetic acid (IDA) is applied to modify the alginate mainchains with many -COOH groups, which could provide channels for ion migration and endow hydrogel with high ionic conductivity. Additionally, sorbitol, containing lots of hydroxyl groups, is applied as a cryoprotectant to enhance the subzero performance of the electrolyte, because sorbitol could break the hydrogen bonds between water molecules, inhibit the formation of ice crystals, and reduce the freezing point of the gel electrolyte. The freezing point of SIP-CS is −37.0 °C, enabling the electrolyte to perform well at low temperatures. The flexible quasi solid Zn-MnO2 battery is assembled to evaluate the low-temperature electrochemical performance of SIP-CS. The assembled Zn-MnO2 battery shows good cycling and stable electrochemical performance, which proves the excellent antifreezing property of SIP-CS. This work provides a new strategy for preparing an electrolyte with good withstand low-temperature capability.

Molecular Control Based on Electrostatically Driven Modification for Solid-State Lithium Metal Batteries.

With the rapid development of energy vehicles, the demand for high-safety and high-energy-density battery systems, such as solid-state lithium metal batteries, is becoming increasingly urgent. Polyethylene oxide (PEO), as a commonly used electrolyte in solid-state batteries, has the advantages of easy processing and good interface compatibility but also faces the issue of poor ionic conductivity. In this study, we have enhanced the mechanical properties and ion conductivity of PEO electrolytes significantly, stabilizing electrochemical cycling, utilizing positively charged MXene as a modifying material for PEO solid electrolytes and leveraging stronger electrostatic forces. With these enhanced properties, the modified solid electrolyte in Li/Li cells demonstrates excellent cycling stability of over 430 h at 0.1 mA cm-2. Furthermore, the Li/LiFePO4 cells show excellent cycling performance, and the capacity retention rate is 92.1%.

3D Ternary Hybrid of VSe2/e‐MXene/CNT with a Promising Energy Storage Performance for High Performance Asymmetric Supercapacitor

AbstractMXene and TMDs are two of the emerging electrode materials for supercapacitors owing to their unique physicochemical properties such as high conductivity, large surface area, and rich redox active sites. However, sheet restacking, volume expansion and oxidation hinder these materials from being used in practical applications. In this work, a 3D ternary hybrid structure of metallic VSe2, Ti3C2Tx MXene and carbon nanotube was designed to address some of the challenges in 2D materials‐based electrodes for supercapacitor application. The exfoliated MXene and CNT decorated VSe2 3D structure showed excellent synergy between each component to deliver promising energy storage and cycling performance. The ternary hybrid structure also can suppress the surface oxidation of MXene sheets during the hydrothermal reaction. Furthermore, an asymmetric supercapacitor fabricated with VSe2/e‐MXene/CNT and MoS2/MXene delivered the highest energy density of 35.91 Wh/kg at a power density of 1280 W/kg and a remarkable cycle life.

Controlled Interfacial Tailoring of Hierarchical Silicon Synergizes Charge Transport Enabling Stable and Fast Lithium Storage.

Silicon is a promising anode material candidate but encounters volume change and capacity decay issues. Although diverse demonstrations in structural and interfacial engineering, the performance toward industrial applications remains to be improved. Herein, a controlled interfacial tailoring strategy is proposed for micro-nano hierarchically structured silicon. The resultant granules, consisting of randomly interconnected silicon debris modified by an electrically conductive carbon layer and a superionic sulfide conductor specifically in a controlled form (nanoparticles, coats, and matrices), attain distinctly different cyclic performances. As the carbon coating generally provides electron transfer paths for silicon, the introduced fast ion conductor exhibits a strong correlation with its configuration in facilitating ion transportation as well as improving the materials utilization and cyclic stability. Impressively, the granules encapsulated with a fast ion conductor layer show remarkably improved cycling performance and rate capability, attributable to a decent synergy of transmitting both electrons and lithium ions throughout the granule.

Constructing a Functional Fast‐Ion Conductor Interface for Vertically Aligned Titanium Boride Nanosheets to Achieve Superior Sodium‐Ion Storage Performances

AbstractDesigning excellent anode materials to enhance the sluggish interfacial kinetics of Na+ is a key challenge in improving the electrochemical performance of sodium‐ion batteries (SIBs). Herein, an ultra‐thin fast‐ionic conductor NaB5C coating TiB2 nanoflowers with vertically aligned nanosheet arrays to form yolk–shell TiB2@NaB5C (TBNBC) nanospheres as an anode material for SIBs. The unique structure creates direct and short ion/electron transfer pathways and reserves enough space to prevent the uneven electrochemical reactions from TiB2 nanosheets aggregation and stacking, thus ensuring the long‐term cycling stability of SIBs. Additionally, the NaB5C coating with fast‐ionic conductor functional interphase provides rapid Na+ transport channels and effectively reduces the Na+ de‐solvation barrier, accelerating Na+ reaction kinetics. Furthermore, a homogeneous and robust solid electrolyte interphase (SEI) film including inorganic boron species and fluorine‐rich inner layer is constructed on the TBNBC electrode to delocalize stress and induce a uniform Na+ flux, further promoting fast Na+ interphase reaction kinetics. Consequently, the optimized composites achieve ultrastable cycling performances of 173 mAh g−1 over 5000 cycles at 10 A g−1. More importantly, they also exhibit an outstanding capacity of 182.2 mAh g−1 at −20 °C. This work offers opportunities for the energy storage use of transition metal borides under extreme conditions.

Replenish the Electron-Deficient State of Carbonyl Carbon Atoms to Achieve Stable Li-S Battery.

Carbonate-based electrolytes are widely used in Li-ion batteries (LIBs) due to their safe, stable properties and wide operating temperature range. However, the nucleophilic attack at carbonyl carbon atoms by polysulfide anions and the low solubility of lithium nitrate (LiNO3<0.1m) in carbonate-based electrolytes seriously hinder the application of lithium-sulfur (Li-S) batteries in carbonate-based electrolytes. Herein, the electrophilicity of carbonyl carbon atoms is gradually reduced through solvent molecules redesign, eliminated the attack of polysulfide anions on carbonyl carbon atoms, and also changed the intermolecular interactions in the electrolyte, improving the solubility of LiNO3 (>1.0m) and forming stable LiNxOy-containing SEI on the surface of the lithium metal. The assembled Li-S battery with these designed solvent molecules delivers an initial discharge capacity of 1251.7mAhg-1 at 0.1C. In addition, the lithium-sulfur battery assembled with the designed solvent molecule has a discharge capacity of 631mAhg-1 after 420 cycles at 0.2 C, with a capacity retention of ≈60%. Moreover, the Li||Li symmetrical cell shows stable cycle performance over 1200h at 0.5mAcm-2 and 0.5mAhcm-2.

Selective Self‐Assembly of Atomically Dispersed Iron and Cobalt Dual Atom Catalyst on Anisotropic Mesoporous Carbon Particles for High Performance Seawater Batteries

AbstractNa‐seawater batteries (SWBs) are environmentally friendly energy storage system that utilizes abundant seawater as an electrolyte alternative to conventional distilled water‐based and organic electrolytes. To achieve high energy efficiency in Na‐SWBs, it is necessary to enhance the activity of bifunctional oxygen electrocatalysts. In this study, an atomically dispersed iron and cobalt dual‐atom nitrogen‐doped lens‐shaped mesoporous carbon (FeCo‐LMC) particles is synthesized as a SWB cathode material using the spinodal decomposition of the polymer blend and selective precursor positioning. The well‐aligned mesoporous structure and synergetic effect of the dual‐atom site realize FeCo‐LMC as a comparable bifunctional oxygen catalyst with the lowest overpotential difference (EOER−EORR) among the other catalysts with natural seawater electrolyte. When applied to the SWB system, the FeCo‐LMC shows a highly improved charge/discharge performance compared to Pt/C and a stable cycling performance for 200 h. Density functional theory calculations reveal the enhanced oxygen catalytic activity of FeCo‐LMC owing to electron delocalization and d‐band center adjustment of FeN4–CoN4 structure.

Poly (Propylene Carbonate) with Extremely Alternating Structure Used as Binders for High-Loading Cathodes by Solvent-Free Method in High-Performance NCM811 Batteries

The cathode affects the capacity, working voltage, and cost of lithium-ion batteries. Although the binder is a small part of the cathode material, it is particularly important to the performance of the batteries. Therefore, the design and development of polymer binders with different structures and characteristics is an important topic. In this paper, an NCM811 cathode (PPC-NCM) was prepared by a solvent-free method using poly (propylene carbonate) (PPC) as the binder, with an active substance loading of 10 mg/cm2. To explore the effect of the PPC binder on the electrochemical performance of the NCM811 cathode, the discharge capacity was 112.2 mAh/g with a 76.1% capacity retention after cycling more than 200 cycles at 1 C, which has a significantly better cycling performance than that of a PVDF-NCM/Li battery. The PPC/NCM/graphite full cells were also assembled to demonstrate the practical application potential of this work. It was shown that PPC as a binder can improve the cycling stability of NCM811/Li and NCM811/graphite full cells. The PPC binder used in the NCM811 cathode not only makes it extremely easy to prepare dry electrodes, but also makes it very simple to recover the electrode material by heating in the case of battery failure. This paper provides a new idea for the industrialization and development of a novel binder.

Study of Pr doped nanocrystalline LiCoO2 cathode material for spintronic and energy storage applications: A theoretical and experimental analysis

In this study, Pr3+ substituted LiCoO2 lithium-rich cathode materials were prepared using the sol-gel auto-combustion technique to enhance cycling performance. LiCo1-xPrxO2 samples having Pr concentrations x = 0.00–0.10 were synthesized. X-ray diffraction (XRD) showed a rhombohedral structure with space group R-3m, further verified by the Rietveld refinement. Field emission scanning electron microscopy (FESEM) revealed the presence of distinct and well-defined submicron-scale grains. FTIR spectroscopy confirmed Co–O stretching bonds within 590–560 cm−1 and revealed peaks at around 560–590, 830–860, and 1320-1480 cm−1, which could be attributed to the electrochemical performance of Pr-doped species. Moreover, EDX spectroscopy confirmed the typical elemental peaks of only Co, Pr, and O, confirming the required phase presence. The cyclic voltammetry showed improved reversibility and stability due to Pr doping. The first-principles computations were performed using the lattice constant extracted from XRD measurements. The pure LiCoO2 with a semiconducting nature became half-metallic due to Pr doping (LiCo0.84Pr0.16O2). The magnetic properties indicate that LiCoO2 and LiCo0.84Pr0.16O2 exhibit positive magnetic order, which shows that these are suitable candidates for spintronic applications. The pure LiCoO2 revealed intercalation voltages of 4.10–2.73V and a theoretical capacity 40–203 mAh/g. Meanwhile, for LiCo0.84Pr0.16O2, the intercalation voltages and theoretical capacity improved to 4.42–2.85 V and 42 to 211 mAh/g, respectively. The combined experimental and theoretical study suggests that Pr-doped LiCoO2 is suitable for spintronic applications and energy applications such as composite cathodes.

Review and prospect on Metal-organic framework-based Separators for Lithium–Sulfur Battery

With the continuous advancement of technology, wearable smart devices and electric vehicles (EVs) have become an integral part of our daily lives. The increasing demand for energy from these devices and vehicles has driven the pursuit of high-performance rechargeable battery technology. In particular, the widespread adoption of electric vehicles has set higher standards for the energy density and cycle life of batteries. However, the energy density of the widely used lithium-ion batteries is currently limited by the theoretical capacity of commercial cathode materials, and there are certain challenges in terms of safety and cost-effectiveness. Therefore, the development of a new generation of rechargeable batteries with higher energy density, better safety, and more economical cost is particularly urgent. Lithium-sulfur batteries, due to their high energy density, high economic benefits, and high environmental friendliness, are considered to be one of the most promising successors to the widely used lithium-ion batteries. However, in practical applications, the electrochemical performance of lithium-sulfur batteries still needs to be improved. In particular, the poor conductivity of sulfur/lithium and the shuttle effect of polysulfides make the cycle life of the battery less than ideal, and lithium-sulfur batteries (LSB) are still far from achieving large-scale commercialization. The separator used in lithium-sulfur batteries plays a crucial role in its cycle performance and safety. The current commercial separator lacks the ability to effectively regulate the shuttle of polysulfides and is prone to thermal runaway at high temperatures. Therefore, to improve these issues, various functional materials have been used to modify the separator. Among them, as a new type of porous coordination polymer, metal organic frameworks (MOFs) have become a promising material for modifying separators due to their large specific surface area and highly ordered tunable nano-holes.At the same time, their rich inorganic nodes and designable organic ligands allow for the customization of pore chemistry at the molecular level, which can interact with the electroactive components in lithium-sulfur batteries in a tunable manner. This article reviews the reaction mechanism of lithium-sulfur batteries and the structural advantages of MOFs in terms of pore chemistry and morphology and briefly introduces the research progress of MOF-based interfacial layers for the functionalization of LSB separators in recent years. It elaborates on the mechanisms by which various modified separators improve electrochemical performance and provides a prospect for the development prospects of the field.

High-Performance Solid-State Lithium Metal Batteries of Garnet/Polymer Composite Thin-Film Electrolyte with Domain-Limited Ion Transport Pathways.

The integrated approach of interfacial engineering and composite electrolytes is crucial for the market application of Li metal batteries (LMBs). A 22 μm thin-film type polymer/Li6.4La3Zr1.4Ta0.6O12 (LLZTO) composite solid-state electrolyte (LPCE) was designed that combines fast ion conduction and stable interfacial evolution, enhancing lithium metal interface stability and cycling performance. The ether-based molecular coordination groups/clusters formed by triethylene glycol dimethyl ether (TGDE) and anions facilitated the movement of Li+ between the polymer chain segments. These specific coordination clusters significantly "constrained" the interaction between anions and Li+, inducing the anions to follow the clusters to the Li metal and preferentially participate in solid electrolyte interface (SEI) derivatization. The inorganic salt-rich gradient SEI modulates Li+ deposition and inhibits uncontrolled dendrite growth, achieving stable cycling of Li symmetric cell at 0.2 mA cm-2 for over 2000 h. Furthermore, the Li||NCM811 cell at a rate of 0.1 C exhibits an initial discharge capacity of 194.5 mAh g-1, maintaining a capacity retention rate of over 90% after 500 cycles. This work demonstrates the importance of domain-limited ion clusters in ion transport and interfacial evolution, providing a perspective for solid-state LMBs.

Internal Electron-Donation Allocation Design for Intrinsic Solubilization of Lithium Nitrate in Ester Electrolyte for Stable Lithium Metal Batteries.

Lithium metal batteries (LMBs) have become a hot topic in the research of next-generation advanced battery technology due to their high specific energy. However, the high reaction activity between lithium metal and electrolyte is considered one of the key bottlenecks limiting large-scale applications of LMBs. As a classic electrolyte additive, LiNO3 significantly improves the stability of lithium metal in ether-based electrolytes. However, its solubility in carbonate-based electrolytes widely used in lithium-ion batteries is extremely low, and its protective effect on lithium metal is limited, which has become a key obstacle to the commercial application of lithium metal batteries. Here, we enhanced the local negative charge density of carbonyl oxygen atoms in carbonate molecules by introducing electron donors, making it easier for them to coordinate with Li+, thereby weakening the interaction between Li+ and NO3-, and significantly increasing the solubility of LiNO3 in ester electrolytes. The modified ester solvent promotes the derivatization and decomposition of salt anions, leading to the formation of a dense SEI layer rich in LiF and LiNxOy. This significantly improves the stability of lithium metal in ester-based electrolytes. The assembled Li||Li symmetric battery shows excellent cycling performance of over 4000 hours.

Sn Penetrated Zincophilic Interface Design in Porous Zn Substrate for High Performance Zn-Ion Battery.

Rechargeable zinc-ion batteries are considered an ideal energy storage system due to their low cost and nonflammable aqueous electrolyte. However, dendrite growth, hydrogen evolution reaction, and self-corrosion of zinc anode brought about serious safety risks including short circuits and electrode expansion. Therefore, a modified host-design strategy with a 3D porous structure and bulk-phase penetrated zincophilic interface is proposed to boost the stability and lifetime of the Zn anode. The porous Zn substrate is constructed by universal HCl etching and the uniform and tight Sn-penetrated zincophilic interface is formed by effective electron beam evaporation (EBE). The porous substrate can uniform zinc ion flux and the Sn coating could effectively improve zinc ion deposition behavior, thus inhibiting the risk of dendrites growth and side reaction. As a result, the 3D Zn substrate with Sn interface (3D Zn@Sn) exhibits prolonged galvanostatic cycling performance up to 4500h with a low polarization of ≈25mV (1mAcm-2, 1mAhcm-2) in the symmetric cell. The full cell assembled with KVOH@Ti could maintain a high specific capacity of 148.6mAhg-1 after 500 galvanostatic cycles (10Ag-1). This work proposed an improved electrode design to realize the high performance of zinc ion batteries.

Functionalization Strategies of Iron Sulfides for High-Performance Supercapacitors

AbstractSupercapacitors have emerged as a promising class of energy storage technologies, renowned for their impressive specific capacities and reliable cycling performance. These attributes are increasingly significant amid the growing environmental challenges stemming from rapid global economic growth and increased fossil fuel consumption. The electrochemical performance of supercapacitors largely depends on the properties of the electrode materials used. Among these, iron-based sulfide (IBS) materials have attracted significant attention for use as anode materials owing to their high specific capacity, eco-friendliness, and cost-effectiveness. Despite these advantages, IBS electrode materials often face challenges such as poor electrical conductivity, compromised chemical stability, and large volume changes during charge–discharge cycles. This review article comprehensively examines recent research efforts aiming at improving the performance of IBS materials, focusing on three main approaches: nanostructure design (including 0D nanoparticles, 1D nanowires, 2D nanosheets, and 3D structures), composite development (including carbonaceous materials, metal compounds, and polymers), and material defect engineering (through doping and vacancy introduction). The article sheds light on novel concepts and methodologies designed to address the inherent limitations of IBS electrode materials in supercapacitors. These conceptual frameworks and strategic interventions are expected to be applied to other nanomaterials, driving advancements in electrochemical energy conversion.

Carbon-Encapsulated Bimetallic Fe-W-Based Selenides with Abundant Heterogeneous Conductive Network for Superior Potassium Ion Storage.

Potassium-ion batteries (KIBs) are one of the most promising alternatives to lithium-ion batteries (LIBs) due to their high ion mobility, abundant resources, and low cost. However, the problems of low capacity and poor cycling stability of KIBs remain unsolved; therefore, it is crucial to explore alternative electrode materials suitable for reversible insertion and extraction of K+. Herein, carbon-encapsulated Fe3Se4/WSe2 microsphere material assembled from nanosheets with abundant heterogeneous interfaces and expanded interlayer spacing (denoted as FWSC) is designed as an anode material for superior potassium ion storage. The microspheres assembled from nanosheets, the outer carbon coating, and the expanded layer spacing can expose more active sites and improve the electronic conductivity and structural stability of the material. The abundant heterogeneous conductive network not only improves the conductivity of the material but also enhances the reversibility of the electrochemical reaction. As a result, the FWSC exhibits outstanding cycling stability, excellent rate performance (the capacity retention is 53% when the current density is from 0.5 to 1.0 A g-1), and stable long-term cycle performance (a capacity of 209 mAh g-1 at 1.0 A g-1 over 1000 cycles).

Boosting de-solvation via halloysite nanotubes-cellulose composite separator for dendrite-free zinc anodes

Aqueous zinc-ion batteries (ZIBs) have attracted considerable attention owing to intrinsic advantages, which encompass inherent safety and a cost-effective manufacturing process. Nevertheless, the lifespan of Zn anodes is limited by inclement dendrite growth and adverse side reactions, impeding the commercial viability of ZIBs. In this study, we engineered a multifunctional cellulose-based separator (HC) synthesized from halloysite nanotubes (HNTs) and cellulose to address these challenges effectively. Leveraging the exceptional water adsorption capacity and the unique inner positive and outer negative tubular structure of HNTs molecules, the HC separator facilitates the de-solvation behavior of [Zn(H2O)6]2+ and promotes uniform deposition of Zn2+. Furthermore, the HC separator demonstrates superior wettability, excellent flexibility, and higher ionic conductivity, which further lead to dendrite-free zinc deposition, a 2700-h cycling lifespan, and a coulombic efficiency (CE) of 98.88 % after 100 cycles. Notably, the ZIBs incorporating the HC separator exhibit exceptional cycling performance, retaining 83.5 % of their capacity after 2000 cycles at 5 A g−1. This novel approach offers a valuable direction for the advancement of cost-effective and durable ZIBs.

Synthesis of Trisiloxane with the Dioxaborolane Group as a Cathode Film-Forming Electrolyte Additive for High-Temperature LiMn2O4/Li4Ti5O12 Batteries.

LiMn2O4 batteries have been widely applied as various portable electronic devices and electric vehicles owing to the merits of low cost, high operating voltage, excellent rate capability, and environmental friendliness. However, the poor performance at elevated temperatures remains a serious technical challenge in terms of commercial application purposes. A borate-containing trisiloxane compound of TSMBO is designed and synthesized as a cathode film-forming electrolyte additive to improve the electrochemical performances of LiMn2O4/Li4Ti5O12 batteries, especially at high temperatures of 55 °C. Atomic force microscopy measurement confirms that the trisiloxane moiety in TSMBO can construct a cathode electrolyte interface (CEI) with higher mechanical strength and better flatness compared to the disiloxane moiety in the TSMBO analogue with a similar chemical structure. The robust CEI film on the surface of the LiMn2O4 cathode and the inhibited hydrolysis of LiPF6 in the electrolyte significantly suppress the dissolution of Mn from the LiMn2O4 cathode and maintain the structural integrity of the LiMn2O4 lattice over cycling. Thus, the LiMn2O4/Li4Ti5O12 coin cell using the TSMBO-containing electrolyte with an optimized addition level of 0.5 wt % exhibits a higher capacity retention of 49.3% compared with 34.3% for the baseline electrolyte after 300 cycles under 1C rate at 55 °C. The LiMn2O4/Li4Ti5O12 pouch cell tests show excellent high-temperature and cycling performance at 55 °C and a higher capacity retention of 90.4% after 500 cycles at 2C compared to 79.7% for that with the baseline electrolyte after 430 cycles at 2C. This work demonstrates that TSMBO is a promising electrolyte additive for practical use to improve the cycling stability of LiMn2O4/Li4Ti5O12 batteries at elevated temperatures.

Entropy‐Modulated Short‐Chain Cathode for Low‐Temperature All‐Solid‐State Li−S Batteries

AbstractAll‐solid‐state Li−S batteries (ASSLSBs) due to high theoretical energy density and exceptional safety are highly desirable for electric aircraft. However, as the flight altitude rises, the low‐temperature performance is hampered by inadequate practical capacity. Here, we discover that low‐temperature sulfur utilization is constrained by the multi‐step endothermic conversion reaction. By introducing multi‐chalcogen to modulate the local entropy, a short‐chain molecule cathode is designed to shorten the reduction pathways and enhance low‐temperature discharge capacity. Furthermore, the mismatched lithiation lattice of the short‐chain cathode reduces the decomposition energy barriers, thus enhancing low‐temperature charge/discharge reversibility. The designed short‐chain cathode exhibits high cathode utilization (99.4 %) and cycling stability (400 cycles, 92.2 % retention) at room temperature, as well as delivers excellent discharge capacity (579.6 mAh g−1, −40 °C) and cycling performance (100 cycles, 98.4 % retention, 394.9 Wh kg−1electrode, −20 °C) at low temperature. This study presents new opportunities to stimulate the development of low‐temperature ASSLSBs.

Optimizing cobalt/nickle sulfide heterojunction interface with ordered porous framework for efficient rechargeable zinc-air batteries

Developing efficient oxygen evolution/reduction reaction (OER/ORR) bifunctional catalysts is essential to improve zinc-air batteries (ZABs) performance. In this study, an OER/ORR bifunctional catalyst consists of cobalt and nickel sulfide heterojunction with three-dimensional ordered mesoporous structure is fabricated (3DOM Co9S8/Ni3S4). In-situ attenuated total reflection Fourier transform infrared tests and theoretical calculations reveal that the heterojunction structure promotes electrons transfer from Co9S8 to Ni3S4 and modulates the d-band center, thus optimizing the adsorption/desorption of *OH, *O and *OOH oxygen-containing intermediates and contributing to the improvement of the reactivity of the catalyst. In-situ Raman analysis shows that 3DOM Co9S8/Ni3S4 undergoes surface reconstruction to form highly reactive NiOOH species during the OER process. Meanwhile, the 3DOM framework structure also increases the catalyst specific surface area and benefits the mass transfer process during the reactions. As a result, 3DOM Co9S8/Ni3S4 exhibits a low OER overpotential (334 mV) at 10 mA cm−2 and the ORR half-wave potential is 0.77 V vs. RHE. The rechargeable ZABs with 3DOM Co9S8/Ni3S4 cathode deliver an energy density of 760.73 mAh g−1 at 10 mA cm−2 and stable cycling performance for 100 hours. This study provides guidance for developing efficient heterojunction bifunctional catalysts for ZABs.

Perceived Negative Menstrual Cycle Symptoms, but not Changes in Estrogen or Progesterone, are Associated with Impaired Cycling Race Performance.

Purpose: To examine the relationship between menstrual cycle (MC) phase-dependent fluctuations of estrogen and progesterone and virtual cycling race performance, with a secondary aim of correlating perceived MC-related symptoms with performance.Methods: In a novel observational study design, thirty-seven female cyclists/triathletes not using any hormonal contraception completed one virtual cycling race [19.5 km time trial (TT)] per week across a one-month period (totaling four races). Participants completed MC characterization and tracking, including urinary ovulation kits, across two complete MCs. Venous blood samples were collected within 21 h of racing to determine serum 17-β-estradiol and progesterone concentrations, as well as an assessment of self-reported, perceived race-day MC and gastrointestinal (GI) symptoms, which were all then correlated to race performance.Results: There was no relationship between race completion time and individual estradiol (r = -0.001, p = 0.992) or progesterone (r = -0.023, p = 0.833) concentrations. There was no difference between race time between MC phases (follicular/luteal, p = 0.238), whether MC bleeding or not bleeding (p = 0.619) and ovulating or not ovulating (p = 0.423). The total number of perceived MC symptoms recorded on race day was positively correlated to increased race time [r = 0.268 (95% CI 0.056 to 0.457), p = 0.014], as was the number of GI symptoms of at least "moderate" severity before the race (r = 0.233 [95% CI 0.021 to 0.425], p = 0.031), but not post-race (r = 0.022, p = 0.841).Conclusions: When implementing a novel, virtual cycling race, fluctuations in ovarian hormone concentrations across the MC do not appear to affect real-world cycling performance among trained cyclists, while perceived negative MC and GI symptoms may relate to impaired performance. Therefore, the management of negative MC and GI symptoms appears important for athletic performance enhancement or to mitigate performance decline.