Pyrethroids are increasingly receiving attention as aqueous micropollutants, but their presence has been reported only in a few small coastal areas. In this study, we investigated the distribution, ...sources, and risks of nine pyrethroids in large marine zones. The 40 seawater samples were collected from the South Yellow Sea (SYS) and East China Sea (ECS) in China, during the spring of 2020, using a high-volume, solid-phase extraction method. The total pyrethroid concentrations ranged from 0.72 to 1.82 ng L−1 in the SYS and from 0.02 to 11.0 ng L−1 in the ECS. We used cluster analysis to classify pollutant sources into five categories, and discussed the influence of sources on the transport and distribution of pyrethroids in each group. Ecological risk assessment indicated that pyrethroids pose a high risk to crustaceans and a negligible risk to others. These results are important for understanding the behavior of pyrethroids in marine environments.
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•Efficient Hi-throat/Hi-volume SPE was used to concentrate pyrethroids from seawater.•Occurrence of nine pyrethroids was investigated at South Yellow and East China Seas.•Distribution and sources are influenced by both human activities and ocean currents.•Ecological risk assessment indicated that pyrethroids pose a high risk to crustaceans.
High‐temperature‐induced fire is an extremely serious safety risk in energy storage devices; which can be avoided by replacing their components with nonflammable materials. However; these devices are ...still destroyed by the high‐temperature decomposition; lacking reliability. Here, a fire‐tolerant supercapacitor is further demonstrated that recovers after burning with a self‐healable “solute‐in‐air” electrolyte. Using fire‐tolerant electrodes and separator with a semiopen device configuration; hygroscopic CaCl2 in the air (“CaCl2‐in‐air”) is designed as a self‐healable electrolyte; which loses its water solvent at high temperatures but spontaneously absorbs water from the air to recover by itself at low temperatures. The supercapacitor is disenabled at 500 °C; while it recovers after cooling in the air. Especially; it even recovers after burning at around 647 °C with enhanced performance. The study offers a self‐healing strategy to design high‐safety; high‐reliability; and fire‐tolerant supercapacitors; which inspires a promising way to deal with general fire‐related risks.
Hygroscopic chemistry enables fire‐tolerant supercapacitors with a self‐healable “solute‐in‐air” electrolyte. High‐temperature‐induced fire is a common safety risk that is extremely serious in energy storage devices. Here, a fire‐tolerant supercapacitor achieved by the self‐healable “solute‐in‐air” electrolyte is reported, in which hygroscopic solute spontaneously absorbs water from the air as the solvent to recover the disenabled supercapacitor even after burning.
Thermal safety issues of batteries have hindered their large‐scale applications. Nonflammable electrolytes improved safety but solvent evaporation above 100 °C limited thermal tolerance, lacking ...reliability. Herein, fire‐tolerant metal‐air batteries were realized by introducing solute‐in‐air electrolytes whose hygroscopic solutes could spontaneously reabsorb the evaporated water solvent. Using Zn/CaCl2‐in‐air/carbon batteries as a proof‐of‐concept, they failed upon burning at 631.8 °C but self‐recovered then by reabsorbing water from the air at room temperature. Different from conventional aqueous electrolytes whose irreversible thermal transformation is determined by the boiling points of solvents, solute‐in‐air electrolytes make this transformation determined by the much higher decomposition temperature of solutes. It was found that stronger intramolecular bonds instead of intermolecular (van der Waals) interactions were strongly correlated to ultra‐high tolerance temperatures of our solute‐in‐air electrolytes, inspiring a concept of non‐van der Waals electrolytes. Our study would improve the understanding of the thermal properties of electrolytes, guide the design of solute‐in‐air electrolytes, and enhance battery safety.
While the irreversible thermal transformation of electrolytes is typically attributed to solvent boiling, which disrupts solvent intermolecular interactions, our research revealed that hygroscopic solutes shift the determining factor to solute decomposition, breaking solute intramolecular bonds. As intramolecular bonds are much stronger, it enables ultrahigh thermal tolerance of non‐van der Waals solute‐in‐air electrolytes.
Solute‐in‐air electrolytes are applied in metal‐air batteries, introducing dual‐air batteries for intrinsic safe energy storage. In their Research Article (e202318369), Xiaodong Chen and co‐workers ...demonstrate that fire‐tolerant batteries are achieved, and reveal that the highest tolerance temperature of electrolytes is determined by solute intramolecular bonds instead of solvent intermolecular interactions, inspiring a concept of non‐van der Waals electrolytes for their thermal stability.
Rapid charging capability is a requisite feature of lithium-ion batteries (LIBs). To overcome the capacity degradation from a steep Li-ion concentration gradient during the fast reaction, electrodes ...with tailored transport kinetics have been explored by managing the geometries. However, the traditional electrode fabrication process has great challenges in precisely controlling and implementing the desired pore networks and configuration of electrode materials. Herein, we demonstrate a density-graded composite electrode that arises from a three-dimensional current collector in which the porosity gradually decreases to 53.8% along the depth direction. The density-graded electrode effectively reduces energy loss at high charging rates by mitigating polarization. This electrode shows an outstanding capacity of 94.2 mAh g–1 at a fast current density of 59.7 C (20 A g–1), which is much higher than that of an electrode with a nearly constant density gradient (38.0 mAh g–1). Through these in-depth studies on the pore networks and their transport kinetics, we describe the design principle of rational electrode geometries for ultrafast charging LIBs.
MoS2 holds great promise as high‐rate electrode for lithium‐ion batteries since its large interlayer can allow fast lithium diffusion in 3.0–1.0 V. However, the low theoretical capacity (167 mAh g−1) ...limits its wide application. Here, by fine tuning the lithiation depth of MoS2, we demonstrate that its parent layered structure can be preserved with expanded interlayers while cycling in 3.0–0.6 V. The deeper lithiation and maintained crystalline structure endows commercially micrometer‐sized MoS2 with a capacity of 232 mAh g−1 at 0.05 A g−1 and circa 92 % capacity retention after 1000 cycles at 1.0 A g−1. Moreover, the enlarged interlayers enable MoS2 to release a capacity of 165 mAh g−1 at 5.0 A g−1, which is double the capacity obtained under 3.0–1.0 V at the same rate. Our strategy of controlling the lithiation depth of MoS2 to avoid fracture ushers in new possibilities to enhance the lithium storage of layered transition‐metal dichalcogenides.
By fine‐tuning the lithiation depth of MoS2, the layered crystalline structure can be well preserved when cycled (3.0–0.6 V vs. Li+/Li), which is accompanied with the expansion of the interlayer distance. These features enable the stable cycling of commercial μm‐sized MoS2 with higher capacity and faster rate capability, making it a promising anode for fast‐charging lithium ion batteries.
Flexible lithium‐ion batteries (LIBs) with high energy density are highly desirable for wearable electronics. However, difficult to achieve excellent flexibility and high energy density ...simultaneously via the current approaches for designing flexible LIBs. To mitigate the mismatch, mechano‐graded electrodes with gradient‐distributed maximum allowable strain are proposed to endow high‐loading‐mass slurry‐coating electrodes with brilliant intrinsic flexibility without sacrificing energy density. As a proof‐of‐concept, the up‐graded LiNi1/3Mn1/3Co1/3O2 cathodes (≈15 mg cm−2, ≈70 µm) and graphite anodes (≈8 mg cm−2, ≈105 µm) can tolerate an extremely low bending radius of 400 and 600 µm, respectively. Finite element analysis (FEA) reveals that, compared with conventionally homogeneous electrodes, the flexibility of the up‐graded electrodes is enhanced by specifically strengthening the upper layer and avoiding crack initiation. Benefiting from this, the foldable pouch cell (required bending radius of ≈600 µm) successfully realizes a remarkable figure of merit (FOM, energy density vs bending radius) of 121.3 mWh cm−3. Moreover, the up‐graded‐electrodes‐based pouch cells can deliver a stable power supply, even under various deformation modes, such as twisting, folding, and knotting. This work proposes new insights for harmonizing the mechanics and electrochemistry of energy storage devices to achieve high energy density under flexible extremes.
Mechano‐graded electrodes with gradient‐distributed maximum allowable strain are proposed to mitigate the mismatch between mechanical reliability and energy density for high‐energy‐density flexible lithium‐ion batteries (LIBs). The up‐graded‐electrode‐based LIBs enable a remarkable figure of merit (FOM) value of 121.3 mWh cm−3, proving the brilliant comprehensive performance of flexible high‐energy‐density LIBs.
MoS
holds great promise as high-rate electrode for lithium-ion batteries since its large interlayer can allow fast lithium diffusion in 3.0-1.0 V. However, the low theoretical capacity (167 mAh g
) ...limits its wide application. Here, by fine tuning the lithiation depth of MoS
, we demonstrate that its parent layered structure can be preserved with expanded interlayers while cycling in 3.0-0.6 V. The deeper lithiation and maintained crystalline structure endows commercially micrometer-sized MoS
with a capacity of 232 mAh g
at 0.05 A g
and circa 92 % capacity retention after 1000 cycles at 1.0 A g
. Moreover, the enlarged interlayers enable MoS
to release a capacity of 165 mAh g
at 5.0 A g
, which is double the capacity obtained under 3.0-1.0 V at the same rate. Our strategy of controlling the lithiation depth of MoS
to avoid fracture ushers in new possibilities to enhance the lithium storage of layered transition-metal dichalcogenides.
Oxygen vacancies play crucial roles in defining physical and chemical properties of materials to enhance the performances in electronics, solar cells, catalysis, sensors, and energy conversion and ...storage. Conventional approaches to incorporate oxygen defects mainly rely on reducing the oxygen partial pressure for the removal of product to change the equilibrium position. However, directly affecting reactants to shift the reaction toward generating oxygen vacancies is lacking and to fill this blank in synthetic methodology is very challenging. Here, a strategy is demonstrated to create oxygen vacancies through making the reaction energetically more favorable via applying interfacial strain on reactants by coating, using TiO2(B) as a model system. Geometrical phase analysis and density functional theory simulations verify that the formation energy of oxygen vacancies is largely decreased under external strain. Benefiting from these, the obtained oxygen‐deficient TiO2(B) exhibits impressively high level of capacitive charge storage, e.g., ≈53% at 0.5 mV s−1, far surpassing the ≈31% of the unmodified counterpart. Meanwhile, the modified electrode shows significantly enhanced rate capability delivering a capacity of 112 mAh g−1 at 20 C (≈6.7 A g−1), ≈30% higher than air‐annealed TiO2 and comparable to vacuum‐calcined TiO2. This work heralds a new paradigm of mechanical manipulation of materials through interfacial control for rational defect engineering.
An atmosphere‐independent approach to incorporate oxygen vacancies into electrode is developed via applying interfacial lattice strain by oxide coating, using TiO2(B) as a model system. The obtained oxygen‐deficient electrode shows significantly enhanced pseudocapacitive charge storage and high rate capability, making this strategy very promising for high‐power energy‐storage applications.
•Differences and similarities between ice and aqueous photochemistry were revealed.•Photodegradation kinetics are clearly influenced by the matrix phases, ice and water.•Different photodegradable ...potential orders between in the two phases were discovered.•Unidentical effects of key constituents in the two phases account for the differences.•Ice photolysis shows fewer products / simpler pathways compared to water photolysis.
The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry. Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs, 2-hydroxyfluorene (2-OHFL) and 9-hydroxyfluorene (9-OHFL), which are newly recognized contaminants in the wider environment including colder regions. Interestingly, their photodegradation kinetics were clearly influenced by whether they reside in ice or water. Under the same simulated solar irradiation (λ > 290 nm), OHFLs photodegraded faster in ice than in equivalent aqueous solutions and this was attributed to the specific concentration effect caused by freezing. Furthermore, the presence of dissolved constituents in ice also influenced photodegradation with 2-OHFL phototransforming the fastest in ‘seawater’ ice (k = (11.4 ± 1.0) × 10−2 min−1) followed by ‘pure-water’ ice ((8.7 ± 0.4) × 10−2 min−1) and ‘freshwater’ ice ((8.0 ± 0.7) × 10−2 min−1). The presence of dissolved constituents (specifically Cl−, NO3−, Fe(III) and humic acid) influences the phototransformation kinetics, either enhancing or suppressing phototransformation, but this is based on the quantity of the constituent present in the matrixes, the specific OHFL isomer and the matrix type (e.g., ice or aqueous solution). Careful derivation of key photointermediates was undertaken in both ice and water samples using tandem mass spectrometry. Ice phototransformation exhibited fewer by-products and ‘simpler’ pathways giving rise to a range of hydroxylated fluorenes and hydroxylated fluorenones in ice. These results are of importance when considering the fate of PAHs and OH-PAHs in cold regions and their persistence in sunlit ice.
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