The electrochemical performance of NaCrO2 as a positive electrode material for an intermediate-temperature sodium secondary battery was evaluated in an inorganic ionic liquid, NaFSA–KFSA ...(FSA = bis(fluorosulfonyl)amide), at 363 K. The positive electrode using NaCrO2, acetylene black, and polytetrafluoroethylene exhibited a stable discharge capacity of 113 mA h g−1 at a current density of 125 mA g−1. The Coulombic efficiency and the capacity retention at the 100th cycle were 99.6% and 98.5%, respectively. Even at the very high current density of 2000 mA g−1, the discharge capacity was maintained at 63 mA h g−1. X-ray diffraction analyses revealed that the deintercalation of Na+ ion from NaCrO2 was associated with several phase transitions in the following sequence: rhombohedral O3, monoclinic O′3, and monoclinic P′3.
► The performance of NaCrO2 positive electrode was evaluated at 363 K. ► NaFSA–KFSA was used as an intermediate temperature inorganic electrolyte. ► The phase transition behavior of NaCrO2 during desodiation was clarified. ► The phase transition occurred more readily at 363 K compared to room temperature. ► The reaction kinetics was enhanced at 363 K, giving the improved rate capability.
The electrochemical performance of a Na2FeP2O7 positive electrode has been evaluated in an inorganic ionic liquid NaFSAaKFSA (FSA = bis(fluorosulfonyl)amide) at 363 K. The electrode delivers a ...reversible capacity of 91 mAh ga1 with excellent rate capability (59 mAh ga1 at 2000 mA ga1) and a capacity retention of 91% over 1000 cycles, which facilitates the development of low-cost and high-safety sodium secondary batteries for large-scale energy storage applications. The average oxidation state of iron increases upon sodium extraction, as evidenced by the edge shift of an X-ray absorption spectroscopy analysis. According to an extended X-ray absorption fine structure analysis, the sodium extraction is accompanied by a shortening of FeaO bonds.
Developing highly efficient catalyst systems to transform lignin biomass into value‐added chemical feedstocks is imperative for utilizing lignin as renewable alternatives to fossil fuels. Recently, ...the pre‐activated strategy involving the selective oxidation of Cα alcohol of lignin substrates containing (β‐O‐4 linkage mode has been demonstrated to significantly increase the depolymerization efficiency of native aspen lignin from 10–20 to 60 wt.‐%. In this study, we reported the synthesis of a dinuclear oxovanadium complex 2 that is capable of selectively oxidizing the Cα alcohol (80 – 100% selectivity) of various dimeric lignin substrates under a mild condition. Further investigation of catalytic mechanism has revealed that two V=O motifs of complex 2 could serve as proton ion sites for both Cα and Cγ alcohol of dimeric lignin substrates, respectively. Interestingly, the dinuclear vanadium intermediate 4 demonstrates the ability to uptake two electrons resulting from the oxidation of Cα alcohol and yields two corresponding mononuclear VIV intermediate 5. The mononuclear VIV intermediate 5 exhibits a characteristic 8‐line EPR spectrum and possesses one unpaired electron determined by the Evans method. The established structure‐reactivity relationships will be able to shed light on the future directions for rational design of highly efficient catalysts for selective oxidation of lignin biomass.
The dinuclear oxovanadium molecular catalyst reported exhibits a highly selective secondary Cα aromatic alcohol oxidation (> 85% selectivity) of lignin substrates using air (1 atm) as an oxidant, with pyridine as additive. The excellent selectivity is attributed to the dinuclear nature of the catalyst facilitating two‐electron redox shuffling between VV‐VV and VIV‐VIV redox couples.
Understanding the electrochemical behavior and controlling the morphological variations of electrodes are critical for the design of high-capacity batteries. In this article, we describe a newly ...established operando scanning electron microscopy (SEM) to visualize the battery reactions in a modified coin cell, which allowed the simultaneous collection of electrochemical data and time-resolved images. The investigated silicon (Si)–polyimide-binder electrode exhibited a high capacity (∼1500 mAh g–1) and a desirable cyclability. Operando SEM revealed that the morphology of the Si anode drastically changed and cracks formed on the electrode because of the lithiation-induced volume expansion of the Si particles during the first charge process. Interestingly, the thickness variation in the Si composite layer was moderated in subsequent cycles. This strongly suggested that cracking caused by the breakage of the stiff binder alleviated the internal stress experienced by Si. On the basis of this finding by the operando SEM technique, patterned Si electrodes with controlled spacing were successfully fabricated, and their improved performance was confirmed.
Low-cost graphene nanoplatelet-polysulfone composite cathodes for a rechargeable aluminum battery with a Lewis acidic AlCl3–1-ethyl-3-methylimidazolioum chloride (C2mimCl) ionic liquid are prepared ...by a standard slurry-coating method for the composite electrode, and conductive additives such as acetylene black (AB), ketjen black (KB), and vapor grown carbon fiber (VGCF) are explored in order to improve the cathode performance. All the cathodes show reversible electrode reactions related to the intercalation reaction of AlCl4− into the graphene nanoplatelets. The cathodes achieve a discharge capacity of ca. 70–80 mAh g−1 at 1000 mA g−1. However, the rate capability and the capacity retention rate strongly depend on the conductive additive species. The best cathode performance is obtained when the additive is an equal mixture of VGCF and KB. The specific capacity is ca. 55 mAh g−1 at 10000 mA g−1. The retention rate based on the capacity observed at 1000 mA g−1 exceeds 65%. A Ragone plot constructed from the data shown in this article suggests that an Al rechargeable battery with a VGCF-KB added graphene nanoplatelet-polysulfone composite cathode has great potential as a future high-power density rechargeable battery.
Rechargeable aqueous zinc batteries (RAZBs) are emerging candidates for large‐scale energy storage. However, the lack of high‐capacity cathodes because of the electrostatic interactions between Zn
2+
...and cathode and the inferior electronic conductivity restricts their performance. The operating voltage limitation imposed by water is another barrier for RAZBs. Herein, manganese oxide (MnO) nanocrystals embedded in a spindle carbon matrix (MnO@C) synthesized from a metal–organic framework are used as a cathode. The uniform distribution of fine‐sized MnO (≈100 nm) in the carbonized matrix (≈5 μm) and the intimate connection between them not only increase the utilization of electroactive material but also eliminate the use of conductive additive. By utilizing the molten hydrate electrolyte, ZnCl
2
·2.33H
2
O, a discharge voltage plateau approaching 1.60 V and a high reversible capacity of 106 mAh g
−1
after 200 cycles are achieved. This research proposes an approach for affordable RAZBs to fulfill large‐scale energy storage.
Adenomyosis is an oestrogen‐dependent disease characterized by the invasion of endometrial epithelial cells into the myometrium of uterus, and angiogenesis is thought to be required for the ...implantation of endometrial glandular tissues during the adenomyotic pathogenesis. In this study, we demonstrate that compared with eutopic endometria, adenomyotic lesions exhibited increased vascularity as detected by sonography. Microscopically, the lesions also exhibited an oestrogen‐associated elevation of microvascular density and VEGF expression in endometrial epithelial cells. We previously reported that oestrogen‐induced Slug expression was critical for endometrial epithelial–mesenchymal transition and development of adenomyosis. Our present studies demonstrated that estradiol (E2) elicited a Slug‐VEGF axis in endometrial epithelial cells, and also induced pro‐angiogenic activity in vascular endothelial cells. The antagonizing agents against E2 or VEGF suppressed endothelial cells migration and tubal formation. Animal experiments furthermore confirmed that blockage of E2 or VEGF was efficient to attenuate the implantation of adenomyotic lesions. These results highlight the importance of oestrogen‐induced angiogenesis in adenomyosis development and provide a potential strategy for treating adenomyosis through intercepting the E2‐Slug‐VEGF pathway.
A local contact patterning process based on dewetting of 50 nm-thick polystyrene (PS) films has been developed for fabrication of silicon PERC (Passivated Emitter and Rear Cell) solar cells. Holey PS ...films with a random pattern of holes were prepared on dielectric passivated silicon wafers through the dewetting process, and then served as etch masks for selective plasma etching of dielectric passivation layers, in doing so metal contact patterns could be generated. The impact of local back contact formation on cell performance was studied as a function of the metallization fraction. This chemical-based patterning process, which broadens the applications of dewetting of polymer films, offers an interesting alternative to laser-based approaches as it may avoid silicon surface damage and lower the manufacturing costs. The application of this patterning technique to PERC fabrication could result in a preliminary efficiency of 13.5% with a
= 655 mV and a
= 38.4 mA cm
. An apparent gain in conversion efficiency of 0.6% could be achieved compared to the full-area aluminum back surface field reference cell.
The development of an aluminum secondary battery based on an Al metal anode, a graphene nanoplatelet composite cathode, and a Lewis acidic AlCl3–1-ethyl-3-methylimidazolium chloride ionic liquid ...electrolyte is demonstrated. Low-cost composite cathodes comprising only commercially available components are prepared by a standard slurry-coating method, and the cathodes exhibit a reversible capacity reaching 70 mAh g–1 (per graphene nanoplatelet weight) at a current density of 2000 mA g–1 and a good rate capability (∼66% capacity retention at 6000 mA g–1). A notable cyclability of up to 3000 cycles with a Coulombic efficiency approaching 99% is also obtained at 2000 mA g–1.
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