ABSTRACT
The development of aqueous zinc-ion batteries (AZIBs) is hindered by dendrites and side reactions, such as interfacial byproducts, corrosion, and hydrogen evolution. The construction of an artificial interface protective layer on the surface of the zinc anode has been extensively researched due to its strong operability and potential for large-scale application. In this study, we have designed an organic hydrophobic hybrid inorganic intercalation composite coating to achieve stable Zn2+ plating/stripping. The hydrophobic poly(vinylidene fluoride) (PVDF) effectively prevents direct contact between free water and the zinc anode, thereby mitigating the risk of dendrite formation. Simultaneously, the inorganic layer of vanadium phosphate (VOPO4·2H2O) after the insertion of polyaniline (PA) establishes a robust ion channel for facilitating rapid transport of Zn2+, thus promoting uniform electric field distribution and reducing concentration polarization. As a result, the performance of the modified composite PVDF/PA-VOP@Zn anode exhibited significant enhancement compared with that of the bare zinc anode. The assembled symmetric cell exhibits an exceptionally prolonged lifespan of 3070 h at a current density of 1 mA cm-2, while the full battery employing KVO as the cathode demonstrates a remarkable capability to undergo 2000 cycles at 5 A g-1 with a capacity retention rate of 78.2%. This study offers valuable insights into the anodic modification strategy for AZIBs.
ABSTRACT
VO2 material, as a promising intercalation host, is widely investigated not only in aqueous lithium-ion batteries, but also in aqueous zinc-ion batteries (AZIBs) owing to its stable tunnel-like framework and multivalence of vanadium. Different from lithium-ion storage, VO2 can provide higher capacity when storing zinc ions, even exceeding its theoretical capacity (323 mAh g-1 ), but the specific reason for this unconventional performance in AZIBs is still unclear. The present study proposes a catalytic oxygen evolution reaction (OER) coupled with an interface oxidation mechanism of VO2 during the initial charging to a high voltage. This coupling induces a phase transformation of VO2 into a high oxidation state of V5 O12 â6H2 O, enabling a nearly two-electron reaction and providing additional zinc storage sites to achieve super-theoretical capacity. Furthermore, it is demonstrated that these vanadium oxide cathodes (V2 O3 , VO2 , and V2 O5 ) will all undergo phase change after the first charge or short cycle. Notably, water molecules participate in the final formation of layered vanadium-based hydrate, highlighting their crucial role as "pillars" for stabilizing the structure. This work significantly enhances the understanding of vanadium-based oxide cathodes.
ABSTRACT
The research on aqueous iron-ion batteries (AIIBs) is still in its early stages and highly limited by the lack of suitable cathode materials. In this study, we propose using tunnel-like VO2 as a cathode material, which delivers a high capacity of 198 mA h g-1 at 0.2 A g-1. Besides, the AIIB exhibits appreciable cycling performance, retaining 78.9% of its initial capacity after 200 cycles. The unique structure of VO2 and the multiple valence states of vanadium in VO2 enable the reversible storage of Fe2+ during cycling. This work presents a new choice for the cathode and considerable development prospects in AIIBs.
Subject(s)
Electric Power Supplies , Iron , Electrodes , Ions , VanadiumABSTRACT
OBJECTIVE: Explore the effect of the multifunctional airbag abdominal pressure belt on midwifery and on the prevention of postpartum hemorrhage. METHODS: Select 363 natural delivery cases of hospitalized primiparae and divide them randomly into two groups. In the observation group, 182 primiparae used the multifunctional airbag abdominal pressure belt during the second and third stages of labor, whereas the control group of 181 did not use the belt. Delivery outcomes of the primiparae and their fetus were then observed. RESULTS: The average duration for the second stage of labor, from head emergence to delivery, placenta delivery and postpartum hemorrhage were all shorter in the observation group (p < 0.01). There was no statistical difference in episiotomy rate, maternal signs 2 h postpartum, neonatal Apgar score and neonatal cord blood gas analysis (p > 0.05). No statistical difference was found in primipara signs and no fetal heart rate change of the primiparae under different internal pressures of the belt during the second stage of labor in the observation group (p > 0.05). CONCLUSION: By closely monitoring and appropriately adjusting the internal pressure of the belt, the multifunctional airbag abdominal pressure belt can speed up the second and third stages of labor, prevent postpartum hemorrhage and promote natural delivery.
