Uniform zinc-ion deposition regulated by thin sulfonated poly(ether ketone) layer for Stabilizing Zn anodes.

Aqueous zinc-ion batteries (AZIBs) have been getting lots of attention in the field of large scale energy storage owing to their low cost, large capacity and excellent safety. However, Zn anodes have serious dendritic growth and corrosion hydrogen evolution issues, which hinder their further application. Herein, a simple drop-coating technique was used to build a thin sulfate poly(ether ketone) (SPEEK) solid-electrolyte interphase (SEI) on the surface of the Zn anode to address these issues. The sulfonated group (-SO3-） in SPEEK can provide rich coordination sites for Zn2+, controlling the uniform deposition of Zn2+. Therefore, the polymer SEI can block electrolytes and homogenize the Zn2+flux, resulting that the modified Zn (SPEEK@Zn) anode could effectively limit the formation of dendrites and side reactions. At a current density of 0.5 mA cm-2, SPEEK@Zn electrodes can maintain an ultra-long plating/stripping cycle life of 1000 h. Full batteries based on SPEEK@Zn have more superior cycle stability than the bare ones. This approach offers a straightforward and scalable remedy for high-performance Zn anode batteries.

Recent Advances for Electrode Modifications in Flow Batteries: Properties, Mechanisms, and Outlooks.

Flow batteries (FBs) have been demonstrated in several large-scale energy storage projects, and are considered to be the preferred technique for large-scale long-term energy storage in terms of their high safety, environmental friendliness, and long life, including all-vanadium flow batteries (VFBs) and Fe-Cr flow batteries (ICFBs). As the electrochemical reaction site, the electrode parameters, such as the specific surface area, active site, and so on, have a significant impact on the flow battery performance and reliability. Extensive research has been carried out on electrode modification to improve the current density and energy efficiency of the FBs. In this review, the reaction mechanisms of VFBs and ICFBs are discussed in detail firstly, and then the electrodes modification methods are overviewed and summarized from four aspects: self-modification, carbon-based electrocatalysts, metal-based electrocatalysts and composite electrocatalysts. Finally, the recent catalytic mechanism, in situ characterization technology, and future research directions are presented.

Boosting the Areal Capacity of Titanium-Manganese Single Flow Battery by Fe2+ /Fe3+ Redox Mediator.

Aqueous manganese-based flow batteries (AMFBs) have attracted great attention due to the advantages of low cost and environmental friendliness. Extending the cycle life of AMFBs has long been a challenging theme. The titanium-manganese single-flow batteries (TMSFB) are promising due to their special structure and electrolyte composition. However, TMSFB with high areal capacity faces capacity decay for unknown reasons. In this work, the capacity decay mechanism (accumulation and growth of MnO2 ) is clarified by a homemade in situ microscope system. Given that, a redox mediator of Fe2+ /Fe3+ is specially designed to boost the areal capacity of TMSFB without side reaction. The directional promoting principle of the Fe2+ /Fe3+ is elaborated in detail. Fe2+ chemically reacts with the residual MnO2 to form Fe3+ , which is reduced to Fe2+ by the electrochemical reaction. And then Fe2+ continues reacting with MnO2 until MnO2 is consumed completely. As a result, the TMSFB with the areal capacity of ≈55 mA h cm-2 can stably operate at a current density of 40 mA cm-2 , which is the highest areal capacity reported in aqueous manganese-based batteries. This work provides a new strategy for boosting the capacity of manganese-based batteries, shedding light on the improvement of other deposition-type batteries.

Electrical-Conductive/Insulating Bi-Functional Layers for Stable Zn Metal Anode.

Zinc-ion batteries are regarded as an extremely promising candidate for large-scale energy storage equipment due to the inexpensive ingredients and high safety. However, dendrite growth and side reactions occur in the Zn anode, which lead to exceedingly low coulombic efficiency (CE) and poor cycling stability. In this work, we propose a strategy of a conductive/insulating bi-functional coating layer (CIBL) for stable Zn metal anodes. Porous Ag nanowires (NWs) coating as a conductive layer effectively reduces the nuclear barrier and contains Zn2+ deposition in a certain space. Polyimide (PI) coatings as insulating layer implement a shunting effect on Zn2+ , which could reduce the differential concentration on the Zn surface and induce uniform deposition of Zn2+ . Therefore, the CIBL-Zn//CIBL-Zn battery achieves stable plating/stripping of over 1300 h at 1 mA cm-2 . The CE of CIBL-Zn//CIBL-Zn battery maintains at 99.2 % even after 1000 cycles. Moreover, the CIBL-Zn//V2 O5 battery exhibits a capacity of nearly 289.2 mA h g-1 at 5 A g-1 after 3000 cycles and no sign of capacity degradation is found, which further demonstrate the feasibility of this strategy in practical application.

A Composite Membrane with High Stability and Low Cost Specifically for Iron-Chromium Flow Battery.

The iron-chromium flow battery (ICFB), the earliest flow battery, shows promise for large-scale energy storage due to its low cost and inherent safety. However, there is no specific membrane designed that meets the special requirements of ICFBs. To match the harsh operation parameters of ICFBs, we designed and fabricated a composite membrane with high mechanical, chemical, and thermal stability. In the design, a commercial porous polyethylene membrane is selected as the framework material, offering high mechanical stability and reducing the cost. Meanwhile, the Nafion resin is filled in the pores of a porous membrane, which inhibits the transfer of redox-active ions and creates the proton channels via hydrophobic/hydrophilic phase separation. As a result, the composite membrane exhibits high conductivity, selectivity, and stability, especially with almost no swelling at high operating temperatures. Thus, an ICFB with the prepared membrane exhibits a coulombic efficiency of 93.29% at the current density of 80 mA cm-2 and runs stably for over 300 cycles. This work provides an easy method to fabricate high-performance and low-cost membranes specifically for ICFBs and has the potential to promote the development of ICFBs.

The Application of a Modified Polyacrylonitrile Porous Membrane in Vanadium Flow Battery.

Vanadium flow battery (VFB) is one of the most promising candidates for large-scale energy storage. A modified polyacrylonitrile (PAN) porous membrane is successfully applied in VFB. Herein, a simple solvent post-processing method is presented to modify PAN porous membranes prepared by the traditional nonsolvent induced phase separation (NIPS) method. In the design, polymer PAN is chosen as the membrane material owing to its low cost and high stability. The large-size pores from NIPS method are well optimized by the solvent swelling and shrinking during the solvent post-processing. Meanwhile, the interconnectivity of pores is maintained well. As a result, the ion selectivity of PAN porous membranes is dramatically improved, and the CE of a VFB with PAN porous membranes rises from 68% to 93% after the solvent post-processing process. A VFB with the modified PAN porous membranes is capable of delivering a limiting current density of 900 mA cm-2, and a high peak power density of 650 mW cm-2, which is very competitive among the various flow batteries.

Comparison of physical condition of middle school students of Lahu nationality in 2014 and 2019 / 中国学校卫生

Objective@#To gain a better understanding of the status quo of the physical condition of students in Lahu Nationality Middle School, so as to provide a basis for intervention measures to improve students’ physical health.@*Methods@#A comparative analysis on the data of the physique investigation of the students in Lahu nationality middle school in 2019 and 2014 was carried out.@*Results@#Compared with 2014, in 2019, the BMI of the males except aged 13 increased by 0.45 kg/m2, there was no statistically significant difference in the BMI of other age groups aged(P>0.05). In 2019, there was no statistically significant difference in the BMI of females aged 13 to 18 compared with 2014(P>0.05). The vital capacity/BMI respectively increased by 3.74 and 3.99 mL/kg in males aged 13 and 15, and the differences were statistically significant(t=2.36, 2.05, P<0.05). In 2019, the vital capacity/BMI of females aged 14-15 increased by 3.18, 3.64 mL/kg, respectively; the vital capacity/BMI of females aged 16 decreased by 2.50 mL/kg, the difference was statistically significant(P<0.05). For males aged 13-18 of the Lahu nationality and compared with 2014, in the 50m race, except that those aged 15, there was no statistically significant difference in the race time in other age groups(P>0.05); there was no statistically significant difference in the sit and reach of males aged 13 to 18(P>0.05); the males aged 14 was 20.52 s faster in the 1 000 m race, while those aged 17-18 were respectively 21.04 and 19.10 s slower in the-1 000 m-race, pull-ups in those aged 13 increased by 1.32, and decreased by 0.96 and 1.32 in those aged 17-18, the standing long jump of those aged 13 to 16 and 18 increased by 18.90, 16.36, 36.27, 13.32, 8.55 cm, respectively; and the differences were statistically significant(P<0.01). For females aged 13-18 of the Lahu nationality and compared with 2014, in the 50 m race, there was no statistically significant difference in the race time in those aged 13-18(P>0.05); the sit and reach of those aged 14-15 increased by 2.38 and 2.96 cm, respectively; the females aged 13-15 was 15.15, 14.48, 15.65 s faster in the 800 m race, respectively; while those aged 16-17 were respectively 18.16 and 10.74 s slower in the 800 m race; pull-ups in those aged 13-15 and 17-18 increased by 5.58, 6.97, 5.34, 2.04, 2.64, respectively; the standing long jump of those aged 13-18 increased by 14.75, 17.10, 14.76, 8.22, 10.47, 8.36 cm, respectively; and the differences were statistically significant(P<0.01).@*Conclusion@#The physical condition of middle school students in Lahu Nationality generally shows a slow-increasing trend, the physical shape of the male students presents an upward trend, and the physical fitness students shows a positive trend, albeit featured in imbalanced development. According to the problems existing in the physical development of the students in Lahu nationality, effective intervention measures should be taken to elevate the physical health condition of middle school students in Lahu nationality.