ZIF-7@carbon composites as multifunctional interlayer for rapid and durable Li-S performance

The notorious"shuttle effect"of polysulfide during charge-discharge process induces grievous capacity fading,while the sluggish polysulfide conversion kinetics significantly hinders the development of practically viable lithium-sulfur(Li-S)batteries.In this study,a novel ZIF-7@carbon composite with ZIF-7 sheets vertically rooted on carbon cloth was developed as multifunctional interlayer to address these issues.The composite shows directional layered structure with outstanding compactness,and thus can provide massive active sites for accelerated redox reactions.The pore channels are perpendicular to the square surface,resulting in extremely high utilization of one-dimensional channels.Therefore,this structure can not only maintain the structural stability during the charge-discharge process by providing enough space for volume expansion,but also contribute to efficient exposure and utilization of active sites for the physical/chemical adsorption and catalytic conversion of polysulfide.As a result,Li-S batteries with the as-developed interlayer deliver a considerable areal capacity of 4.75 mAh cm^(-2) at an elevated sulfur loading of 5.5 mg cm^(-2),and an impressive cyclability with an extremely low capacity-fading rate of merely 0.04%per cycle over 500 cycles at 1 C.

An orderly arranged dual-role MIL-53(Al)nanorods array rooted on carbon nanotube film for long-life and stable lithium-sulfur batteries

It is of great value to synchronously resolve the critical issues of the polysulfide shuttle and dendrite growth in lithium-sulfur(Li-S)batteries.Herein,a bifunctional Al-based Material of Institute Lavoisier-53(MIL-53(Al))/carbon nanotube(MIL-53/CNT)composite is reported for this matter,which was constructed by growing an ordered MIL-53(Al)nanorods array on the CNT film.For the sulfur cathode,the proposed structure serves as a multifunctional interlayer to block polysulfides and accelerate their catalytic conversion,thus efficaciously inhibiting the shuttle effect.Meanwhile,when applied as the anode host material(Li@MIL-53/CNT),the flexible CNT film serves as a self-standing framework to accommodate Li metal and alleviate the volume expansion,while the uniform ion channels built by the MIL-53(Al)nanorods array along with the abundant oxygen groups can homogenize Li ion diffusion,enabling a steady Li plating/stripping behavior and limiting the dendrite growth.Not surprisingly,Li-S full battery with MIL-53/CNT interlayer and Li@MIL-53/CNT anode delivers an appreciable specific capacity of 735 mAh·g^(–1)and excellent cycle durability at 5 C,presenting a limited capacity decay of 0.03%per cycle in 500 cycles.Besides,an impressive cycle stability and rate capability are also achieved at high-sulfur loading and lean electrolyte conditions.

Continuous amino-functionalized University of Oslo 66 membranes as efficacious polysulfide barriers for lithium−sulfur batteries

The shuttle effect of soluble polysulfides is a serious problem impeding the development of lithium−sulfur batteries.Herein,continuous amino-functionalized University of Oslo 66 membranes supported on carbon nanotube films are proposed as ion-permselective interlayers that overcome these issues and show outstanding suppression of the polysulfide shuttle effect.The proposed membrane material has appropriately sized pores,and can act as ionic sieves and serve as barriers to polysulfides transport while allowing the passage of lithium ions during electrochemical cycles,thereby validly preventing the shuttling of polysulfides.Moreover,a fast catalytic conversion of polysulfides is also achieved with the asdeveloped interlayer.Therefore,lithium−sulfur batteries with this interlayer show a desirable initial capacity of 999.21 mAh·g^(-1)at 1 C and a durable cyclic stability with a decay rate of only 0.04%per cycle over 300 cycles.Moreover,a high area capacity of 4.82 mAh·cm^(-2)is also obtained even under increased sulfur loading(5.12 mg·cm^(-2))and a lean-electrolyte condition(E/S=4.8μL·mg^(-1)).

Flow synthesis of a novel zirconium-based UiO-66 nanofiltration membrane and its performance in the removal of p-nitrophenol from water

In this work,a thin zirconium-based UiO-66 membrane was successfully prepared on an alumina hollow fiber tube by flow synthesis,and was used in an attempt to remove p-nitrophenol from water through a nanofiltration process.Two main factors,including flow rate and synthesis time,were investigated to optimize the conditions for membrane growth.Under optimal synthesis conditions,a thin UiO-66 membrane of approximately 2 um in thickness was fabricated at a flow rate of4 mL.h for 30 h.The p-nitrophenol rejection rate for the as-prepared UiO-66 membrane applied in the removal of p-nitrophenol from water was only 78.1%due to the existence of membrane defects caused by coordinative defects during membrane formation.Post-synthetic modification of the UiO-66 membrane was carried out using organic linkers with the same flow approach to further improve the nanofiltration performance.The result showed that the p-nitrophenol rejection for the post-modified membrane was greatly improved and reached over 95%.Moreover,the post-modified UiO-66 membrane exhibited remarkable long-term operational stability,which is vital for practical application.

Engineering zirconium-based metal-organic framework-801 films on carbon cloth as shuttle-inhibiting interlayers for lithium-sulfur batteries

Lithium-sulfur batteries have been regarded as the next-generation rechargeable batteries due to their high theoretical energy density and specific capacity.Nevertheless,the shuttle effect of lithium polysulfides has hindered the development of lithium-sulfur batteries.Herein,a novel zirconium-based metal-organic framework-801 film on carbon cloth was developed as a versatile interlayer for lithium-sulfur batteries.This interlayer has a hierarchical porous structure,suitable for the immobilization of lithium polysulfides and accommodating volume expansion on cycling.Moreover,the MOF-801 material is capable of strongly adsorbing lithium polysulfides and promoting their catalytic conversion,which can be enhanced by the abundant active sites provided by the continuous structure of the MOF-801 films.Based on the above advantages,the lithium-sulfur battery,with the proposed interlayer,delivers an initial discharge capacity of 927 mAh·g^(-1) at 1 C with an extremely low decay rate of 0.04%over 500 cycles.Additionally,a high area capacity of 4.3 mAh·cm^(-2) can be achieved under increased S loading.