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.

Hybrid Solar Cells from Aqueous Polymers and Colloidal Nanocrystals

Recently,photovoltaic devices based on aqueous materials are drawing more and more attentions following the green chemistry concept.This review aims to present a general overview of polymer-nanocrystal hybrid photovoltaic devices based on aqueous materials.First,all-organic polymer solar cells based on water-soluble polymers as the active layer are briefly introduced.After that,we focus on the recent development of hybrid solar cells from aqueous polymers and colloidal nanocrystals.Finally,the remaining part of this review is focused on the challenges and proposed solutions associated with the aqueous-solution-processed hybrid solar cells.