Rational design and low-cost fabrication of multifunctional separators enabling high sulfur utilization in long-life lithium-sulfur batteries

The lithium-sulfur(Li-S)battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium polysulfides(LiPSs)intermediates that result in low sulfur utilization.The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utilization in Li-S batteries by achieving effective regulation of LiPSs.Herein,a promising self-assembly strategy is proposed to achieve the low-cost fabrication of hollow and hierarchically porous Fe_(3)O_(4)nanospheres(p-Fe_(3)O_(4)-NSs)assembled by numerous extremely-small primary nanocrystals as building blocks.The rationally-designed p-Fe_(3)O_(4)-NSs are utilized as a multifunctional layer on the separator with highly efficient trapping and conversion features toward LiPSs.Results demonstrate that the nanostructured p-Fe_(3)O_(4)-NSs provide chemical adsorption toward LiPSs and kinetically promote the mutual transformation between LiPSs and Li_(2)S_(2)/Li_(2)S during cycling,thus inhibiting the LiPSs shuttling and boosting the redox reaction kinetics via a chemisorption-catalytic conversion mechanism.The enhanced wettability of the p-Fe_(3)O_(4)-NSs-based separator with the electrolyte enables fast transportation of lithium ions.Benefitting from these alluring properties,the functionalized separator with p-Fe_(3)O_(4)-NSs endows the battery with an admirable rate performance of 877 mAh g^(−1)at 2 C,an ultra-durable cycling performance of up to 2176 cycles at 1 C,and a promising areal capacity of 4.55 mAh cm^(−2)under high-sulfur-loading and lean-electrolyte conditions(4.29 mg cm^(−2),electrolyte/ratio:8μl mg^(−1)).This study will offer fresh insights on the rational design and low-cost fabrication of multifunctional separator to strengthen electrochemical reaction kinetics by regulating LiPSs conversion for developing efficient and long-life Li-S batteries.

Review of blue perovskite light emitting diodes with optimization strategies for perovskite film and device structure

Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.

2023年度工程与材料科学部基金项目评审工作综述

本文总结了2023年度国家自然科学基金委员会工程与材料科学部项目评审工作情况,对各类项目申请、受理、评审和资助情况进行了整理及分析,重点回顾了本年度工程与材料科学部深化科学基金改革新举措及实施成效,并提出了下一年度评审工作的思路及建议,以进一步提高工程与材料科学基础研究资助质量。

2022年度工程与材料科学部基金项目评审工作综述

本文总结了2022年度国家自然科学基金委员会工程与材料科学部项目评审工作情况,对各类项目申请、受理、评审和资助情况进行了整理及分析,重点回顾了本年度工程与材料科学部深化科学基金改革新举措的实施情况,并提出了下一年度评审工作的思路及建议,以进一步提高工程与材料科学基础研究资助质量。

工程与材料科学部重大项目立项与管理机制改革探索及思考

国家自然科学基金重大项目是国家自然科学基金委员会(简称“自然科学基金委”)资助体系中重要的项目类型之一,在发挥学科支撑和引领作用、推动产生原创性重大成果方面具有重要战略地位。本文全面回顾并分析了工程与材料科学部重大项目资助现状,重点阐述了当前在立项与管理机制方面存在的一些问题,阐明了重大项目深化改革的必要性和紧迫性,介绍了自然科学基金委工程与材料科学部的具体改革思路和举措,以及进行的实践和探索,提出了一些思考,为新时期国家自然科学基金重大项目深化改革提供了重要参考。

Enhanced optical and thermal performance of white light-emitting diodes with horizontally layered quantum dots phosphor nanocomposites

Due to their good color rendering ability, white light-emitting diodes(WLEDs) with conventional phosphor and quantum dots(QDs) are gaining increasing attention. However, their optical and thermal performances are still limited especially for the ones with QDs-phosphor mixed nanocomposites. In this work, we propose a novel packaging scheme with horizontally layered QDs-phosphor nanocomposites to obtain an enhanced optical and thermal performance for WLEDs. Three different WLEDs, including QDs-phosphor mixed type, QDsoutside type, and QDs-inside type, were fabricated and compared. With 30 wt. % phosphor and 0.15 wt. % QDs nanocomposite, the QDs-outside type WLED shows a 21.8% increase of luminous efficiency, better color rendering ability, and a 27.0% decrease of the maximum nanocomposite temperature at 400 mA, compared with the mixed-type WLED. The reduced re-absorption between phosphor and QDs is responsible for the performance enhancement when they are separated. However, such reduced absorption can be traded off by the improper layered configuration, which is demonstrated by the worst performance of the QDs-inside type. Further, we demonstrate that the higher energy transfer efficiency between excitation light and nanocomposite in the QDs-outside type WLED is the key reason for its enhanced optical and thermal performance.

Plowing-Extrusion Processes and Performance of Functional Surface Structures of Copper Current Collectors for Lithium-Ion Batteries

Most copper current collectors for commercial lithium-ion batteries(LIBs)are smooth copper foils,which cannot form a stable and effective combination with electrode slurry.They are likely to deform or fall off after long-term operation,resulting in a sharp decline in battery performance.What is worse is that this condition inevitably causes internal short circuits and thus brings about security risks.In this study,a process route of fabricating the functional surface structures on the surface of a copper collector for LIBs by twice-crisscross micro-plowing(TCMP)is proposed,which provides a new idea and an efficient method to solve the above problems from the perspective of manufacturing.The finite element simulation of TCMP combined with the cutting force test and morphological characterization is conducted to verify the forming mechanism of the surface structures on a copper sheet and its relationship with the processing parameters.The influence of several key processing parameters on the surface characteristics of the copper sheet is comprehensively explored.A series of functions is tested to obtain the optimal parameters for performance improvement of the current collector.Results show that the structured copper sheet with the cutting distance of 250μm,cutting depth of 80μm,and cutting crossing angle of 90°enables the best surface features of the current collector;the contact angle reaches 0°,the slurry retention rate is up to 89.2%,and the friction coefficient reaches 0.074.The battery using the as-prepared structured copper sheet as the current collector produces a specific capacity of 318.6 mAh/g after 50 cycles at a current density of 0.2 C,which is 132.7%higher than the one based on a smooth surface.The capacity reversibility of the sample with the new current collector is much better than that of the traditional samples,yielding a lower impedance.

Water-stable CsPbBr3 perovskite quantum-dot luminous fibers fabricated by centrifugal spinning for dual white light illumination and communication

Lead halide perovskite quantum dots(PQDs)display remarkable photoelectric performance.However,defects such as weak stability in air and water environments limit the development of lead halide PQDs in solid-state light applications.Herein,centrifugal spinning is used for the fabrication of stable luminous CsPbBr3 PQD nanofibers.After immersion in water for 11 months,the PQD fibers still maintained considerable photoluminescence quantum yield,showing high stability in hostile environments.The water-stability mechanism of the fibers can be explained by the changing defect density,crystal growth of PQDs,and the molecular transformation at the fiber surface.The white LED based on the CsPbBr3 fibers exhibits satisfying color gamut performance(128%of National Television System Committee).Due to the short photoluminescence lifetime of CsPbBr3 PQDs,the communication potential is also considered.The CsPbBr3 fibers obtained by centrifugal spinning present a bandwidth of 11.2 MHz,showing promising performance for solid-state light and visible light communication applications.