Dual-single-atoms of Pt-Co boost sulfur redox kinetics for ultrafast Li-S batteries

Applications of lithium-sulfur(Li-S)batteries are still limited by the sluggish conversion kinetics from polysulfide to Li_(2)S.Although various single-atom catalysts are available for improving the conversion kinetics,the sulfur redox kinetics for Li-S batteries is still not ultrafast.Herein,in this work,a catalyst with dual-single-atom Pt-Co embedded in N-doped carbon nanotubes(Pt&Co@NCNT)was proposed by the atomic layer deposition method to suppress the shuttle effect and synergistically improve the interconversion kinetics from polysulfides to Li_(2)S.The X-ray absorption near edge curves indicated the reversible conversion of Li_(2)Sx on the S/Pt&Co@NCNT electrode.Meanwhile,density functional theory demonstrated that the Pt&Co@NCNT promoted the free energy of the phase transition of sulfur species and reduced the oxidative decomposition energy of Li_(2)S.As a result,the batteries assembled with S/Pt&Co@NCNT electrodes exhibited a high capacity retention of 80%at 100 cycles at a current density of 1.3 mA cm^(−2)(S loading:2.5 mg cm^(−2)).More importantly,an excellent rate performance was achieved with a high capacity of 822.1 mAh g^(−1) at a high current density of 12.7 mA cm^(−2).This work opens a new direction to boost the sulfur redox kinetics for ultrafast Li-S batteries.

Projected changes in extreme snowfall events over the Tibetan Plateau based on a set of RCM simulations

Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,RegCM4.The model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 pathways.Four modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall events.RegCM4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of overestimation.For the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern part.All the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the TP.Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP.Notably,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central TP.Significant increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the TP.The projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.

Use of the RegCM System over East Asia： Review and Perspectives

The Abdus Salam International Center for Theoretical Physics （ICTP） RegCM system is one of the most commonly used regional climate models （RCMs） over the East Asia region, In this paper, we present a brief review of the RegCM system and its applications to the East Asia region. The model history and plans for future development are described, Previous and ongoing applications, as well as the advantages and biases found in the model system over the East Asia region, are summarized, The model biases that exist are mainly found in the cold seasons, and are characterized by a warm bias at high latitudes and underestimation of precipitation in the south. These biases are similar to those of most global climate models （GCMs）, Finally, future plans on the application and development of the model, and specifically on those within the context of the Coordinated Regional Climate Downscaling Experiment （CORDEX）, are introduced. This paper is intended to serve as a reference for future users of the RegCM system within the East Asia region.

Projected Changes in Temperature and Precipitation Extremes over China as Measured by 50-yr Return Values and Periods Based on a CMIP5 Ensemble

Future changes in the 50-yr return level for temperature and precipitation extremes over China's Mainland are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The following indices are analyzed： TXx and TNn （the annual maximum and minimum of daily annual maximum consecutive 5-day precipitation） and CDD maximum and minimum surface temperature）, RX5day （the （maximum annual number of consecutive dry days）. After first validating the model performance, future changes in the 50-yr return values and return periods for these indices are investigated along with the inter-model spread. Multi-model median changes show an increase in the 50-yr return values of TXx and a decrease for TNn, more specifically, by the end of the 21st century under RCP8.5, the present day 50-yr return period of warm events is reduced to 1.2 yr, while extreme cold events over the country are projected to essentially disappear. A general increase in RX5day 50-yr return values is found in the future. By the end of the 21st century under RCP8.5, events of the present RX5day 50-yr return period are projected to reduce to 〈 10 yr over most of China. Changes in CDD-50 show a dipole pattern over China, with a decrease in the values and longer return periods in the north, and vice versa in the south. Our study also highlights the need for further improvements in the representation of extreme events in climate models to assess the future risks and engineering design related to large-scale infrastructure in China.

Projection of the Future Changes in Tropical Cyclone Activity Affecting East Asia over the Western North Pacific Based on Multi-RegCM4 Simulations

Future changes in tropical cyclone(TC)activity over the western North Pacific(WNP)under the representative concentration pathway RCP4.5 are investigated based on a set of 21 st century climate change simulations over East Asia with the regional climate model RegCM4 driven by five global models.The RegCM4 reproduces the major features of the observed TC activity over the region in the present-day period of 1986-2005,although with the underestimation of the number of TC genesis and intensity.A low number of TCs making landfall over China is also simulated.By the end of the 21st century(2079-98),the annual mean frequency of TC genesis and occurrence is projected to increase over the WNP by16%and 10%,respectively.The increase in frequency of TC occurrence is in good agreement among the simulations,with the largest increase over the ocean surrounding Taiwan Island and to the south of Japan.The TCs tend to be stronger in the future compared to the present-day period of 1986-2005,with a large increase in the frequency of strong TCs.In addition,more TCs landings are projected over most of the China coast,with an increase of~18%over the whole Chinese territory.

Performance of RegCM4 over Major River Basins in China

A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.

Long-lifespan thin Li anode achieved by dead Li rejuvenation and Li dendrite suppression for all-solid-state lithium batteries

Solid polymer electrolytes(SPEs)are considered to be one of the most promising systems applied in all-solid-state lithium metal batteries(ASSLMBs)on account of their chemical and electrochemical ro bustness,mechanical stability,cost-effective and scalable manufacturing techniques.Lately,significant en deavors have been directed towards mitigating the formation of the Li dendrite in SPE-based ASSLMBs while research on the inactive lithium in the forms of the solid-electrolyte interface has been rarely re ported.Herein,a bi-functional GaI3additive is developed for in-situ generating Li_(3)Ga alloy for suppressing Li dendrite growth,as well as I3-in recovering dead lithium.Relying on the density functional theory(DFT)results,the Li atom prefers to deposit on the Li_(3)Ga surface and then guide uniform Li deposi tion,while the I3species features a relatively lower lowest unoccupied molecular orbital(LUMO)energy level(-2.12 e V),meaning a higher electron affinity,which is beneficial for reviving inactive lithium to counterbalance the loss of lithium.As a result,in comparison to cells employing pure PEGDME-based electrolytes,the Li-Li symmetric cells utilizing GaI3-containing solid-state electrolyte exhibited a cycling life nearly 30 times longer at a current density/capacity of 0.2 mA/cm^(2),0.2 mAh/cm^(2).The full batterie of LFP//1%GaI3-SPE//40μm Li delivered a noteworthy capacity retention of 82%after 1300 cycles at a rate of 1 C.

气候变化情景下中国因高温造成的劳动生产力损失预估

气候变化背景下,高温会影响职业人群的工作效率并造成劳动生产力损失.本研究基于区域气候模式并采用本土化的暴露-反应函数,预估了未来气候变化情景下中国因高温造成的劳动时间损失.研究发现,与基线期的213亿小时高温相关劳动时间损失相比,到21世纪末在RCP2.6、RCP4.5和RCP8.5情景下,损失将分别增加-17.8%、10.8%及121.1%.损失主要集中在华南、华中和华东地区,其中广东与河南将占到全国总损失的四分之一.因为这些区域的温度将更高、人口更密集、户外工作者在总人群中的比例较大.与RCP2.6、RCP4.5和RCP8.5情景相比,若能实现1.5℃温控目标,将分别能够避免11.8%、33.7%和53.9%的劳动时间损失,相当于避免了全中国21世纪中叶的0.1%、0.6%及1.4%的年均GDP损失.本研究显示未来气候变化会给中国造成严重的热相关劳动生产力损失,并强调亟需采取因地制宜的气候减缓及适应策略以保护职业人群健康.本研究对其他与中国相似的发展中国家同样具有重要意义.

In-situ polymerized carbonate induced by Li-Ga alloy as novel artificial interphase on Li metal anode

Li metal is considered an ideal anode material because of its high theoretical capacity and low electrode potential.However,the practical usage of Li metal as an anode is severely limited because of inevitable parasitic side reactions with electrolyte and dendrites formation.At present,single-component artificial solid electrolyte interphase cannot simultaneously meet the multiple functions of promoting ion conduction,guiding lithium ion deposition,inhibiting dendrite growth,and reducing interface side reactions.Therefore,multi-component design on Li metal surface is widely investigated to achieve long-term cycling.Herein,we report a Li_(2)Ga-carbonate polymer interphase layer to solve volume changes,Li dendrites formation and side-reactions.As a result,the Li symmetric cell can be stabilized at 3.0 m A/cm^(2)in carbonate electrolyte with limited volume of 20μL.Coupled with 13.6 mg/cm^(2)(loading of 2 mAh/cm^(2))LiFePO_(4)cathode,discharge capacity retains at 90%for over 150 cycles under limited electrolyte conditions.With such an alloy-polymer interphase layer,higher energy density Li metal batteries become prominent in the near future.