Unraveling the heterogeneity of solid electrolyte interphase kinetically affecting lithium electrodeposition on lithium metal anode

The stability and uniformity of solid electrolyte interphase(SEI)are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes(LMA).However,understanding the interplay of SEI heterogeneity and Li electrodeposition is limited by the coupling of complex electrochemistry and mechanics processes.Herein,the correlation between the SEI failure behavior and Li deposition morphology is investigated through a quantitative electrochemical-mechanical model.The local deformation and stress of SEI during Li electrodeposition identify that the heterogeneous interface between different components first fails.Compared with the well-known mechanical strength,component uniformity plays the most important role in the initial SEI failure and uneven Li deposition,and a relative component uniformity(p>0.01)represents a proper balance to ensure the stability of the naturally heterogeneous SEI.Furthermore,the component regulation of SEI via the designed electrolyte experimentally demonstrates that improving component uniformity benefits SEI stability and the uniform Li electrodeposition for LMA,thereby increasing the capacity by~20%after 300 cycles.These fundamental understandings and proposed strategy can be not only used to guide the SEI optimization via the electrolyte regulation,but also extended to the rational designs of artificial SEI for high-performance LMA.

A spatial-explicit dynamic vegetation model that couples carbon,water,and nitrogen processes for arid and semiarid ecosystems

Arid and semiarid ecosystems, or dryland, are important to global biogeochemical cycles. Dryland＇s community structure and vegetation dynamics as well as biogeochemical cycles are sensitive to changes in climate and atmospheric composition. Vegetation dynamic models has been applied in global change studies, but the com- plex interactions among the carbon （C）, water, and nitrogen （N） cycles have not been adequately addressed in the current models. In this study, a process-based vegetation dynamic model was developed to study the responses of dryland ecosystems to environmental changes, emphasizing on the interactions among the C, water, and N proc- esses. To address the interactions between the C and water processes, it not only considers the effects of annual precipitation on vegetation distribution and soil moisture on organic matter （SOM） decomposition, but also explicitly models root competition for water and the water compensation processes. To address the interactions between C and N processes, it models the soil inorganic mater processes, such as N mineralization/immobilization, denitrifica- tion/nitrification, and N leaching, as well as the root competition for soil N. The model was parameterized for major plant functional types and evaluated against field observations.

Modeling the contribution of abiotic exchange to CO_2 flux in alkaline soils of arid areas

Recent studies on alkaline soils of arid areas suggest a possible contribution of abiotic exchange to soil CO2 flux(Fc).However,both the overall contribution of abiotic CO2 exchange and its drivers remain unknown.Here we analyzed the environmental variables suggested as possible drivers by previous studies and constructed a function of these variables to model the contribution of abiotic exchange to Fc in alkaline soils of arid areas.An automated flux system was employed to measure Fc in the Manas River Basin of Xinjiang Uygur autonomous region,China.Soil pH,soil temperature at 0–5 cm(Ts),soil volumetric water content at 0–5 cm(θs)and air temperature at10 cm above the soil surface(Tas)were simultaneously analyzed.Results highlight reduced sensitivity of Fc to Ts and good prediction of Fc by the model Fc=R10Q10(Tas–10)/10+r7q7(pH–7)+λTas+μθs+e which represents Fc as a sum of biotic and abiotic components.This presents an approximate method to quantify the contribution of soil abiotic CO2 exchange to Fc in alkaline soils of arid areas.

基于联合仿真的短纤维增强聚合物共混挤出-注塑成形全流程模拟

短纤维增强聚合物广泛应用于汽车、电子、机械等领域,共混挤出和注塑成形是其最常见的制备和成形工艺。现有共混挤出与注塑成形的模拟仿真存在材料和工艺信息孤立、产品优化协同困难的问题,难以满足聚合物产品高端化与定制化的发展需求。文中提出了一种短纤维增强聚合物共混挤出-注塑成形过程的联合仿真方法,建立共混挤出过程全区域流场计算模型,基于流场模拟实现纤维断裂和纤维长度分布模拟,在此基础上,建立考虑纤维含量的流变与压力-比容-温度(PVT)模型计算材料等效热力学参数,通过模流-结构性能求解注塑拉伸试样的纤维取向与弹性模量分布,实现共混挤出-注塑成形全流程模拟。纤维质量分数为20%,30%和40%的玻纤增强尼龙6注塑拉伸试样弹性模量实验与模拟结果相对误差分别为9.94%,8.32%和3.72%,验证了联合仿真的准确性。

钛合金-芳纶纤维复合材料单搭接接头的失效形式

采用钛合金与芳纶纤维复合材料制备同质与异质材料单搭接胶接接头。利用数字图像相关技术、万能试验机、光学显微镜等手段,对拉伸载荷下的接头应变、极限载荷与破坏模式进行表征,分析不同搭接材料接头应变场及胶接性能,研究了钛合金-芳纶纤维复合材料接头失效形式。结果表明,在拉伸载荷下,钛合金-芳纶纤维复合材料接头复合材料应变远大于钛合金应变,搭接区域外部应变大于搭接区域内应变;接头偏移及被胶接件变形高于钛合金或芳纶纤维复合材料同质接头,承载能力较低;搭接区域复合材料端头剥离及剪切应力集中,是接头的薄弱部位,易出现渐进失效;破坏模式主要为复合材料层间破坏与钛合金-胶层界面破坏,芳纶纤维丝束承受剥离或剪切力断裂。

Spherical cationic polymer networks with porphyrin photosensitizer for sustainable and efficient photocatalysis

The continuous and sustainable photo-activity on micro-or nano-carriers has always been a key stepping stone in the industrialization of photo-catalysis,photo-synthesis,and photo-degradation.Herein,we report a new series of positively charged hollow microspheres carrying porphyrin moieties.Such hollow spheres are formed through crosslinking of well-ordered porous thin laminates,initiated by co-assembly of regular monomers and those decorated with porphyrin moieties.On the surface of an individual sphere,densely distributed positive sites attract anionic reactants.The superficial porphyrin decomposes the accumulated reactants under 1 Sun.After degradation and release of products,the photoactive sites are thereby renewed.We demonstrate that polymer network(1:10)exhibited superior sustainable photocatalytic performance with complete degradation of methyl orange(MO)in 40 min with no observable performance deterioration after six cycles.The established close loop of adsorption-reaction-release cycle makes possible many efficient and continuous photo-catalytic processes.