Tailored deep-eutectic solvent method to enable 3D porous iron fluoride bricks for conversion-type lithium batteries

Conversion-type fluoride cathode can provide considerable energy density for Li batteries,however its scalable and facile synthesis strategies are still lacking.Here,a novel Fe-based deep eutectic solvent composed of nitrite and methylsulfonylmethane is proposed as both the reaction medium and precursor to synthesize O-doped FeF3porous bricks.This method is cheaper,safe,mildly operable,environmentally friendly and recyclable for non-fluorinated metal cations.The homogenization of charge and mass transport in cathode network effectively mitigates the volume extrusion and electrode coarsening even for the micro-sized monolithic particles.The Co-solvation modulated fluoride cathode delivers high reversible capacity in a wide temperature range(486 and 235 mA h g^(-1)at 25℃ and-20℃ respectively),excellent rate performance(312 mA h g^(-1)at 1000 mA g^(-1)),corresponding to an energy density as high as672.1 W h kg^(-1)under a power density of 2154.3 W kg^(-1).The successful operation of fluoride pouchcell with a capacity exceeding 450 mA h g^(-1)(even under thin Li foil and lean electrolyte conditions) indicates its potentiality of commercial application.

Nanodiamonds decorated yolk-shell ZnFe_(2)O_(4) sphere as magnetically separable and recyclable composite for boosting antibiotic degradation performance

Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have become major bottlenecks for marvelous photocatalytic performance of photocatalysts.Herein, to address these issue, Nanodiamonds/yolk-shell ZnFe_(2)O_(4) spheres(NDs/ZFO) nanocomposites were successfully constructed via a facile two-step of solvothermal and calcination methods. The synthesized optimal NDs/ZFO-10 nanocomposite exhibits superior photocatalytic degradation activity of antibiotic under visible light, approximately 85% of the total tetracycline(TC) is degraded, and this photocatalyst shows durable cycling stability. This stems from two aspects of refinement: improvement of light absorption capacity and photo-induced charges migration and separation. In addition, the NDs/ZFO composite photocatalyst features excellent magnetic recovery capability, facilitating the recovery of photocatalyst in industry. This study opens a new chapter in the combination of NDs with magnetic materials, and deepens the understanding of the application of NDs modified composite photocatalysts.

Assimilation of Feng-Yun-3B Satellite Microwave Humidity Sounder Data over Land

The ECMWF has been assimilating Feng-Yun-3B （FY-3B） satellite microwave humidity sounder （MWHS） data over ocean in an operational forecasting system since 24 September 2014, It is more difficult, however, to assimilate microwave observations over land and sea ice than over the open ocean due to higher uncertainties in land surface temperature, surface emissivity and less effective cloud screening. We compare approaches in which the emissivity is retrieved dynamically from MWHS channel l [150 GHz （vertical polarization）] with the use of an evolving emissivity atlas from 89 GHz observations from the MWHS onboard NOAA and EUMETSAT satellites. The assimilation of the additional data over land improves the fit of short-range forecasts to other observations, notably ATMS （Advanced Technology Microwave Sounder） humidity channels, and the forecast impacts are mainly neutral to slightly positive over the first five days. The forecast impacts are better in boreal summer and the Southern Hemisphere. These results suggest that the techniques tested allow for effective assimilation of MWHS/FY-3B data over land.

Growing Operational Use of FY-3 Data in the ECMWF System

This paper reviews the data quality and impact of observations from the FY-3 satellite series used operationally in the ECMWF system. This includes data from the passive microwave radiometers MWHS-1, MWHS-2 and MWRI, as well as observations from the radio occultation receiver GNOS. Evaluations against background equivalents show that the quality of the observations is broadly comparable to that of similar instruments on other polar-orbiting satellites, even though biases for the passive microwave observations can be somewhat larger and more complex for some channels. An observing system experiment shows that the FY-3 instruments jointly contribute significantly to the forecast skill in the ECMWF system. Positive impact of up to 2% is seen for most variables out to the day-2 forecasts over hemispheric scales, with significant benefits for total column water vapor or for temperature and wind in the stratosphere out to day 4.

Evaluation of All-Sky Assimilation of FY-3C/MWHS-2 on Mei-yu Precipitation Forecasts over the Yangtze-Huaihe River Basin

All-sky (i.e., clear, cloudy, and precipitating conditions) assimilation of microwave observations shows potentially positive impacts on the improvement of the forecasts of cloud-associated weather processes. In this study, a typical mei-yu heavy precipitation event that occurred in 2017 was investigated, and the Weather Research and Forecasting data assimilation (WRFDA) as well as its 3D-Var assimilation scheme (excluding cloud and precipitation control variables) were applied to assimilate the Fengyun-3C (FY-3C) Microwave Humidity Sounder-2 (MWHS-2) observations under clear- sky (excluding the observations that are strongly affected by ice clouds and precipitation) and all-sky conditions. Three experiments including a control experiment without assimilating any observations, clear-sky, and all-sky experiments with only FY-3C/MWHS-2 observations assimilated were carried out. The results show that the all-sky assimilation approach that provides more cloud and precipitation information and increased more than 10% of the satellite data usage than the clear-sky experiment. Meanwhile, as compared with the control experiment, the all-sky assimilation reduced nearly 0.5% of the root mean square errors in the humidity fields, leading to more accurate forecast performances regarding the distribution and intensity of heavy rainfall;but it exhibited a neutral to negative impacts on the wind and temperature. Although the system used to conduct all-sky assimilation is only able to adjust control variables for moisture-, wind-, and temperature- related variables in the presence of cloud and does not benefit directly from cloud or precipitation information, the positive effects on heavy rainfall forecasts achieved in this study indicate a potential future benefit regarding disaster prevention and mitigation.

Incorporating topographic factors in nonlinear mixed-effects models for aboveground biomass of natural Simao pine in Yunnan,China

A total of 128 Simao pine trees （Pinus kesiya var. langbianensis） from three regions of Pu＇er City, Yunnan Province, People＇s Republic of China, were destructively sampled to obtain tree aboveground biomass （AGB）. Tree variables such as diameter at breast height and total height, and topographical factors such as altitude, aspect of slope, and degree of slope were recorded. We considered the region and site quality classes as the ran- dom-effects, and the topographic variables as the fixed- effects. We fitted a total of eight models as follows： least- squares nonlinear models （BM）, least-squares nonlinear models with the topographic factors （BMT）, nonlinear mixed-effects models with region as single random-effects （NLME-RE）, nonlinear mixed-effects models with site as single random-effects （NLME-SE）, nonlinear mixed-ef- fects models with the two-level nested region and site random-effects （TLNLME）, NLME-RE with the fixed-ef- fects of topographic factors （NLMET-RE）, NLME-SE with the fixed-effects of topographic factors （NLMET-SE）, and TLNLME with the fixed-effects of topographic factors （TLNLMET）. The eight models were compared by modelfitting and prediction statistics. The results showed： model fitting was improved by considering random-effects of region or site, or both. The models with the fixed-effects of topographic factors had better model fitting. According to AIC and BIC, the model fitting was ranked as TLNLME 〉 NLMET-RE 〉 NLME-RE.〉 NLMET-SE 〉 TLNLMET 〉 NLME-SE 〉 BMT 〉 BM. The differences among these models for model prediction were small. The model pre- diction was ranked as TLNLME 〉 NLME-RE 〉 NLME- SE 〉 NLMET-RE 〉 NLMET-SE 〉 TLNLMET 〉 BMT 〉 BM. However, all eight models had relatively high prediction precision （〉90 %）. Thus, the best model should be chosen based on the available data when using the model to predict individual tree AGB.

Monitoring Mongolia Gobi dust transport using OMI data

The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI （Ozone Monitoring Instrument Aerosol Index） data during 2005-007. The results show that there is a high correla- tion of At （the correlation coefficients are as high as 0.83 in March, 0.62 in April and 054 in May） between the Mongolia Gobi Desert and the west coast region of the United States （40°-50°N, 120°- 130°W）, indicating a strong source-receptor area relationship. Through calculating the lag correlation coefficient of the dust propagation time, we determined that the dust propagation lime fi＇om the Mongolia Gobi Desert to the west coast of the United States is about 6-7 days at the 99% confidence level.

The recirculation flow after different cross-section shaped high-rise buildings with applications to ventilation assessment and drag parameterization

The building cross-section shape significantly affects the flow characteristics around buildings,especially the recirculation region behind the high-rise building.Eight generic building shapes including square,triangle,octagon,T-shaped,cross-shaped,#-shaped,H-shaped and L-shaped are examined to elucidate their effects on the flow patterns,recirculation length L and areas A using computational fluid dynamics(CFD)simulations with Reynolds-averaged Navier-Stokes(RANS)approach.The sizes and positions of the vortexes behind the buildings are found to be substantially affected by the building shapes and subsequently changing the recirculation flows.The recirculation length L is in the range of 1.6b-2.6b with an average of 2b.The maximum L is found for L-shaped building(2.6b)while the shortest behind octagon building(1.6b).The vertical recirculation area Av is in the range of 1.5b^(2)-3.2b^(2)and horizontal area Ah in 0.9b^(2)-2.2b^(2).The L,Av and Ah generally increase with increasing approaching frontal area when the wind direction changes but subject to the dent structures of the#-shaped and cross-shaped buildings.The area-averaged wind velocity ratio(AVR),which is proposed to assess the ventilation performance,is in the range of 0.05 and 0.14,which is around a three-fold difference among the different building shapes.The drag coefficient parameterized by Ah varies significantly,suggesting that previous models without accounting for building shape effect could result in large uncertainty in the drag predictions.These findings provide important reference for improving pedestrian wind environment and shed some light on refining the urban canopy parameterization by considering the building shape effect.

Polymer electrolytes reinforced by 2D fluorinated filler for all-solidstate Li-Fe-F conversion-type lithium metal batteries

The polyethylene oxide(PEO)based solid-state batteries are considered as promising candidates for the next-generation Li metal batteries with high energy density and safety.However,the low Li-ion conductivity and high-voltage endurability hinder the further applications of PEO-based electrolytes.To overcome these issues,herein two-dimensional(2D)CeF_(3)nanoplates with maximally exposed[001]crystal faces are introduced into the PEO matrix to expand the electrochemical window and improve Liion conduction and transport.The optimized crystal shape and crystal face anisotropy of CeF_(3)nanoplate filler reduce the crystallinity of composite solid polymer electrolyte(CSPE)via its Lewis acid-base interaction with ether oxygen of PEO.The Liaffinity[100]and Li-repellent[001]crystal faces of CeF_(3)nanoplates synergistically realize the dissociation of lithium bis(trifluoromethanesulfonyl)imide(LiTFSI),fast Li-adsorption/desorption,and Li+migration.The optimized CSPE-0.1CeF_(3)membrane enables the achievement of Li metal batteries with high endurability and stability,from the kinetically favorable Li/Li symmetric cells with long-term cycling over 8000 h.The highly reversible Li/LiFePO_(4) cells exhibit a capacity retention of 109.2 mAh·g^(−1)after 1000 cycles at 1 C,corresponding to a low capacity fading rate of 0.026%per cycle.The conversion-type allsolid-state Li/CSPE-0.1CeF_(3)/FeF_(3)cells show a high reversible capacity of 201.9 mAh·g^(−1)after long-term 600 cycles and of 231.1 mAh·g^(−1)at an ultra-high rate of 5 C.

不同叶色矢竹叶绿体结构和光系统特性差异

以矢竹(Pseudosasa japonica)、花叶矢竹(P.japonica f.akebonosuji)和曙筋矢竹(P.japonica f.akebono)为研究对象,借助叶绿体超微结构和荧光动力学曲线的变化揭示不同叶色矢竹的光系统活性及光合特性差异。结果表明:3个竹种的光合色素含量差异明显,除花叶矢竹条纹叶白色部分叶绿体内无完整类囊体片层结构外,花叶矢竹绿条纹和曙筋矢竹的基粒数明显少于矢竹,叶绿体发育成熟度不一致;OJIP曲线及参数表明,花叶矢竹条纹绿叶和曙筋矢竹光系统II(PSII)反应中心开放降低程度低于矢竹,捕获能量用于电子传递的份额变小,PSII活性变弱;而曙筋矢竹叶片P700至初级电子受体(QA)的电子传递链氧化还原平衡偏向于还原侧,推测其光系统I(PSI)反应中心P700至PSII QA电子传递链受损。因此,PSII活性变化导致叶绿体发育不成熟,可能是引起矢竹类叶色差异的直接原因。

Electrochemically driven conversion reaction in fluoride electrodes for energy storage devices

Exploring electrochemically driven conversion reactions for the development of novel energy storage materials is an important topic as they can deliver higher energy densities than current Li-ion battery electrodes.Conversion-type fluorides promise particularly high energy densities by involving the light and small fluoride anion,and bond breaking can occur at relatively low Li activity(i.e.,high cell voltage).Cells based on such electrodes may become competitors to other envisaged alternatives such as Lisulfur or Li-air systems with their many unsolved thermodynamic and kinetic problems.Relevant conversion reactions are typically multiphase redox reactions characterized by nucleation and growth processes along with pronounced interfacial and mass transport phenomena.Hence significant overpotentials and nonequilibrium reaction pathways are involved.In this review,we summarize recent findings in terms of phase evolution phenomena and mechanistic features of(oxy)fluorides at different redox stages during the conversion process,enabled by advanced characterization technologies and simulation methods.It can be concluded that well-designed nanostructured architectures are helpful in mitigating kinetic problems such as the usually pronounced voltage hysteresis.In this context,doping and open-framework strategies are useful.By these tools,simple materials that are unable to allow for substantial Li nonstoichiometry(e.g.,by Li-insertable channels)may be turned into electroactive materials.

Unlocking solid-state conversion batteries reinforced by hierarchical microsphere stacked polymer electrolyte

Pursuing all-solid-state lithium metal batteries with dual upgrading of safety and energy density is of great significance. However, searching compatible solid electrolyte and reversible conversion cathode is still a big challenge. The phase transformation at cathode and Li deformation at anode would usually deactivate the electrode-electrolyte interfaces. Herein, we propose an all-solid-state Li-FeF_(3) conversion battery reinforced by hierarchical microsphere stacked polymer electrolyte for the first time. This gC_(3)N_(4) stuffed polyethylene oxide(PEO)-based electrolyte is lightweight due to the absence of metal element doping, and it enables the spatial confinement and dissolution suppression of conversion products at soft cathode-polymer interface, as well as Li dendrite inhibition at filler-reinforced anode-polymer interface. Two-dimensional(2 D)-nanosheet-built porous g-C_(3)N_(4) as three-dimensional(3 D) textured filler can strongly cross-link with PEO matrix and Li TFSI(TFSI: bistrifluoromethanesulfonimide) anion, leading to a more conductive and salt-dissociated interface and therefore improved conductivity(2.5×10^(-4) S/cm at 60℃) and Li+transference number(0.69). The compact stacking of highly regular robust microspheres in polymer electrolyte enables a successful stabilization and smoothening of Li metal with ultra-long plating/striping cycling for at least 10,000 h. The corresponding Li/LiFePO_(4) solid cells can endure an extremely high rate of 12 C. All-solid-state Li/FeF_(3) cells show highly stabilized capacity as high as 300 m Ah/g even after 200 cycles and of 200 m Ah/g at extremely high rate of 5 C, as well as ultra-long cycling for at least 1200 cycles at 1 C. High pseudocapacitance contribution(>55%) and diffusion coefficient(as high as10^(-12) cm^(2)/s) are responsible for this high-rate fluoride conversion. This result provides a promising solution to conversion-type Li metal batteries of high energy and safety beyond Li-S batteries, which are difficult to realize true "all-solid-state" due to the indispensable step of polysulfide solid-liquid conversion.