Rationally designing electrolyte additives for highly improving cyclability of LiNi_(0.5)Mn_(1.5)O_(4)/Graphite cells

High voltage is necessary for high energy lithium-ion batteries but difficult to achieve because of the highly deteriorated cyclability of the batteries.A novel strategy is developed to extend cyclability of a high voltage lithium-ion battery,LiNi_(0.5)Mn_(1.5)O_(4)/Graphite(LNMO/Graphite)cell,which emphasizes a rational design of an electrolyte additive that can effectively construct protective interphases on anode and cathode and highly eliminate the effect of hydrogen fluoride(HF).5-Trifluoromethylpyridine-trime thyl lithium borate(LTFMP-TMB),is synthesized,featuring with multi-functionalities.Its anion TFMPTMB-tends to be enriched on cathode and can be preferentially oxidized yielding TMB and radical TFMP-.Both TMB and radical TFMP can combine HF and thus eliminate the detrimental effect of HF on cathode,while the TMB dragged on cathode thus takes a preferential oxidation and constructs a protective cathode interphase.On the other hand,LTFMP-TMB is preferentially reduced on anode and constructs a protective anode interphase.Consequently,a small amount of LTFMP-TMB(0.2%)in 1.0 M LiPF6in EC/DEC/EMC(3/2/5,wt%)results in a highly improved cyclability of LNMO/Graphite cell,with the capacity retention enhanced from 52%to 80%after 150 cycles at 0.5 C between 3.5 and 4.8 V.The as-developed strategy provides a model of designing electrolyte additives for improving cyclability of high voltage batteries.

Toward a fundamental understanding of the heterogeneous multiphysics behaviors of silicon monoxide/graphite composite anodes

Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion batteries.The major bottleneck for SiO/Gr composite anode is the poor cyclability arising from the stress/strain behaviors due to the mismatch between two heterogenous materials during the lithiation/delithiation process.To date,a meticulous and quantitative understanding of the highly nonlinear coupling behaviors of such materials is still lacking.Herein,an electro–chemo–mechanics-coupled detailed model containing particle geometries is established.The underlying mechanism of the regulation between SiO and Gr components during electrochemical cycling is quantitatively revealed.We discover that increasing the SiO weight percentage(wt%)reduces the utilization efficiency of the active materials at the same 1C rate charging and enhances the hindering effects of stress-driven flux on diffusion.In addition,the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles.This study provides new insights into the fundamental interactions between SiO and Gr materials and advances the investigation methodology for the design and evaluation of next-generation high-energydensity batteries.

Highly improved cyclic stability of Ni-rich/Li batteries with succinic anhydride as electrolyte additive and underlying mechanism

Lithium-metal battery based on Ni-rich cathode provides high energy density but presents poor cyclic stability due to the unstable electrode/electrolyte interfaces on both cathode and anode.In this work,we report a new strategy to address this issue.It is found that the cyclic stability of Ni-rich/Li battery can be significantly improved by using succinic anhydride(SA) as an electrolyte additive.Specifically,the capacity retention of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)/Li cell is improved from 14% to 83% after 200cycles at 1 C between 3.0 and 4.35 V by applying 5% SA.The underlying mechanism of SA contribution is understood by comparing the effects of malic anhydride(MA) and citraconic anhydride(CA), both of which share a similar molecular structure to SA but show different effects.On anode side,SA can but MA and CA cannot form a protective solid electrolyte interphase(SEI) on Li anode.On cathode side,three anhydrides can suppress the formation of hydrogen fluoride from electrolyte oxidation decomposition,but SA behaves best.Typically,MA shows adverse effects on the interface stability of Li anode and NCM811 cathode,which originates from its high acidity.Though the acidity of MA can be mitigated by substituting a methyl for one H atom at its C=C bond,the substituent CA cannot compete with SA in cyclic stability improvement of the cell,because the SEI resulting from CA is not as robust as that from SA,which is related to the binding energy of the SEI components.This understanding reveals the importance of the electrolyte acidity on the Ni-rich cathode and the robustness of the SEI on Li anode,which is helpful for rationally designing new electrolyte additives to further improve the cyclic stability of high-energydensity Ni-rich/Li batteries.

An ignored key link in greenhouse effect:Soil and soil CO_(2) slow heat loss

The ever-increasing atmospheric CO_(2) concentration is a key driver of modern global warming.However,the low heat capacity of atmosphere and strong convection processes in the troposphere both limit heat retention.Given the higher heat capacity and CO_(2) concentration in soil compared to the atmosphere,the direct contributions of soil to the greenhouse effect may be significant.By experimentally manipulating CO_(2) concentrations both in the soil and the atmosphere,we demonstrated that the soil-retained heat and the slower soil heat transmission decrease the amount of heat energy leaking from the earth.Furthermore,the soil air temperature was affected by soil CO_(2) concentration,with the highest value recorded at 7500 ppm CO_(2).This study indicates that soil and soil CO_(2),together with atmospheric CO_(2),play a crucial role in the greenhouse effect.The spatial and temporal heterogeneity of soils and soil CO_(2) should be further investigated,given their potentially significant influence on global climate change.

新疆某三甲医院早发糖尿病患者中青少年起病的成人型糖尿病的基因筛查分析

本研究通过对新疆地区某三甲医院早发糖尿病患者进行青少年起病的成人型糖尿病(MODY)相关基因检测,了解其检出率。收集2015年1月至2020年12月新疆维吾尔自治区人民医院内分泌科收治的334例早发糖尿病患者的临床资料,并对其中122例进行基因检测,根据基因检测结果,比较MODY患者与非MODY患者的临床表型的差异。结果显示,5例(4.1%)患者可明确诊断为MODY,其中MODY32例,MODY51例,MODY81例,MODY101例。与非MODY患者相比,MODY患者发病年龄更早[分别为(19.60±10.53)和(30.48±10.72)岁,P=0.28],总胆固醇水平更高[分别为(6.30±1.25)和(4.67±1.62)mmol/L,P=0.49],这可能与不同MODY类型特点相关。综上,本地区MODY检出率为4.1%,基因检测有助于MODY精准分型及个体化治疗。

Identification and selection of resistance to Bemisia tabaci among 550 cotton genotypes in the field and greenhouse experiments

Plants have developed sophisticated systems to cope with herbivore challenge, including morphological barriers and secondary metabolites to reduce damage. In this study, 550 Gossypium genotypes were evaluated for whitefly(Bemisia tabaci) resistance in five experiments including two in the field and three in the greenhouse, with23 resistant and 19 susceptible genotypes selected.Whitefly-resistance index determination showed that a leaf having a high density of hairs had resistance to whitfly egg/nymph production. Longer leaf hairs were also important for resistance. This study revealed that okra shaped leaves reduced adult whitefly oviposition preference, while glabrous leaves and high hair density helped not only in the reduction of the adults but also decreased oviposition preference. Gossypol was also observed to be involved in the reduction of adult whitefly development and/or survival.