优化Li||NCM811电池电解液溶剂化和电极电解液界面的阴离子受体添加剂策略

锂金属电池的循环稳定性和倍率能力受制于多个因素,如阳极/阴极电解液界面的品质和电解液溶剂化特性。在该工作中,我们提出了阴离子受体电解液添加剂策略,通过六氟苯添加剂对Li^(+)溶剂化结构进行调控,实现了PF_(6)^(-)的稳定性并提高了电解液的导电性,优化了阳极/阴极电解液界面中间相的组分/结构特征,有效抑制了锂枝晶的生长和提升了阴极表面的Li^(+)传输,Li||Li对称电池在1m A·cm^(-2)的电流密度下实现超过400h的稳定循环,并且Li||NCM811电池在200m A·g^(-1)的电流密度下经过100次循环后的容量保持率达到75%。

Electrospun CoSe@N-doped carbon nanofibers with highly capacitive Li storage

One-dimensional nano-structured materials have attracted attention due to its unique properties afforded such as the across-linked structures and large aspect ratios.In this work,one-dimensional CoSe@N-doped carbon nanofibers(CoSe@NCNFs)are successfully by combining the techniques of electrospinning and annealing.Selenium powder are directly dispersed in the polyacrylonitrile/N,N-Dimethylformamide(DMF)solution containing cobalt salt to form the product.The performance of these materials was investigated in Li-ion batteries after the annealing at different temperatures.The Co Se@NC nanofibers annealed at 550℃(CoSe@NC-550)and displayed excellent storage properties,affording a high capacity of 796 m Ah·g-1at a current density of 1 A·g^-1 for 100 cycles.Moreover,it is confirmed that the pseudocapacitive contribution of CoSe@NC-550 is up to 72.8%at the scan rate of 1 mV/s through the cyclic voltammetry analysis.

Structurally tunable characteristics of ionic liquids for optimizing lithium plating/stripping via electrolyte engineering

Electrolyte chemistry offers the opportunity to regulate the solid electrolyte interphase(SEI) and Li^(+)solvation,which is considered to be crucial to the growth of lithium crystals for safe lithium metal batteries(LMBs).Structurally tunable characteristics of ionic liquids(ILs) from anion type,cationic substituent chain length and cationic substituents,will contribute this field.Here,we explore the influence mechanism of imidazole-based ILs as electrolyte additives on Li+solvation and the formation of SEI.ILs can participate into the formation of efficient SEI,together with cathode electrolyte interphase(CEI).Moreover,ILs can also regulate the sheath structure of Li^(+)solvation,to fasten the kinetics of Li.Furthermore,the imidazole-based cations with long alkyl chain can form an electrostatic shield around newly formed Li nucleus,and suppress further Li plating at this site.Under the optimized condition,the 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([OMIm]TFSI) additive shows the best ability to enhance the electrochemical performance,endowing the Li||Li symmetric cell with a stable life(over800 h) at 0.5 mA cm^(-2) and the Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2)(NMC622) full cell with a high capacity of 141.7 mAh g^(-1) after 200 cycles at 0.5 C.

Diethyl phenylphosphonite contributing to solid electrolyte interphase and cathode electrolyte interphase for lithium metal batteries

Lithium metal batteries have obtained increasing interest due to their high specific capacity.Nonetheless,the growth of lithium dendrites brings safety risks to batteries and further deteriorates the performance.Herein,we explore diethyl phenylphosphonite(DEPP) as the electrolyte additive to alleviate this problem.DEPP can be preferentially decomposed than carbonate solvents to form the stable interface between electrolyte and lithium anode for inhibiting the dendrite growth.As expected,the symmetrical LiIILi cells could achieve a stable cycling performance with 200 h at 1 mA cm^(-2).Moreover,DEPP can be preferentially oxidized on the surface of lithium cobalt oxides(LiCoO_(2)) to form a dense cathode electrolyte interphase(CEI) film for suppressing the continuous oxidative decomposition of the electrolyte and eliminating the adverse effects of HF on the battery.This endows LiCoO_(2) IILi full battery with the enhanced cycling and rate performance.

Motion-Blurred Image Restoration Based on Joint Invertibility of PSFs

To implement restoration in a single motion blurred image,the PSF(Point Spread Function)is difficult to estimate and the image deconvolution is ill-posed as a result that a good recovery effect cannot be obtained.Considering that several different PSFs can get joint invertibility to make restoration wellposed,we proposed a motion-blurred image restoration method based on joint invertibility of PSFs by means of computational photography.Firstly,we designed a set of observation device which composed by multiple cameras with the same parameters to shoot the moving target in the same field of view continuously to obtain the target images with the same background.The target images have the same brightness,but different exposure time and different motion blur length.It is easy to estimate the blur PSFs of the target images make use of the sequence frames obtained by one camera.According to the motion blur superposition feature of the target and its background,the complete blurred target images can be extracted from the observed images respectively.Finally,for the same target images with different PSFs,the iterative restoration is solved by joint solution of multiple images in spatial domain.The experiments showed that the moving target observation device designed by this method had lower requirements on hardware conditions,and the observed images are more convenient to use joint-PSF solution for image restoration,and the restoration results maintained details well and had lower signal noise ratio(SNR).

Thermospheric density responses to Martian dust storm in autumn based on MAVEN data

The unique seasonal surface dust storms on Mars have a significant impact on the Martian atmosphere.However,due to the lack of observations,semi-empirical models are difficult to simulate the density changes in the thermosphere with the existence of dust storms in detail.Data from multiple Mars probes now offer new opportunities to study the detailed response of Martian dust storms to the upper atmosphere.In this paper,we use MAVEN accelerometer and mass spectrometer to study the variations of the Martian thermosphere density in autumn between MY32 and MY34(The corresponding Earth dates:February 11,2015 to February 28,2019),and use the seasonal model with dust storm index to fit the annual data of the above three Martian years.The results show that the thermosphere density has a clear response to the surface dust storm activity.Furthermore,the spatial distribution of measured data in autumn(northern hemisphere)is compared with the atmospheric density distribution simulated by the general circulation model(GCM)under specific initial conditions.The model simulation results agree well with the thermospheric density distribution characteristics of each Martian year under the initial strong dust storm conditions.It proves the important role of global dust storm in changing the structure of the Martian thermospheric atmosphere.

Research progress in failure mechanisms and electrolyte modification of high-voltage nickel-rich layered oxide-based lithium metal batteries

High-voltage nickel(Ni)-rich layered oxide-based lithium metal batteries(LMBs)exhibit a great potential in advanced batteries due to the ultra-high energy density.However,it is still necessary to deal with the challenges in poor cyclic and thermal stability before realizing practical application where cycling life is considered.Among many improved strategies,mechanical and chemical stability for the electrode electrolyte interface plays a key role in addressing these challenges.Therefore,extensive effort has been made to address the challenges of electrode-electrolyte interface.In this progress,the failure mechanism of Ni-rich cathode,lithium metal anode and electrolytes are reviewed,and the latest breakthrough in stabilizing electrode-electrolyte interface is also summarized.Finally,the challenges and future research directions of Ni-rich LMBs are put forward.

通过电解液添加剂构筑富含LiF/Li_(2)CO_(3)异质结构的电极-电解质界面以实现4.5V锂金属电池的稳定循环

高压Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)电池的循环性能取决于电极和电解质之间的界面稳定性.然而,在高电压下实现它们是具有挑战性的本文以五氟苯乙烯(PFBE)为添加剂,通过电解液工程稳定了4.5VLi||NCM811电池.添加剂PFBE有助于在NCM811阴极和锂金属阳极表面形成高导锂和机械坚固的富含无机组分LiF/Li_(2)CO_(3)的异质结构界面.这种电极-电解质界面(EEIs)明显缓解了富镍层状阴极中不可逆相变、应力积累引起的微裂纹和过渡金属溶解.同时,有效地控制了锂金属阳极表面锂枝晶的生长,结果表明,4.5VLi||NCM811电池在0.5C(100mAg)下循环600次后,容量保持率为61.27%.此外,在含有这种电解质添加剂中循环的Li||NCM811软包电池可以实现稳定的、高达~485Whkg^(-1)的能量密度.

Weakly solvated electrolytes conducive to uniform lithium deposition

Rechargeable lithium metal batteries(LMBs)meet the demands of high-energy applications in electric vehicles and truck transportation[1-4].Yet,the low coulombic efficiency(CE)hinders the widespread application of Li anode,which is closely related to the electrolytes[5-7].The CE of traditional electrolytes for Li anodes is closely related to the speciation of the plated Li during cycling,where fluorinated solvents with weakly solvated Li+usually exhibit larger Li deposition particles with higher CE[8,9].But the relationship between the morphological difference and CE in different electrolytes is less studied[10,11].There are three relationships between the deposition kinetics of interface Li and the cycling of the battery,no correlation,positive correlation[12,13],and negative correlation[14,15]have been reported on active Li anodes,which neglects the reactivity of Li metal in kinetics.Solid electrolyte interphase(SEl)was formed by the electrolytes reacting with Li,and Li deposition can occur on the Li/SEl interface or the fresh Li/electrolyte interface[16,17].Each pathway has different deposition kinetics.Therefore,in order to understand the relationship between electrolyte kinetics and lithium deposition morphology,it is important to solve the kinetics of the two ways in the electrolyte.

电解液添加剂多因子设计原则:以金属锂电池电解液添加剂全氟烷基磺酸钾盐为例

随着便携式电子设备、电动汽车、智能电网等领域的快速发展,市场对于高能量密度储能器件的需要日益增长.以石墨为负极的传统锂离子电池能量密度有限,尤其是与电动汽车动力电池的发展目标(300~500 Wh kg-1)尚有较大差距.因此,研究开发新一代电池技术十分迫切[1].

Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries

Lithium(Li) metal is widely considered as a promising anode for next-generation lithium metal batteries(LMBs) due to its high theoretical capacity and lowest electrochemical potential. However, the uncontrollable formation of Li dendrites has prevented its practical application. Herein, we propose a kind of multifunctional electrolyte additives(potassium perfluorinated sulfonates) from the multi-factor principle for electrolyte additive molecular design(EDMD) view to suppress the Li dendrite growth. The effects of these additives are revealed through experimental results, molecular dynamics simulations and firstprinciples calculations. Firstly, K^(+)can form an electrostatic shield on the surface of Li anode to prevent the growth of Li dendrites. Secondly, potassium perfluorinated sulfonates can improve the activity of electrolytes as co-conductive salts, and lower the electro-potential of Li nucleation. Thirdly, perfluorinated sulfonate anions not only can change the Li^(+)solvation sheath structure to decrease the desolvation energy barrier and increase the ion migration rate, but also can be partly decomposed to form the superior solid electrolyte interphase(SEI). Benefited from the synergistic effects, an outstanding cycle life over250 h at 1 m A cm^(-2) is achieved in symmetric Li||Li cells. In particular, potassium perfluorinated sulfonate additives(e.g., potassium perfluorohexyl sulfonate, denoted as K+PFHS) can also contribute to the formation of high-quality cathode electrolyte interphase(CEI). As a result, Li||LiNi_(0.6)Mn_(0.2)Co_(0.2)O_(2) full cells exhibit significantly enhanced cycling stability. This multi-factor principle for EDMD offers a unique insight on understanding the electrochemical behavior of ion-type electrolyte additives on both the Li metal anode and high-voltage cathode.

Isolation and identification of genes expressed differentially in rice inflorescence meristem with suppression subtractive hybridization

A subtracted cDNA library of rice (Oryza sativa L.) inflorescence meristem (IM) was constructed using the suppression subtractive hybridization (SSH) method. The cDNAs of the rice shoot apical meristem (SAM) were used as 'driver' and inflorescence meristem (IM) as 'tester' in the experiment, respectively. Forty of 250 randomly chosen cDNA clones were identified by differential screening, which were IM-specific or IM-highly expressed. Most of the rice IM cDNAs cloned by SSH appear to represent rare transcripts, 40% of which were derived from truly differentially expressed genes. Of all the forty sequenced cDNA inserts, eleven contain the regions with 60%-90% identity to their homolog in GenBank, eighteen are expected to be new genes, only two correspond to published rice genes.

镍催化的卤代糖苷和卤代芳烃通过还原偶联制备芳香碳糖苷类化合物的简易方法

报道了在温和条件下通过镍和联吡啶催化的还原偶联反应,由C(1)-卤代糖苷和缺电子的芳基溴化物制备芳香糖苷类化合物的方法.运用该种方法可以由中等或高的α-选择性得到芳香碳糖苷类产物.包括富电子的芳香碘化物在内的多种卤代芳烃底物适用于该反应,产率在40%~95%之间.该方法可以放大到克级规模,并在此条件下将镍催化剂的用量减少到2 mol%.

Induction of Wnt signaling antagonists and p21-activated kinase enhances cardiomyocyte proliferation during zebrafish heart regeneration

Heart regeneration occurs by dedifferentiation and proliferation of pre-existing cardiomyocytes(CMs).However,the signaling mechanisms by which injury induces CM renewal remain incompletely understood.Here,we find that cardiac injury in zebrafish induces expression of the secreted Wnt inhibitors,including Dickkopf 1(Dkkl),Dkk3,secreted Frizzled-related protein 1(sFrpl),and sFrp2,in cardiac tissue adjacent to injury sites.Experimental blocking of Wnt activity via Dkkl overexpression enhances CM proliferation and heart regeneration,whereas ectopic activation of Wnt8 signaling blunts injury-induced CM dedifferentiation and proliferation.Although Wnt signaling is dampened upon injury,the cytoplasmic β-catenin is unexpectedly increased at disarrayed CM sarcomeres in myocardial wound edges.Our analyses indicated that p21-activated kinase 2(Pak2)is induced at regenerating CMs,where it phosphorylates cytoplasmic β-catenin at Ser 675 and increases its stability at disassembled sarcomeres.Myocardial-specific induction of the phospho-mimeticβ-catenin(S675E)enhances CM dedifferentiation and sarcomere disassembly in response to injury.Conversely,inactivation of Pak2 kinase activity reduces the Ser 675-phosphorylatedβ-catenin(pS675-β-catenin)and attenuates CM sarcomere disorganization and dedifferentiation・Taken together,these findings demonstrate that coordination of Wnt signaling inhibition and Pak2/pS675-βYatenin signaling enhances zebrafish heart regeneration by supporting CM dedifferentiation and proliferation.

Stabilizing the cycling stability of rechargeable lithium metal batteries with tris(hexafluoroisopropyl)phosphate additive

The application of rechargeable lithium metal batteries(LMBs)has been hindered by the fast growth of lithium dendrites during charge and the limited cycling life because of the decomposition of the electrolyte at the interface.Here,we have developed a non-flammable triethyl phosphate(TEP)-based electrolyte with tris(hexafluoroisopropyl)phosphate(THFP)as an additive.The polar nature of the C–F bonding and the rich CF3 groups in THFP lowers its LUMO energy and HOMO energy to help form a stable,Li F-rich solid electrolyte interphase(SEI)layer through the reduction of THFP and increases the binding ability of the PF6-anions,which significantly suppresses lithium dendrite growth and reduces the electrolyte decomposition.Moreover,THFP participates in the formation of a thin,C–F rich electrolyte interphase(CEI)layer to provide the stable cycling of the cathode at a high voltage.The symmetric Li||Li and full Li/NCM622 cells with THFP additive have small polarization and long cycling life,which demonstrates the importance of the additive to the application of the LMBs.

Enhanced protective immunity against SARS-CoV-2 elicited by a VSV vector expressing a chimeric spike protein

SARS-CoV-2 and SARS-CoV are genetically related coronavirus and share the same cellular receptor ACE2.By replacing the VSV glycoprotein with the spikes(S)of SARS-CoV-2 and SARS-CoV,we generated two replication-competent recombinant viruses,rVSVSARS-CoV-2 and rVSV-SARS-CoV.Using wild-type and human ACE2(hACE2)knock-in mouse models,we found a single dose of rVSV-SARS-CoV could elicit strong humoral immune response via both intranasal(i.n.)and intramuscular(i.m.)routes.Despite the high genetic similarity between SARS-CoV-2 and SARS-CoV,no obvious cross-neutralizing activity was observed in the immunized mice sera.In macaques,neutralizing antibody(NAb)titers induced by one i.n.dose of rVSV-SARS-CoV-2 were eight-fold higher than those by a single i.m.dose.Thus,our data indicates that rVSV-SARS-CoV-2 might be suitable for i.n.administration instead of the traditional i.m.immunization in human.Because rVSV-SARS-CoV elicited significantly stronger NAb responses than rVSV-SARS-CoV2 in a route-independent manner,we generated a chimeric antigen by replacing the receptor binding domain(RBD)of SARS-CoV S with that from the SARS-CoV-2.rVSV expressing the chimera(rVSV-SARS-CoV/2-RBD)induced significantly increased NAbs against SARS-CoV-2 in mice and macaques than rVSV-SARS-CoV-2,with a safe Th1-biased response.Serum immunized with rVSV-SARS-CoV/2-RBD showed no cross-reactivity with SARS-CoV.hACE2 mice receiving a single i.m.dose of either rVSV-SARS-CoV-2 or rVSV-SARSCoV/2-RBD were fully protected against SARS-CoV-2 challenge without obvious lesions in the lungs.Our results suggest that transplantation of SARS-CoV-2 RBD into the S protein of SARS-CoV might be a promising antigen design for COVID-19 vaccines.

Pseudo-concentrated electrolytes for lithium metal batteries

Lithium metal batteries suffer from short lifespans and low Coulombic efficiency (CE) due to the high reactivity of Li and the poor stability of the solid electrolyte interphase (SEI). Herein, we propose the concept of a pseudo-concentrated electrolyte (PCE) induced by an electron-deficient additive (4-pyridylboronic acid;4-PBA) to form a robust, LiF-rich SEI, thus addressing the above issues. Molecular dynamics simulations confirm that 4-PBA can increase the coordination number of PF6^(-) anions in the Li+ solvation sheath to achieve pseudo-concentrated LiPF6 in the electrolyte. Moreover, the 4-PBA can scavenge harmful PF5 decomposed from LiPF6 to stabilize the LiF-rich SEI. The resulting robust LiF-rich SEI promotes Li growth along the SEI/Li interface and represses the growth of Li dendrites. Thus, excellent performance is achieved, with a high CE of 97.1% for a Li||Cu cell at 1.0 ​mA ​cm^(−2), and over 950 cycles at 0.5 ​mA ​cm^(−2) for Li||Li symmetric cells with 1.0 ​wt% 4-PBA electrolyte. Meanwhile, the resulting stable boron-containing cathode electrolyte interphase enables Li||LiNi0·6Co0·2Mn0·2O_(2) (NCM622) cells to achieve excellent stability, with a capacity retention of 86.9% after 200 cycles.

Molecular barriers to direct cardiac reprogramming

Myocardial infarction afflicts close to three quarters of a million Americans annually, resulting in reduced heart function, arrhythmia, and frequently death. Cardiomy- ocyte death reduces the heart＇s pump capacity while the deposition of a non-conductive scar incurs the risk of arrhythmia. Direct cardiac reprogramming emerged as a novel technology to simultaneously reduce scar tissue and generate new cardiomyocytes to restore cardiac function. This technology converts endogenous cardiac fibroblasts directly into induced cardiomyocyte-like cells using a variety of cocktails including transcription factors, microRNAs, and small molecules. Although promising, direct cardiac reprogramming is still in its fledging phase, and numerous barriers have to be overcome prior to its clinical application. This review discusses current findings to optimize reprogramming efficiency, including reprogramming factor cocktails and stoichiometry, epigenetic barriers to cell fate reprogramming, incomplete conversion and residual fibroblast identity, requisite growth factors, and environmental cues. Finally, we address the current challenges and future directions for the field.

Lithology-controlled stress variations of Longmaxi shale–Example of an appraisal wellbore in the Changning area

The Longmaxi shale is an extensive,prolific unconventional play in southwestern China.Its development in the Changning area is affected by ineffective hydraulic fracturing(HF)stimulation,fault reactivation and casing damage.It is suspected that the stress contrast within and between the shale reservoirs and the formations above and below matters to hydraulic fracture propagation and reservoir stimulation.To this end,the Longmaxi shale in the Changning area deserves a dedicated quantification of the in situ stress state and its variations.In this study,we re-visit the available data from one of the play’s first appraisal wellbores(X01)for an integrated geomechanics study,focusing on profiling the stress across the Longmaxi and its adjacent formations.Combining geophysical logs and other stress indicators,we re-interpret its stress profile in the context of lithological variations.The resulting stress variations are modeled primarily through a viscoplastic stress relaxation framework,compared with the results via the frictional equilibrium and an elastic theory(the Extended Eaton model).We offer some discussions on the differences and similarities of these stress profiling methods,and examine their applicability to Longmaxi shale in the Changning area.Our objective is to connect the lithology-controlled stress variations to the first-order complexities(HF ineffectiveness and fault reactivation)that have been observed in the area to date.

Nickel-catalyzed reductive coupling of glucosyl halides with aryl/vinyl halides enabling β-selective preparation of C-aryl/vinyl glucosides

This work describes stereoselective preparation ofβ-C-aryl/vinyl glucosides via mild Ni-catalyzed reductive arylation and vinylation of C1-glucosyl halides with aryl and vinyl halides.A broad range of aryl halides and vinyl halides were employed to yield C-aryl/vinyl glucosides in 42%–93%yields.Good to excellentβ-selectivities were obtained for C-glucosides by using tridentate ligand.