Practical evaluation of prelithiation strategies for next-generation lithium-ion batteries

With the increasing market demand for high-performance lithium-ion batteries with high-capacity electrode materials,reducing the irreversible capacity loss in the initial cycle and compensating for the active lithium loss during the cycling process are critical challenges.In recent years,various prelithiation strategies have been developed to overcome these issues.Since these approaches are carried out under a wide range of conditions,it is essential to evaluate their suitability for large-scale commercial applications.In this review,these strategies are categorized based on different battery assembling stages that they are implemented in,including active material synthesis,the slurry mixing process,electrode pretreatment,and battery fabrication.Furthermore,their advantages and disadvantages in commercial production are discussed from the perspective of thermodynamics and kinetics.This review aims to provide guidance for the future development of prelithiation strategies toward commercialization,which will potentially promote the practical application of next-generation high-energy-density lithium-ion batteries.

Insights Into the Interfacial Degradation of High-Voltage All-Solid-State Lithium Batteries

Poly(ethylene oxide)(PEO)-based solid polymer electrolyte(SPE)is considered as a promising solid-state electrolyte for all-solid-state lithium batteries(ASSLBs).Nevertheless,the poor interfacial stability with high-voltage cathode materials(e.g.,LiCoO_(2))restricts its application in high energy density solid-state batteries.Herein,high-voltage stable Li_(3)AlF_(6) protective layer is coated on the surface of LiCoO_(2) particle to improve the performance and investigate the failure mechanism of PEO-based ASSLBs.The phase transition unveils that chemical redox reaction occurs between the highly reactive LiCoO_(2) surface and PEO-based SPE,resulting in structure collapse of LiCoO_(2),hence the poor cycle performance of PEO-based ASSLBs with LiCoO_(2) at charging voltage of 4.2 V vs Li/Li+.By sharp contrast,no obvious structure change can be found at the surface of Li_(3)AlF_(6)-coated LiCoO_(2),and the original layered phase was well retained.When the charging voltage reaches up to 4.5 V vs Li/Li+,the intensive electrochemical decomposition of PEO-based SPE occurs,leading to the constant increase of cell impedance and directly causing the poor performance.This work not only provides important supplement to the failure mechanism of PEO-based batter-ies with LiCoO_(2),but also presents a universal strategy to retain structure stability of cathode-electrolyte interface in high-voltage ASSLBs.

RECQL4 regulates DNA damage response and redox homeostasis in esophageal cancer

Objective:RECQL4(a member of the RECQ helicase family)upregulation has been reported to be associated with tumor progression in several malignancies.However,whether RECQL4 sustains esophageal squamous cell carcinoma(ESCC)has not been elucidated.In this study,we determined the functional role for RECQL4 in ESCC progression.Methods:RECQL4 expression in clinical samples of ESCC was examined by immunohistochemistry.Cell proliferation,cellular senescence,the epithelial-mesenchymal transition(EMT),DNA damage,and reactive oxygen species in ESCC cell lines with RECQL4 depletion or overexpression were analyzed.The levels of proteins involved in the DNA damage response(DDR),cell cycle progression,survival,and the EMT were determined by Western blot analyses.Results:RECQL4 was highly expressed in tumor tissues when compared to adjacent non-tumor tissues in ESCC(P<0.001)and positively correlated with poor differentiation(P=0.011),enhanced invasion(P=0.033),and metastasis(P=0.048).RECQL4 was positively associated with proliferation and migration in ESCC cells.Depletion of RECQL4 also inhibited growth of tumor xenografts in vivo.RECQL4 depletion induced G0/G1 phase arrest and cellular senescence.Importantly,the levels of DNA damage and reactive oxygen species were increased when RECQL4 was depleted.DDR,as measured by the activation of ATM,ATR,CHK1,and CHK2,was impaired.RECQL4 was also shown to promote the activation of AKT,ERK,and NF-k B in ESCC cells.Conclusions:The results indicated that RECQL4 was highly expressed in ESCC and played critical roles in the regulation of DDR,redox homeostasis,and cell survival.

Enhanced performance in the direct electrocatalytic synthesis of ammonia from N2 and H2O by an in-situ electrochemical activation of CNT-supported iron oxide nanoparticles

The direct electrocatalytic synthesis of ammonia from N2 and H2O by using renewable energy sources and ambient pressure/temperature operations is a breakthrough technology,which can reduce by over 90%the greenhouse gas emissions of this chemical and energy storage process.We report here an in-situ electrochemical activation method to prepare Fe2O3-CNT(iron oxide on carbon nanotubes)electrocatalysts for the direct ammonia synthesis from N2 and H2O.The in-situ electrochemical activation leads to a large increase of the ammonia formation rate and Faradaic efficiency which reach the surprising high values of 41.6μg mgcat^−1 h^−1 and 17%,respectively,for an in-situ activation of 3 h,among the highest values reported so far for non-precious metal catalysts that use a continuous-flow polymer-electrolytemembrane cell and gas-phase operations for the ammonia synthesis hemicell.The electrocatalyst was stable at least 12 h at the working conditions.Tests by switching N2 to Ar evidence that ammonia was formed from the gas-phase nitrogen.The analysis of the changes of reactivity and of the electrocatalyst characteristics as a function of the time of activation indicates a linear relationship between the ammonia formation rate and a specific XPS(X-ray-photoelectron spectroscopy)oxygen signal related to O2−in iron-oxide species.This results together with characterization data by TEM and XRD suggest that the iron species active in the direct and selective synthesis of ammonia is a maghemite-type iron oxide,and this transformation from the initial hematite is responsible for the in-situ enhancement of 3-4 times of the TOF(turnover frequency)and NH3 Faradaic efficiency.This transformation is likely related to the stabilization of the maghemite species at CNT defect sites,although for longer times of preactivation a sintering occurs with a loss of performances.

Modeling and stability analysis of social foraging swarms in multi-obstacle environment

In this article we specify an individual-based foraging swarm （i.e., group of agents） model with individuals that move in an n-dimensional multi-obstacle environment. The motion of each individual （i） is determined by three factors： i） attraction to the local object position （x^-io＋） which is decided by the local information about the individuals＇ position that individual i can find; ii） repulsion from the other individuals on short distances; and iii） attraction to the global object position （xgoal） or repulsion from the obstacles in the environment, The emergent behavior of the swarm motion is the result of a balance between inter-individual interaction and the simultaneous interactions of the swarm members with their environment. We study the stability properties of the collective behavior of the swarm based on Lyapunov stability theory. The simulations show that the swarm can converge to goal regions and diverge from obstacle regions of the environment while maintaining cohesive.

Distributed Filtering Algorithm Based on Tunable Weights Under Untrustworthy Dynamics

Aiming at effective fusion of a system state estimate of sensor network under attack in an untrustworthy environment, distributed filtering algorithm based on tunable weights is proposed. Considering node location and node influence over the network topology, a distributed filtering algorithm is developed to evaluate the certainty degree firstly. Using the weight reallocation approach, the weights of the attacked nodes are assigned to other intact nodes to update the certainty degree, and then the weight composed by the certainty degree is used to optimize the consensus protocol to update the node estimates. The proposed algorithm not only improves accuracy of the distributed filtering,but also enhances consistency of the node estimates. Simulation results demonstrate the effectiveness of the proposed algorithm.

Photoactive materials based on semiconducting nanocarbons——A challenge opening new possibilities for photocatalysis

This perspective paper introduces the concept that nanocarbons and related materials such as carbon dots are an interesting intrinsic photocatalytic semiconducting material, and not only a modifier of the existing (semiconducting) materials to prepare hybrid materials. The semiconducting properties of the nanocarbons, and the possibility to have the band gap within the visible-light region through defect band engineering, introduction of light heteroatoms and control/manipulation of the curvature or surface functionalization are discussed. These materials are conceptually different from the 'classical' semiconducting photocatalysts, because semiconductor domains with tuneable characteristics are embedded in a conductive carbon matrix, with the presence of various functional groups (as C=0 groups) enhancing charge separation by trapping electrons. These nanocarbons open a range of new possibilities for photocatalysis both for energetic and environmental applications. The use of nanocarbons as quantum dots and photo luminescent materials was also analysed. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Coil-to-Stretch Transition of Binder Chains Enabled by“Nano-Combs”to Facilitate Highly Stable SiO_(x) Anode

The commercialized binder carboxymethyl cellulose sodium(CMC-Na)is considered unsuitable for micro-sized SiO_(x) anode as it cannot endure the large volume change to retain the conductive network during repeated charge/discharge cycles.Herein,a small amount of silicon nanoparticles(SiNPs)is added during slurry preparation process as“nano-combs”to unfold the convoluted CMC-Na polymer chains so that they undergo a coilto-stretch transition by interaction between polar groups(e.g.,-OH,-COONa)of polymer and SiNPs’large surface.Through maximizing the utilization of binders,a uniform conductive network is constructed with increased interfacial contact with micro-sized SiO_(x).As a result,the SiO_(x) electrode with optimized(10 wt%)SiNPs addition shows significantly improved initial capacity and cycling performance.Through revisiting CMCNa,a currently deemed unqualified binder in SiO_(x) anode,this work gives a brand-new perspective on the failing mechanism of Si-based anode materials and an improving strategy for electrode preparation.

基于多尺度图像重建的硅负极结构演化定量分析

为了深入了解硅基负极在循环过程中的结构演化,本文首次应用电极和颗粒水平多尺度的三维图像重建技术,对微米硅负极在电循环过程中的结构进行了可视化的定量表征;通过分析电解液中氟代碳酸乙烯酯(FEC)添加剂的影响,生动展示了硅负极的结构/成分演变与电化学性能之间的联系.利用聚焦离子束和扫描电子显微镜(FIB-SEM)技术,对电极中的三种组分(硅活性颗粒,非活性组分和孔隙)的体积和形状变化进行了定量的分析,并统计了循环过程中硅颗粒的平均尺寸.结合电化学分析结果表明,电解液FEC添加剂可以在硅负极的循环早期形成稳定的固态电解质界面(SEI),从而有效抑制硅颗粒的巨大体积膨胀和粉化现象,提高电极的循环稳定性.本文提出的方法为具有类似体积膨胀问题的电极体系提供了新的研究视角.

Inhibitory effects of chitosan on superoxide anion radicals and lipid free radicals

With the electron spin resonance (ESR) technique, the inhibitory effects of chitosan on superoxide anion radicals and linoleic acid lipid radicals were found. The inhibitory ratio E for these two kinds of radicals is in proportion to the concentration of chitosan. It was also observed that E for linoleic acid lipid radicals increased with the increase of the degree of deacetylation and decreased with the increase of the molecular weight of chitosan.

Polymeric Wetting Matrix for a Stable Interface between Solid-state Electrolytes and Li Metal Anode

Succinonitrile(SN)based solid-state electrolytes(SSEs)have potential applications in lithium(Li)batteries due to their ease of preparation and high ionic conductivity at room temperature.Here,a novel SSE consisting of poly(vinylidene fluoride-hexafluoropropy-lene)(PVDF-HFP),poly(methyl methacrylate)(PMMA)and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3) with SN is fabricated,where PMMA is added to serve as a polymer matrix for better wettability of SN.Due to the addition of PMMA,improved room-temperature ionic conductivity of the SSE is resulted.More importantly,better interfacial contact as well as more stable solid-state electrolyte(SEI)layer between SSE and Li anode can be also obtained.As a result,homogeneous and dendrite-free Li plating can be achieved for over 1000 h in Li symmetric cells.When coupled with LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2) cathode and Li anode,the proposed SSE delivers excellent cycling stability and rate capability in full-cells.By implementing SSEs with a polymeric wetting agent,this work provides fresh perspectives on stabilizing the interface between SSEs and Li metal anodes.

Unidirectional propagation of water waves near ancient Luoyang Bridge

Metasurfaces and metagratings offer new platforms for electromagnetic wave control with significant responses.However,metasurfaces based on abrupt phase change and resonant structures suffer from the drawback of high loss and face challenges when applied in water waves.Therefore,the application of metasurfaces in water wave control is not ideal due to the limitations associated with high loss and other challenges.We have discovered that non-resonant metagratings exhibit promising effects in water wave control.Leveraging the similarity between bridges and metagratings,we have successfully developed a water wave metagrating model inspired by the ancient Luoyang Bridge in China.We conduct theoretical calculations and simulations on the metagrating and derive the equivalent anisotropic model of the metagrating.This model provides evidence that the metagrating has the capability to control water waves and achieve unidirectional surface water wave.The accuracy of our theory is strongly supported by the clear observation of the unidirectional propagation phenomenon during simulation and experiments conducted using a reduced version of the metagrating.It is the first time that the unidirectional propagation of water waves has been seen in water wave metagrating experiment.Above all,we realize the water wave metagrating experiment for the first time.By combining complex gratings with real bridges,we explore the physics embedded in the ancient building—Luoyang Bridge,which are of great significance for the water wave metagrating design and provide a new method for analyzing the effects of water waves on bridges.At the same time,this discovery also provides a new idea for ocean cargo transportation,ocean garbage cleaning,and the development and protection of ancient bridges.