High-Performance 3D Li-B-C-Al Alloy Anode and its Twofold Li Electrostripping and Plating Mechanism Revealed by Synchrotron X-Ray Tomography

The uncontrollable Li electrostripping and plating process that results in dendritic Li growth and huge volume change of Li anode limits the practicality of Li metal batteries(LMBs).To simultaneously address these issues,designing three-dimensional(3D),lithiophilic and mechanically robust electrodes seems to be one of the cost-effective strategies.Herein,a new 3D Li-B-C-Al alloy anode is designed and fabricated.The prepared 3D alloy anode exhibits not only superior lithiophilicity that facilitates uniform Li nucleation and growth but also sufficient mechanical stability that maintains its structural integrity.Superior performance of the prepared 3D alloy is demonstrated through comprehensive electrochemical tests.In addition,non-destructive and 3D synchrotron X-ray computed tomography(SX-CT)technique is employed to investigate the underlying working mechanisms of the prepared alloy anode.A unique twofold Li electrostripping and plating mechanism under different electrochemical cycling conditions is revealed.Lastly,improved performance of the full cells built with the 3D alloy anode and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathode corroborate its potential application capability.Overall,the current work not only showcases the superiority of the 3D alloy as potential anode material for LMBs but also provides fundamental insights into its underlying working mechanisms that may further propel its research and development.

Acid-pickling plates and strips speed control system by microwave heating based on self-adaptive fuzzy PID algorithm

Double self-adaptive fuzzy PID algorithm-based control strategy was proposed to construct quasi-cascade control system to control the speed of the acid-pickling process of titanium plates and strips. It is very useful in overcoming non-linear dynamic behavior, uncertain and time-varying parameters, un-modeled dynamics, and couples between the automatic turbulence control (ATC) and the automatic acid temperature control (AATC) with varying parameters during the operation process. The quasi-cascade control system of inner and outer loop self-adaptive fuzzy PID controller was built, which could effectively control the pickling speed of plates and strips. The simulated results and real application indicate that the plates and strips acid pickling speed control system has good performances of adaptively tracking the parameter variations and anti-disturbances, which ensures the match of acid pickling temperature and turbulence of flowing with acid pickling speed, improving the surface quality of plates and strips acid pickling, and energy efficiency.

Variation analysis of ultimate pullout capacity of shallow horizontal strip anchor plate with 2-layer overlying soil based on nonlinear M-C failure criterion

Based on the nonlinear Mohr-Coulomb failure criterion and an associated flow rule,a kinematic admissible velocity field of failure mechanism of the 2-layer soil above a shallow horizontal strip anchor plate is constructed.The ultimate pull-out force and its corresponding failure mechanism through the upper bound limit analysis according to a variation principle are deduced.When the 2-layer overlying soil is degraded into single-layer soil,the model of ultimate pullout force could also be degraded into the model of single-layer soil.And the comparison between results of single-layer soil variation method and those calculated by rigid limit analysis method proves the correctness of our method.Based on that,the influence of changes of geotechnical parameters on ultimate pullout forces and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are analyzed.The results show that the ultimate pull-out force and failure mechanism of a shallow horizontal strip anchor with the 2-layer soil above are affected by the nonlinear geotechnical parameters greatly.Thus,it is very important to obtain the accurate geotechnical parameters of 2-layer soil for the evaluation of the ultimate pullout capacity of the anchor plate.

高强耐蚀1420Al-Li/Mg-9Li/1420Al-Li复合板制备及力学性能

采用高强耐蚀超轻1420 Al-Li合金作为覆板,通过一道次热轧制备了1420Al-Li/Mg-9Li/1420Al-Li复合板,研究了不同压下量、450℃热轧复合板界面的微观组织和力学性能。结果表明:当轧制压下量为35%时,复合板仅为部分结合—机械结合+冶金结合,界面无化合物生成,复合板的抗拉强度为236 MPa,伸长率为26%;当轧制压下量为50%时,复合板实现完全冶金结合,无界面化合物生成,复合板的抗拉强度高达272 MPa,伸长率为14%,在提高抗腐蚀性的同时,大幅提高了Mg-9Li合金的强度。

Dendrite‑Free and Stable Lithium Metal Battery Achieved by a Model of Stepwise Lithium Deposition and Stripping

The uncontrolled formation of lithium(Li)dendrites and the unnecessary consumption of electrolyte during the Li plating/stripping process have been major obstacles in developing safe and stable Li metal batteries.Herein,we report a cucumber-like lithiophilic composite skeleton(CLCS)fabricated through a facile oxidationimmersion-reduction method.The stepwise Li deposition and stripping,determined using in situ Raman spectra during the galvanostatic Li charging/discharging process,promote the formation of a dendrite-free Li metal anode.Furthermore,numerous pyridinic N,pyrrolic N,and CuxN sites with excellent lithiophilicity work synergistically to distribute Li ions and suppress the formation of Li dendrites.Owing to these advantages,cells based on CLCS exhibit a high Coulombic efficiency of 97.3%for 700 cycles and an improved lifespan of 2000 h for symmetric cells.The full cells assembled with LiFePO_(4)(LFP),SeS_(2) cathodes and CLCS@Li anodes demonstrate high capacities of 110.1 mAh g^(−1) after 600 cycles at 0.2 A g^(−1) in CLCS@Li|LFP and 491.8 mAh g^(−1) after 500 cycles at 1 A g^(−1) in CLCS@Li|SeS2.The unique design of CLCS may accelerate the application of Li metal anodes in commercial Li metal batteries.

Self-Adaptive and Electric Field-Driven Protective Layer with Anchored Lithium Deposition Enable Stable Lithium Metal Anode

Lithium metal battery has great development potential because of its lowest electrochemical potential and highest theoretical capacity.However,the uneven deposition of Li^(+)flux in the process of deposition and stripping induces the vigorous growth of lithium dendrites,which results in severely battery performance degradation and serious safety hazards.Here,the tetragonal BaTiO3 polarized by high voltage corona was used to build an artificial protective layer with uniform positive polarization direction,which enables uniform Li^(+)flux.In contrast to traditional strategies of using protective layer,which can guide the uniform deposition of lithium metal.The ferroelectric protective layer can accurately anchor the Li^(+)and achieve bottom deposition of lithium due to the automatic adjustment of the electric field.Simultaneously,the huge volume changes caused by Li^(+)migration change of the lithium metal anode during charging and discharging is functioned to excite the piezoelectric effect of the protective layer,and achieve seamless dynamic tuning of lithium deposition/stripping.This dynamic effect can accurately anchor and capture Li^(+).Finally,the layer-modified Li anode enables reversible Li plating/stripping over 1500 h at 1 mA cm^(-2)and 50℃in symmetric cells.In addition,the assembled Li-S full cell exhibits over 300 cycles with N/P≈1.35.This work provides a new perspective on the uniform Li^(+)flux at the Li-anode interface of the artificial protective layer.

Development of Continuous Coating and Plating Strip Steel

The development trend of coated and plated technology for continuous strip steels,which include hot dip plating,electroplating,organic coating and vacuum plating technology,were summarized.

BUCKLING ANALYSIS UNDER COMBINED LOADING OF THIN-WALLED PLATE ASSEMBLIES USING BUBBLE FUNCTIONS

Bubble functions are finite element modes that are zero on the boundary of the element but nonzero at the other point. The present paper adds bubble functions to the ordinary Complex Finite Strip Method(CFSM) to calculate the elastic local buckling stress of plates and plate assemblies. The results indicate that the use of bubble functions greatly improves the convergence of the Finite Strip Method(FSM) in terms of strip subdivision, and leads to much smaller storage required for the structure stiffness and stability matrices. Numerical examples are given, including plates and plate structures subjected to a combination of longitudinal and transverse compression, bending and shear. This study illustrates the power of bubble functions in solving stability problems of plates and plate structures.

LiC_(6)在复合锂负极中的作用、形成和表征

锂金属电池(LMB)被认为是最有前景的下一代储能系统之一。然而,其实际应用存在极大的体积变化和锂枝晶的形成等重大挑战。为了应对这些挑战,引入炭材料的复合锂负极因其优异的化学和电化学稳定性以及在重复循环过程中的优异机械强度引起了极大关注。本文旨在全面概述锂化石墨(LiC_(6))的形成及其在锂沉积和剥离过程中在体相和界面区域的作用。在体相中,LiC_(6)表现出优异的亲锂性能,降低了锂成核的过电位并促进锂的均匀沉积。当在电极-电解质界面引入LiC_(6)时,它通过充当缓冲层来增强电极和电解质之间的接触,从而降低界面阻抗。最后,本文评述了锂碳复合负极发展的前景和挑战。

Convergence and exact solutions of spline finite strip method using unitary transformation approach

The spline finite strip method （FSM） is one of the most popular numerical methods for analyzing prismatic structures. Efficacy and convergence of the method have been demonstrated in previous studies by comparing only numerical results with analytical results of some benchmark problems. To date, no exact solutions of the method or its explicit forms of error terms have been derived to show its convergence analytically. As such, in this paper, the mathematical exact solutions of spline finite strips in the plate analysis are derived using a unitary transformation approach （abbreviated as the U-transformation method herein）. These exact solutions are presented for the first time in open literature. Unlike the conventional spline FSM which involves assembly of the global matrix equation and its numerical solution, the U-transformation method decouples the global matrix equation into the one involving only two unknowns, thus rendering the exact solutions of the spline finite strip to be derived explicitly. By taking Taylor＇s series expansion of the exact solution, error terms and convergence rates are also derived explicitly and compared directly with other numerical methods. In this regard, the spline FSM converges at the same rate as a non-conforming finite element, yet involving a smaller number of unknowns compared to the latter. The convergence rate is also found superior to the conventional finite difference method.

Correlating electrochemical performance and heat generation of Li plating for lithium-ion battery with fluoroethylene carbonate additive

1.Introduction With the superior performance of high energy density,lightweight and long life span,lithium-ion battery(LIB)are perceived as an attractive and reliable power source for modern-used portable electronics,ecofriendly electric vehicles and power distribution,and thereby a remarkable solution to assuage energy dependence on fossil fuel and environmental concern.Nevertheless,the unexpected Li plating together with the Li dendrites growth on graphite anode surface has been a profound hindrance to the practical application of LIB,of which induces inferior Coulombic efficiency,poor lifespan and safety concern[1].

DYNAMIC RESPONSE OF PLATES DUE TO MOVING VEHICLES USING FINITE STRIP METHOD

Dynamic response of beam-like structures to moving vehicles has been extensively studied. However, the study on dynamic response of plates to moving vehicles has so far received but scant attention. A plate-vehicle strip for simulating the interaction between a rectangular plate and moving vehicles was described. For the portion of strips that are in direct contact with the moving vehicles, the plate-vehicle strips were employed. Conventional plate finite strips were used to model the portion of strips that are not directly under the action of moving vehicles. In the analysis, each moving vehicle is idealized as a one-foot dynamic system with tire unsprung mass and sprund mass interconnected by a spring and a dashpot. The numerical results obtained from the proposed method agree well with available results.

New Insight on Graphite Anode Degradation Induced by Li-Plating

Graphite is the dominant anode material for lithium-ion batteries;however,it still suffers from Li-plating when charging fast or at low temperature,and Liplating is associated with performance fading and safety concerns.Herein,we clarify the mechanism of lithium evolution from graphite particles by overlithiation cycle test,in-situ XRD,and titration gas chromatography.We observe that the graphite intercalation compounds(GICs,LiC_(12) and LiC_(6)e.g.)gradually become inactive and wrapped by dead lithium or side reaction sediments,while the rate of this degradation will be accelerated as the overpotential of Liplating is decreased after initial Li metal nucleation.This understanding is contradictory to the popular one that the degradation of graphite anode after Li plating is mainly caused by the inferior SEI and dead Li induced hindering of Li-ion intercalation.The isolation of lithiated graphite particles leading to the fast vanishing of Li insertion/deintercalation process in graphite anodes.We further study the insertion/deintercalation vanishing process at low temperature and high rates,respectively.This work provides a insight on graphite anode degradation induced by Li-plating,and the new understanding can be used to guide the design of advanced materials and electrodes to avoid Li-plating and achieve extreme fast while safe charging.

THE SOLUTION OF RECTANGULAR PLATES WITH LARGE DEFLECTION BY SPLINE FUNCTIONS

In this paper, Von Karman's set of nonlinear equations for rectangular plates with large deflection is divided into several sets of linear equations by perturbation method, the dimensionless center deflection being taken as a perturbation parameter. These sets of linear equations are solved by the spline finite-point (SFP) method and by the spline finite element (SFE) method. The solutions for rectangular plates having any length-to-width ratios under a uniformly distributed load and with various boundary conditions are presented, and the analytical formulas for displacements and deflections are given in the paper. The computer programs are worked out by ourselves. Comparison of the results with those in other papers indicates that the results of this paper are satisfactorily better.

Near-stoichiometric Ti:LiNbO3 strip waveguide with varied substrate refractive index in waveguide layer

We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.

Steckel mill as a green steel strip and plate production technology

The Steckel mill,a long established solution for the economical production of relatively small volumes of hot rolled strip,has been rejuvenated in recent years by a range of new applications,boosted by the need of improving the energetic efficiency of the rolling process.The traditional advantages of the Steckel mill in terms of flexibility and reduced capital and operational costs are now enhanced by technological developments that have significantly expanded its application range into the combined production of strip and plate and improved the product quality.The increased awareness of the necessity of a sustainable growth in the steel industry has stimulated the development of process solutions with an improved efficiency in the use of natural resources,lower carbon emissions and increased yield.Modern Steckel mills are an adequate response to the trend towards low energy strip and plate production,in particular in their plate-Steckel mill variant.Siemens VAI have played a key role in the innovation and transformation of the Steckel mill concept,with a number of recent installations,presented in this paper from the point of view of their contribution to the development of greener steel rolling technologies.

基于弛豫时间归一化参数的锂离子电池析锂量检测方法

析锂作为锂离子电池使用的主要安全隐患之一,不仅会造成电池的寿命极速衰减,还可能引发燃烧、爆炸等灾难性后果。随着近年来快充技术的发展,对于锂离子电池析锂情况的诊断需求愈发迫切。针对现有定量方法诊断精度严重受制于测试温度的问题,提出了一种基于弛豫时间归一化表征的改进电压释放法。从理论上分析了“析锂量与温度”因素组合对电池电压释放行为的影响规律。在此基础上,将释放阶段弛豫电压差分曲线峰值处所对应时间,与完全释放时间作比,得到“弛豫时间归一化参数”这一温度脱敏的析锂量诊断无量纲特征参数。分别利用多物理模型仿真与实验测试,验证了新方法诊断的准确性与温度适应性。

引线框架用高性能铜合金板带材及制备工艺

电子信息产业的飞速发展,对铜及铜合金产品性能提出了更高的要求,其中集成电路封装用引线框架材料代表了铜合金板带材发展的较高水平。本文对近年来引线框架用高性能铜合金板带材及制备工艺进行了综述,介绍了国内外高性能铜合金板带材料的成分和制备加工技术及发展过程,并对其未来发展趋势进行了展望,提出未来高性能铜板带材性能将朝着抗拉强度为700 MPa、导电率为70%IACS的目标发展,其制备工艺将向着智能化、绿色化、高效化等方向发展。

Deep eutectic solvent-based polymer electrolyte for solid-state lithium metal batteries

Poly(ethylene) oxide(PEO)-based electrolytes have been widely studied for solid-state lithium batteries while their ionic conductivity and lithium-ion transference number still need to be further improved.Herein, using the combined experimental and theoretical approach, we demonstrate a novel, solidstate PEO-deep eutectic solvent(DES) electrolyte for the first time. We found that the in situ formation of DES can reduce the crystallinity of PEO matrix and more Li+ions can move freely owing to the weakened coordination between ether oxygens and Li-ions. Besides, we show that more Li+ions can be dissociated from Li salts in PEO-DES electrolyte using the molecular dynamics simulations. Such liquid-free PEO-DES electrolytes showed good ionic conductivity(2.1 × 10^(-4) S cm^(-1)) which is 160% higher than that of conventional PEO-Li TFSI(8.1 × 10^(-5) S cm^(-1)) electrolyte at 60 ℃. Additionally, the PEO-DES electrolyte showed 136% increase of Li-ion transference number(0.33) compared with ionic liquid-doped PEO-Li TFSI(0.14) at 60 ℃. Moreover, the PEO-DES exhibited good compatibility with Li metal and stable Li plating/stripping behavior with little morphology change of Li metal. This research also provides new insights into the enhancement mechanisms of novel polymer electrolytes, improving our fundamental understanding of critical challenges that have impeded the adoption of solid-state lithium metal batteries.

Homogenous lithium plating/stripping regulation by a mass-producible Zn particles modified Li-metal composite anode

A stable lithium-metal anode is critical for high performance lithium-metal batteries. However, heterogeneous Li plating/stripping may induce lithium dendrites formation on bare lithium-metal anode, which lowers the cell Coulombic efficiency and weakens battery safety. We found that bare Li metal surface becomes bumpy and cratered with numerous pits formation during Li stripping. These pits enhance electric field distortion and heterogeneous ion distribution during plating. Li plating preferentially happens on the edge of the pits, intensifying the voltage variation and Li dendrites growth, which leads to the cell rapid death or separator piercing. Herein, we propose a facile and mass-producible method to homogenize Li plating/stripping via adding lithiophilic particles into Li metal. Zinc particles were uniformly pressed in Li metal by a facile and scalable physical strategy of “rolling”, and transformed into LiZn alloy in situ through Li-Zn alloying at room temperature in a few minutes. The critical role of modified LiZn/Li composite anode in stabilizing electrode surface was revealed by both electrochemical test and simulation. Compared with bare Li anode, the evenly dispersed LiZn alloy particles in Li metal can effectively regulate the Li plating/stripping on electrode surface, reducing deepness of pits during stripping and directionally inducing Li plating to maintain electrode surface stability. On this basis, the pits depth of LiZn/Li composite during Li stripping is reduced to ∼ 15 μm, which is much shallower than that of bare Li metal of ∼ 40 μm. The LiZn/Li composite electrode can stably cycle for 600 h under Li plating/stripping capacity of 1 mAh·cm−2 and current density of 1 mA·cm−2 without any short circuit. Furthermore, assembled LiZn/Li||LiFePO4 full cell presents better cycling stability and rate performances than that of based on bare Li anode.