Lithium Alloy Research Articles

Conductive and Porous Silicon Nanowire Anodes for Lithium Ion Batteries

Silicon nanowires (SiNWs) were prepared by chemically etching silicon wafers with silver nanoparticles. Their electrical conductivities and porosities were tuned by adjusting the doping concentration of silicon wafers from which the SiNWs were prepared. Porosity of the SiNWs were proportional to doping concentrations of the mother wafer because the dopant population provides nucleation sites for etching. The electrical conductivities of the doped SiNWs were 100 times higher than those of the intrinsic SiNW. However, there was no difference in the conductivity between two different doping level SiNWs (Na = 2.7 × 1015 and 5.7 × 1019) due to the trade-off between porosity and the intrinsic conductivity of the solid backbone. The doping-dependent properties of SiNWs determined the capacity, stability and kinetics of the lithium alloying reaction of the SiNWs. The medium-level doping SiNWs, characterized by a mechanically obust porous structure, showed the most improved electrochemical performances in a full cell of a lithium manganese oxide || SiNW battery as a result of the balanced trade-off between coulombic efficiency and capacity retention.

Corrosion resistance investigation of vanadium alloys in liquid lithium

A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10–3 wt %) of vanadium and vanadium alloys (V–1.86Ga, V–3.4Ga–0.62Si, V–4.81Ti–4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 1022 m–2 at an irradiation temperature of ~400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

Surface tension of lead–bismuth eutectic melts with lithium

The temperature and concentration dependences of the surface tension of lithium alloys (up to 33.1 at %) on the basis of a eutectic melt of Pb44.7Bi55.3 are measured in the range from the liquidus temperature to 700 K. The margin of error of the experiments was ~2%. Lithium has a low surface activity in the Pb44.7Bi55.3 eutectic melt, which agrees with the criteria of the surface activity of components in binary liquid metal melts.

Surface tension of lead–lithium melts

The temperature and concentration dependences of the surface tension of lithium alloys based on lead are experimentally determined for the first time in a field of compositions with up to 20 at % lithium in lead in the temperature range from the liquidus up to 700 K. The isotherm of surface tension of the studied alloys in the range of compositions with ~10 at % Li in lead contains a minimum, as does the adsorption isotherm of lithium in the sub-eutectic area of PbLi compounds.

Effects of copper additive on micro-arc oxidation coating of LZ91 magnesium-lithium alloy

Abstract The improvement in corrosion resistance for magnesium–lithium alloys in an aggressive environment is an important issue for their widespread application. In this research, the different colors of ceramic coatings are developed by micro-arc oxidation technology in order to protect the surfaces of LZ91 magnesium–lithium alloy using electrolytes containing different concentrations of copper compound. The MAO coatings are compared based on their thicknesses, porosities, surface compositions and corrosion performances. The surface morphology, cross-section and chemical compositions of phosphate coatings were investigated via scanning electron microscopy (SEM) accompanied by energy-dispersive X-rays. The corrosion performance and porosity of the coatings were evaluated by electrochemical characterization which was performed in a 3.5% NaCl solution at 25 °C. The findings showed that the color of the coating fabricated by the MAO process, with the addition of 3% and 5% Cu in the base electrolyte, changed from brown to dark brown. The coating thickness increased and became more porous with increasing concentrations of copper ions in the base electrolyte. The corrosion resistance of the LZ91 alloy was significantly improved after being treated with the micro-arc oxidation process.

Behaviour of hydrogenated lead–lithium alloy

Eutectic Pb–Li (lithium 15.6 at.%) alloy has been tested by means of thermogravimetric analysis under different hydrogenation conditions in the temperature range 25–650 °C. The melting temperature of the material changes irreversibly after the first heating ramp, from that of the eutectic alloy (240 °C) to that of pure lead (330 °C). The capacity to upload hydrogen depends on the thermal cycling and on the humidity presence. Particularly, it has observed that the presence of water traces in the environment leads to the formation of lithium hydroxide. This reaction affects dramatically the hydrogen uploading of the Pb–Li. Such a behavior is discussed in details by considering the change of weight of the Pb–Li along hydrogenation and thermal cycling.

Challenges and Issues Facing Lithium Metal for Solid State Rechargeable Batteries

Research on lithium metal combined with polymer electrolyte in lithium rechargeable batteries was started in 1979. Since that time, lithium battery research has expanded worldwide. Several new polymers, solid electrolytes and ionic liquids with improved conductivity were identified. These advances resulted from a better understanding of the major parameters controlling ion migration, such as favorable polymer structure, phase diagrams between solvating polymers and lithium salts, and the development of new lithium counter-anions. In spite of the progress so far, the quest for a highly conductive dry polymer at room temperature is still not available. However, effort is continuing, and all-lithium polymer battery (LPB) developers presently face the challenge of whether to heat the polymer electrolyte to enable high-power performance, as required for electric vehicles and energy storage. LPB developers have explored both the high-temperature and low-temperature options. The commercial use of lithium metal/polymer batteries has been delayed because of the adverse effects of dendrites on the surface of the lithium electrodes, and the difficulty in finding a polymer that has both the mechanical strength and ionic conductivity required in a solid electrolyte. However, recent strategies have emerged to overcome these difficulties, and now these batteries are currently an option for different applications, including electric cars.In this presentation, we review these strategies and discuss the different promising routes that should result in further progress on lithium metal/polymer batteries in the near future. This presentation also discusses the challenges and opportunities in developing thin lithium negative electrodes with stable SEI layers for three battery technologies using: All solid-state Li-sulfur batteries Rechargeable lithium batteries containing dry polymer and ionic liquid-polymer electrolytes 3. Li-air batteries. In addition, we will discuss the safety of lithium, dendrite mechanism, interface phenomena, side reactions, protection of lithium metal, and lithium alloys that are relevant to lithium batteries. Acknowledgement: The author thanks the SCE IREQ and LTE Shawinigan teams for helpful discussion.

Formation of a Lithium-Plated Reference Electrode in Lithium-Ion Batteries: Characterization Using Dynamic Impedance and Simulation Using an Electrochemical Model

Reference electrodes (REs), enabling one to differentiate the contributions of each electrode, have been widely used in the research of electrochemical systems, such as lithium-ion batteries (LIBs). Metallic lithium or lithium alloy (Li-Sn, Li-Al) is the usual material of choice for REs in LIBs. A typical approach is to form a layer of metallic lithium onto a stable substrate by in-situ plating, termed as lithium-plating method [1][2]. In the present study, a copper-wire based RE is embedded into a 2 Ah laminated LIB, and its formation process, crucial to stability of the RE, is scrutinized. During the formation process, the RE is set as the working electrode, and the positive and negative electrodes are used as the counter electrode successively to obtain a both-side-plated RE. Dynamic electrochemical impedance spectroscopy (DEIS) is used as a characterization tool. Being dynamic means that the impedance measurements are performed while there is a DC current between the RE and the counter electrode [3][4]. Figure 1. (a) shows the evolution of DEIS during the whole formation process. It is revealed that a new semi-circle attributed to the emergence of the solid/electrolyte interphase (SEI) film manifests immediately at the moment the formation starts. Ohmic resistance, SEI film resistance and charge transfer resistance all gradually decrease during the formation process, and arrive at their constant values after 2×104s. In comparison with the potential monitoring, DEIS allows better characterization of the formation process with higher sensitivity and resolution. To understand the above phenomena, a two-dimensional (2D) model, accounting for growth of the RE size and concomitant decrease of the electrolyte porosity [5], is developed. Figure. 1 (b) shows non-uniform current distribution during the plating process with the positive electrode as the counter electrode. As expected, the plating current concentrates on the positive-electrode-facing side. Consequently, a thicker lithium layer is deposited onto this side. Impedance simulation results are compared with the experimental DEIS results. Based on this model, a multistep plating strategy is optimized to improve the stability and durability of RE. Key words Reference electrode; Lithium plating; Electrochemical impedance spectroscopy; Electroplating model; Solid/electrolyte interphase Reference: [1]. D. P. Abraham, S. D. Poppen, A. N. Jansen, J. Liu and D. W. Dees, ELECTROCHIM ACTA, 49, 4763 (2004). [2]. A. N. Jansen, D. W. Dees, D. P. Abraham, K. Amine and G. L. Henriksen, J POWER SOURCES, 174, 373 (2007). [3]. J. Huang, J. Zhang, Z. Li, S. Song and N. Wu, ELECTROCHIM ACTA, 131, 228 (2014). [4]. J. Huang, H. Ge, Z. Li and J. Zhang, ELECTROCHIM ACTA, 176, 311 (2015). [5]. J. Newman and W. Tiedemann, J ELECTROCHEM SOC, 140, 1961 (1993). Figure 1

Realizing 200mAh g-1 Lithium Manganese Oxide Spinel in Lithium Ion Battery with Prelithiated Anode

At present, the global market size of Li ion battery is dramatically increasing as its application in large scale system such as electric vehicle (EV) and energy storage system (ESS) expands intensely. Accordingly, the development of high-energy-density battery for their application is urgently needed. Today, energy density of Li ion battery largely depends on the specific capacity of cathode active material. The specific practical capacity of conventional cathode active materials such as LMO (Lithium Manganese Oxide Spinel, 4V region), LNMC (Lithium Nickel Manganese Cobalt Layered Oxide), and LFP (Lithium Iron Phosphate Olivine) is 100-170 mAh/g and the utilization of cathode active materials of even higher specific capacity is essential for the development of high-energy-density battery.Cathode active materials such as sulfur, oxygen, LMO (3+4V region) have theoretically very high specific capacity (270 – 3800 mAh/g), however, cannot be adopted in today’s Li ion battery industry because in their structure they do not possess lithium which is vital for electrochemical reaction in Li ion battery. To utilize these non-lithiated cathode active materials, additional lithium must be provided to the cell. Li half-cell where Li-foil is used as the anode in the cell could be a candidate, however, the Li dendrite growth problem which might lead to battery explosion should be precedently solved for practical application. More desirable and rather easily applicable solution is the prelithiation strategy in which anode or cathode is chemically lithiated (via lithium intercalation or alloying) by short-circuit reaction between the electrode and lithium source such as lithium foil, gas or powder. The prelithiation of anode is preferred because the cathode prelithiation might yield safety problem with excessive generation of heat of reaction. In this study, we propose an elegant prelithiation mechanism in graphite anode based on the results of electrochemical reaction and physico-chemical analyses. We demonstrate the prelithiation methodology that is directly applicable in practice with high prelithiation yield (efficiency) by controlling the relevant important variables. We also show that the developed prelithiation methodology can be applied for designing and operating full cell battery in which non- (or partially) lithiated LMO is adopted as cathode active material, which delivers ~200 mAh/g in 3+4V region with good cycle capability.

A study of the relationship between the electrochemical behavior of magnesium–lithium alloys in phosphate media and their phosphating treatment

The electrochemical behavior of magnesium–lithium alloys of MA 21 and IMV 12 types in the solutions of moderately acidic phosphates (0.34 M H3PO4 + 0.17 M HNO3 + NaOH, pH 2.7) containing fluoride ions (0.01–0.09 mol/L)) is studied in the context of phosphating treatment. The relationship of the results of electrochemical studies with the results of phosphating of the given alloys is determined. The dependence of the electrochemical activity of alloys on their nature is shown. The rate of stationary electrochemical process determines the rate of the formation of phosphate films with modified properties and structure on magnesium–lithium alloys.

Evaluation of the Electrochemical Properties of Crystalline Copper Antimonide Thin Film Anodes for Lithium Ion Batteries Produced by Single Step Electrodeposition

Electrodeposited crystalline Cu2Sb thin films are studied to evaluate the use of these electrodes as model systems for studying Cu2Sb as a lithium ion battery anode material. The films have been characterized with an emphasis on determining the film quality and relating the structure, composition, and morphology to the resulting electrochemical and morphological transformations that occur during electrochemical lithiation and delithiation. It is shown that electrodeposition can produce high quality films that are devoid of major defects and can be used to provide mechanistic insight on the electrochemistry of reversible lithium alloying. The CuxSb films show that the fundamental reaction mechanism remains largely unchanged for copper concentrations of 1>x>3. For the first time we show that the copper concentration greatly affects critical criteria for anode materials such as the initial coulombic efficiency and reversible capacity of the electrode material. Voltage limit experiments show that an overpotential is required to remove trapped lithium states. Additional ex-situ experiments reveal that internal strain created during the lithiation process is relieved by buckling, greatly altering the film surface area and geometry, and resulting in the formation of cracks upon delithiation. This process is only semi-reversible, and strained areas remain visible even when discharged outside the voltage window of Cu2Sb determined by differential capacity plots. The results presented here indicate that these electroplated thin films are useful as analytical tools for showing pathways to improving the performance and fundamental understanding of alloy based lithium-ion battery anodes.

Stress-corrosion cracking characterisation of the advanced aerospace Al–Li 2099-T86 alloy

New alloy developments driven by aircraft industry have identified aluminium lithium (Al–Li) alloys as potential candidates for substitution of incumbent high strength aluminium alloys used for manufacturing spacecraft and launchers. Whereas properties like specific stiffness, strength and toughness are proven as superior when compared to those of currently adopted Al alloys, the Stress Corrosion Cracking (SCC) characteristics are still an open aspect if advanced Al–Li alloys are considered for space structural applications. The present paper provides a comprehensive characterisation of the Al–Li 2099-T86 SCC performances.

Monitoring Volumetric Changes in Silicon Thin-Film Anodes through In Situ Optical Diffraction Microscopy.

A high-resolution in situ spectroelectrochemical optical diffraction experiment has been developed to understand the volume expansion/contraction process of amorphous silicon (a-Si) thin-film anodes. Electrodes consisting of 1D transmissive gratings of silicon have been produced through photolithographic methods. After glovebox assembly in a home-built Teflon cell, monitoring of the diffraction efficiency of these gratings during the lithiation/delithiation process is performed using an optical microscope equipped with a Bertrand lens. When the diffraction efficiency along with optical constants obtained from in situ spectroscopic ellipsometry is utilized, volume changes of the active materials can be deduced. Unlike transmission electron microscopy and atomic force microscopy characterization methods of observing silicon's volume expansion, this experiment allows for real-time monitoring of the volume change at charge/discharge cycles greater than just the first few along with an experimental environment that directly mimics that of a real battery. This technique shows promising results that provide needed insight into understanding the lithium alloying reaction and subsequent induced capacity fade during the cycling of alloying anodes in lithium-ion batteries.

A mechanism for shattering microexplosions and dispersive boiling phenomena in aluminum–lithium alloy based solid propellant

The microexplosive nature of multicomponent liquid fuels has been both studied and fielded to decrease droplet residence times and increase completeness of combustion. However, little work has focused on investigating microexplosive metal fuels to enhance the metal fuel combustion efficiency in traditional energetic material formulations. Microscopic surface videography was performed on two solid propellant formulations, one using aluminum (baseline) and the other with 80/20wt% Al–Li alloy as fuel additives. It was observed that the propellant combustion with neat aluminum formed large molten droplets at the surface as aluminum particles agglomerate, which is a well-known problem with aluminized propellants. In contrast, the Al–Li propellant formed an Al–Li melt-layer on the propellant surface during combustion. Droplets were ejected from the surface melt-layer through dispersive boiling. Above the surface, further dispersive boiling is observed from the ejected droplets and droplet-shattering microexplosions are also observed. These dynamics are thought to be a result of a large disparity in volatility (i.e., boiling points) between the metals in the molten alloy and the large Lewis number in the droplet, so that superheating occurs before the more volatile component (here Li) can diffuse to the surface. A Lewis number of 7440 was estimated for molten 80/20wt% Al–Li alloy, which is nearly three orders of magnitude larger than typical multicomponent liquid hydrocarbon droplets that microexplode, suggesting a higher propensity for molten droplet microexplosions. This would also indicate that a smaller amount of the volatile component might be necessary for microexplosions and dispersive boiling than observed for liquid hydrocarbon fuels. These dynamics are important for metal fuel applications, because injectors cannot be used to decrease droplet size in a metallized energetic material formulation.

Microstructure and mechanical properties of laser beam-welded AA2060 Al-Li alloy

Laser beam welding of a newly developed AA2060 aluminum–lithium (Al-Li) alloy was performed with AlSi12 filler wire. The fusion zone (FZ) consisted of dendritic solidification structure with the LiAlSi and CuAl2 phases and a small quantity of Mg2Si phase at the dendritic and grain boundaries, reducing the precipitation ability in the interior of grains. The microhardness was decreased in the FZ, being 90–120 HV0.1, compared to the based material (BM), being 152 HV0.1, and the variation was consistent with local strength across the joint. The joint transverse tensile strength was 416MPa and the elongation was 1.2%. The presence of grain boundary phases caused the fracture mode varied from a low–energy intergranular fracture in the FZ to a high–energy transgranular fracture in the BM. The formation of LiAlSi phases in the weld metal, resulting from the addition of Si, helped increase the tensile strength of the joints. The AA2060 Al-Li alloy is considered weldable due to the over 80% tensile strength of BM in laser beam welding, which readily meets most applications.

Microstructure Evolution of High Capacity Anode Electrode By in-Situ and in-Operando X-Ray Nano-CT

Alloy-typed materials have been studied as an anode active material to develop high energy density lithium ion batteries (LIBs). Especially, lithium alloys based on the group IV elements (Si, Ge, and Sn) are potential candidates for the anode material because of their high theoretical capacities and low operating voltages (1). Lithiation and delitiation of the anode alloys accompany large volume change that causes fractures, pulverizations, and delamination of the electrodes. The mechanical degradation reduces the reversible capacity and shortens the cycle life of the alloy anode LIBs. Particle fracture has been alleviated by nano-structuring the alloy-type anode materials due to the facile strain accommodation and the short diffusion path for electron and lithium ion transport in these nanostructured electrodes (2, 3). However, nano-structured particles have low tap density and lead to lower energy density anodes, making scale up difficult. The surface area of the material increases with decreasing particle size, which leads to large irreversible capacity loss due to the formation of the solid electrolyte interphase (SEI) (4). Klavetter et al. reported stable and high reversible capacity of a Ge0.9Se0.1alloy electrode with a common slurry coating method (5). They claimed that the inactive element (Se) alleviates the inevitable volume changes during the cell operation as Dahn et al. proposed (6). Currently, a fundamental understanding of the impact of a high capacity electrode’s microstructure change on LIB performance is still lacking due to the inhomogeneity, complexity, and three-dimensional (3D) nature of the electrode’s microstructure. In this study, a novel approach is proposed to gain greater understanding of the microstructure change of the alloy anode electrodes and its impact on the electrochemical performance. A special LIB cell was designed to monitor the microstructure change of high capacity anode electrodes with the synchrotron X-ray nano-CT technique at the Advanced Phothon Source of Argonne National Lab. The cell is composed of a quartz capillary housing and a wire-typed electrode to maximize X-ray penetration for the nano-CT scan (7). The structural evolution of the alloy electrodes is monitored to investigate crack propagations and pulverizations under in-operando 2D x-ray CT scan. Moreover, in-situ 3D x-ray CT scan enables to study the anisotropic volumetric changes at different voltage states. This simultaneous structural and electrochemical investigation of the alloy electrodes is an essential study to understand the fundamental degradation mechanism of high capacity lithium alloy anode. Acknowledgments: This work was supported by US National Science Foundation under Grant No. 1335850

Influence of thermomechanical treatments on localized corrosion susceptibility and propagation mechanism of AA2099 Al–Li alloy

In order to manifest the influence of specific microstructural component on the development of severe localized corrosion in an AA2099 aluminum–lithium alloy, the corrosion behavior of the alloy subjected to solution heat treatment, cold working and artificial ageing was investigated. Immersion testing and potentiodynamic polarization were employed to introduce localized corrosion; scanning electron microscopy and transmission electron microscopy were used to characterize the alloy microstructure and corrosion morphology. It was found that the susceptibility of the alloy to severe localized corrosion was sensitive to thermomechanical treatments. Additionally, the state of alloying elements influenced the mechanism of localized corrosion propagation. Specifically, the alloy in T8 conditions showed higher susceptibility to severe localized corrosion than that in other conditions. During potentiodynamic polarization, the alloy in solution heat-treated and T3 conditions displayed crystallographic corrosion morphology while the alloy in T6 and T8 conditions exhibited selective attack of grain interiors and grain boundaries in local regions.

Effect of adhesive quantity on failure behavior and mechanical properties of fiber metal laminates based on the aluminum–lithium alloy

The effect of adhesive quantity on the failure behavior and mechanical properties of fiber metal laminates based on the aluminum–lithium alloys (NFMLs) was investigated to optimize the manufacture process and further recognize the interface interaction. The NFMLs with different adhesive quantities (0g/m2, 20g/m2, 40g/m2, 60g/m2) were prepared primarily. Then, the influence of adhesive quantity on the interlaminar, tensile, flexural and fatigue properties of NFMLs was studied respectively. Also, the failure behaviors of NFMLs under different loading conditions were revealed. The results indicated that the adhesive layers significantly enhanced the interlaminar properties of the NFMLs within the investigated quantities. Moreover, the reasonable adhesive quantity also greatly improved the mechanical properties of the laminates, while an excessive amount deteriorated the performance. For the different properties, the peak values appeared under different adhesive quantities. Besides, the changing mechanical properties followed with the variation of failure mode. From the engineering perspective, the adhesive quantity of 40g/m2 is optimal to achieve the excellent performance of NFMLs.

Mechanical behavior and void coalescence analysis of cryorolled AA8090 alloy

Aluminum lithium alloy was rolled at two different temperatures, viz., 28 °C (301 K) and −196 °C (77 K). The thickness of the alloy was reduced by 75 % from its initial thickness (6 mm) in each condition. X-ray diffraction analysis was carried out on all samples to determine the grain size and dislocation density. The cryorolled sample exhibited a finer grain size with higher dislocation density, which was evidenced from micrographs obtained with transmission electron microscopy. Electron backscattered diffraction images revealed the presence of bimodal grain distribution in the rolled samples, in which the cryorolled sample exhibited a larger amount of ultrafine grains. Both tensile and hardness tests were performed on rolled samples. Cryorolled samples showed superior properties when comparing with room temperature rolled sample. Scanning electron microscopic images of fractured samples were used to analyze the void coalescence behavior. The various void coalescence parameters like void size, void area, length to width ratio of void, and ligament thickness were analyzed, and these results were correlated with microstructure, mechanical properties, crystallite size, and dislocation density in all conditions.

Diffusive transformation at high strain rate: On instantaneous dissolution of precipitates in aluminum alloy during adiabatic shear deformation

Abstract