Lithium Dendrite Suppression Via Alkali and Alkaline Earth Cation Additives (original) (raw)
Related papers
Direct observation of lithium metal dendrites with ceramic solid electrolyte
Scientific Reports
Dendrite formation, which could cause a battery short circuit, occurs in batteries that contain lithium metal anodes. In order to suppress dendrite growth, the use of electrolytes with a high shear modulus is suggested as an ionic conductive separator in batteries. One promising candidate for this application is Li7La3Zr2O12 (LLZO) because it has excellent mechanical properties and chemical stability. In this work, in situ scanning electron microscopy (SEM) technique was employed to monitor the interface behavior between lithium metal and LLZO electrolyte during cycling with pressure. Using the obtained SEM images, videos were created that show the inhomogeneous dissolution and deposition of lithium, which induce dendrite growth. The energy dispersive spectroscopy analyses of dendrites indicate the presence of Li, C, and O elements. Moreover, the cross-section mapping comparison of the LLZO shows the inhomogeneous distribution of La, Zr, and C after cycling that was caused by lithiu...
arXiv: Applied Physics, 2020
All solid state Li-ion batteries employing metallic lithium as an anode offer higher energy densities while also being safer than conventional liquid electrolyte based Li-ion batteries. However, the growth of tiny filaments of lithium (dendrites) across the solid state electrolyte layer leads to premature shorting of cells and limits their practical viability. The microscopic mechanisms that lead to lithium dendrite growth in solid state cells are still unclear. Using garnet based lithium ion conductor as a model solid state electrolyte, we show that interfacial void growth during lithium dissolution precedes dendrite nucleation and growth. Using a simple electrostatic model, we show that current density at the edges of the voids could be amplified by as much as four orders of magnitude making the cells highly susceptible to dendrite growth after void formation. We propose the use of metallic interlayers with low solubility and high nucleation overpotential for lithium to delay void...
Effect of Charge Transfer Resistance on Morphology of Lithium Electrodeposited in Ionic Liquid
Journal of The Electrochemical Society, 2016
Secondary batteries based on lithium (Li) metal anodes are a potential candidate for next-generation energy storage devices, but their practical commercialization has so far been greatly limited by safety issues and cycle-life limitations associated with the formation of Li dendrites. This study therefore looks at the morphology of Li that is electrodeposited in room-temperature ionic liquids (RTILs) with a view to determining the most suitable electrolyte properties. Particular focus is given to how the distribution of nucleation points changes in relation to the charge transfer resistance of the RTIL, which is varied by changing the viscosity of the electrolyte. Through this, it is found that a more viscous electrolyte with a higher charge transfer resistance produces Li deposits that are more evenly distributed and smaller in size.
Journal of The Electrochemical Society, 2014
The morphology of electrodeposited lithium in room-temperature ionic liquids was investigated by ex situ SEM observations, and the dependence of the distribution of the electrodeposited lithium nuclei on current density was discussed with respect to the lithium-ion diffusion coefficient. It was concluded that the deposits are better distributed with a decreased size when the current density is increased in the current range where the deposition is charge-transfer controlled. Under a larger current density at which the deposition is diffusion controlled, larger dendritic deposits are observed, although deposits are well distributed over a large area. Under so large current density that the diffusion of lithium ions is slower than the lithium ion reduction, the electrode potential becomes highly negative. Abovementioned tendency is very common for the electrodeposition of noble metals from an aqueous solution, but it was firstly presented for lithium metal. It is probably due to very low reactivity of the ionic liquid used with lithium in this study.
Effect of an organic additive in the electrolyte on suppressing the growth of Li dendrites in Li metal-based batteries, 2018
Lithium metal has attracted much attention as an anode material for high-performance batteries owing to its high specific capacity and electrode potential. However, the Li metal electrode could suffer from the dendritic growth of Li during the cell operation due to the high reactivity of Li with organic electrolytes. To address this issue, we propose the use of thiourea as an electrolyte additive for Li metal-based batteries. The thiourea additive in LiTFSI/TEGDME electrolyte allowed the formation of a stable and uniform solid electrolyte interface layer on the Li electrode, thereby aiding the suppression of dendritic growth of Li and further electrolyte decomposition. Accordingly, a Li symmetric cell containing the thiourea additive exhibited six-times longer cycle life than a cell without the additive. Further, the electrolyte additive was also successfully employed in a Li-O 2 cell to improve its cyclability.
Homogeneous Lithium Electrodeposition with Pyrrolidinium-Based Ionic Liquid Electrolytes
ACS Applied Materials & Interfaces, 2015
In this study, we report on the electroplating and stripping of lithium in two ionic liquid (IL) based electrolytes, namely N-butyl-N-methylpyrrolidinium bis-(fluorosulfonyl) imide (Pyr 14 FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr 14 TFSI), and mixtures thereof, both on nickel and lithium electrodes. An improved method to evaluate the Li cycling efficiency confirmed that homogeneous electroplating (and stripping) of Li is possible with TFSI-based ILs. Moreover, the presence of native surface features on lithium, directly observable via scanning electron microscope imaging, was used to demonstrate the enhanced electrolyte interphase (SEI)-forming ability, that is, fast cathodic reactivity of this class of electrolytes and the suppressed dendrite growth. Finally, the induced inhomogeneous deposition enabled us to witness the SEI cracking and revealed previously unreported bundled Li fibers below the pre-existing SEI and nonrod-shaped protuberances resulting from Li extrusion.
Energy Materials, 2022
With the fullness of time, metallic lithium (Li) as an anode could become highly promising for high-energy-density batteries. Theoretically, using Li metal as the negative electrode can result in higher theoretical capacity and lower oxidation voltage and density than in current commercially available batteries. During the charge/discharge process, however, metallic Li shows unavoidable drawbacks, such as dendritic growth, causing capacity degradation and a solid electrolyte interphase (SEI) layer derived from the side reactions between the Li metal anode and the electrolyte, resulting in depletion of the electrolyte. The formation of a suitable SEI is crucial to avoid the side reactions at the interface by circumventing direct contact. Unavoidable dendritic growth at the Li metal anode can be controlled by its ionic conductivity. Furthermore, the SEI is also required as a mechanical reinforcement for withstanding the volume change and suppressing dendritic growth in the Li metal anode. A limiting factor due to complex SEI formation must be considered from the perspectives of chemical and mechanical properties. To further enhance the cycling performance of Li metal batteries, an in-depth understanding of the SEI needs to be achieved to clarify these issues. In this mini review, we focus on the SEI, which consists of various deposited components, and discuss its ionic conductivity and mechanical strength for applications in electric vehicles.
Electrochemistry, 2012
The behavior of lithium (Li) electrodeposition in room temperature ionic liquids (RTILs) containing aliphatic quaternary ammonium cation was investigated by in-situ optical microscope observation. As a result, round shape Li deposits were obtained after deposition in all cases with vinylene carbonate (VC) as an additive, while most deposits were dendritic without VC. AC impedance spectroscopic measurements indicated that the dendrite growth was suppressed when a surface film with large resistance was generated. The dendrite suppression effect by VC addition was confirmed in the Py14[TFSA]-based and TMHA[TFSA]-based electrolytes as well as in the PP13[TFSA]based electrolyte.
Design principles for electrolytes and interfaces for stable lithium-metal batteries
Nature Energy, 2016
A lithium-metal battery (LMB) consists of three components: a Li-metal anode, a Li-ion-conducting electrolyte separator, and a cathode 1. Recharging a LMB requires electrodeposition of lithium on to itself, a process that is fundamentally unstable. At low current densities, concentration of electric field lines and preferential transport of ions to rough regions on the electrode surface produce the morphological instability loosely termed dendrites. Meanwhile, at high current densities, depletion of anions in the electrolyte near the anode creates a space charge that drives a hydrodynamic instability termed electroconvection 2. This electroconvection draws ions away from regions surrounding a growing dendrite and focuses them on the dendrite tip, enhancing dendrite growth. Thus, for quite fundamental physical reasons, recharge of a LMB at either low or high currents produces rough and dendritic deposition of the metal. Reactivity of Li with aprotic liquid electrolytes forms a porous, ion-conducting solid electrolyte interphase (SEI) layer on the metal 3 (stage I in Fig. 1). A uniform and stable SEI can passivate the Li surface, preventing further reaction, but spontaneously formed SEIs on Li are typically inhomogeneous and mechanically fragile (stage II in Fig. 1). An inhomogeneous SEI destabilizes LMBs by providing nucleation sites for dendrite formation at any current density, while a fragile SEI may crack or delaminate during battery cycling, exposing fresh Li to the electrolyte each cycle, which ultimately depletes the electrolyte. Because the two processes (dendrite formation and electrolyte loss) occur in tandem, it is a formidable challenge to create a LMB that operates stably for an extended time. This Perspective surveys approaches for designing batteries based on Li-metal anodes that do not fail via dendrite-induced short circuits. We specifically focus on rational strategies based on regulating charge transport and Li reactivity at interfaces for stabilizing the Li-metal anode. It is shown that a universal state diagram can be created, in which knowledge of material parameters and cell operating conditions can be used to provide explicit guidance about the electrolyte separator and interface designs for stable LMB operation. The Perspective also highlights recent successes and discusses