An Overview on Protecting Metal Anodes with Alloy‐Type Coating

Abstract

The current revival of lithium metal batteries (LMB) has been driven by both the search for high energy‐density systems and the development of solid‐state batteries. Lithium electrode surface engineering is crucial to limit both the dendritic growth and the electrolyte reduction. Among the various strategies to obtain protecting layers, there has been a recent growing interest in metal coatings forming alloys with lithium. Here, various strategies to coat lithium and other metal electrodes (sodium, potassium and magnesium) are reviewed and discussed with respect to their efficiency, versatility, and their possible practical transfer to the battery industry.

Alloying electrode coatings towards better magnesium batteries

“…In the literature, the charge transfer and the plating mechanism processes occurring on the surface of these coated electrodes are not yet fully understood. 16 The presence of insulating by-products (mainly chlorides) in the composite layers was proposed to create a potential gradient, further enabling the ionic diffusion across the coating and leading to plating occurring below the coating layer, further denoted as plating underneath. 12 Moreover, the existence of chloride species dissolved in the electrolyte has been suggested to prevent further passivation through the formation of surface adsorbed species.…”

“…The as-protected electrodes exhibit enhanced electrochemical performance, mainly induced by the minimised dendritic growth during plating. 16 Although magnesium dendrites are not unexpected, [17][18][19] similar protocols were thus applied to magnesium electrodes with the objective of using more conventional electrolytes. For example, in contact with a SnCl 2 or BiCl 3 solution, a composite layer containing the Mg 2 Sn or Mg 3 Bi 2 alloy covers the magnesium electrode surface and enables fast ion transport.…”

Importance of Halide Ions in the Stabilization of Hybrid Sn-Based Coatings for Lithium Electrodes

“…26−29 For the latter, various coating techniques have already been presented to protect the Li-metal surface and allow the delay of electrode instabilities, such as atomic layer deposition (ALD), spin coating, or direct chemical reaction between a solution and the electrode. 27,30 In this study, we focus on protective layers made by the spontaneous reduction of a metal or semimetal in contact with lithium to form an intermetallic compound. Nazar's team was the first to propose such a coating by immersing the Li metal in an MCl x /THF solution (M = In, Zn, Bi, and As) to obtain a hybrid layer composed of Li y M and LiCl as revealed by X-ray diffraction (XRD).…”

Towards understanding the nucleation and growth mechanism of Li dendrites on zinc oxide-coated nickel electrodes

“…A major technical problem associated with Li metal anodes, however, is the growth of dendrites, which leads to the formation of inactive Li during the plating and stripping process, resulting in poor cycle life, low coulombic efficiency (CE) as well as battery safety concerns [4][5][6] . To tackle the dendrite formation issue, researchers have proposed a wide range of solutions and strategies, from the use of various electrode designs and composite anodes to electrolyte engineering and interface modification, often including theoretical simulation methods [7][8][9][10] . One promising approach that has recently gained attention is the use of three-dimensional (3D) host structures to contain the Li metal anodes 11 .…”

“…[4][5][6] To tackle the dendrite formation issue, researchers have proposed a wide range of solutions and strategies, from the use of various electrode designs and composite anodes to electrolyte engineering and interface modication, oen including theoretical simulation methods. [7][8][9][10] One promising approach that has recently gained attention is the use of threedimensional (3D) host structures to contain the Li metal anodes. 11 The high surface area of 3D structures can help delay the systematic build-up of dendrites observed in host-less Li metal anodes, 12,13 by dissipating the local current density and regulating the important volume changes.…”