Influence of Complexing Additives on the Reversible Deposition/Dissolution of Magnesium in an Ionic Liquid

Weber, Isabella; Ingenmey, Johannes; Schnaidt, Johannes; Kirchner, Barbara; Behm, R. Jürgen

doi:10.1002/celc.202001488

Cited by 11 publications

(32 citation statements)

References 83 publications

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“…Due to the low solubility of magnesium hydroxide, the outer layer of deposition will undergo dissolution periodically, which makes it unstable, producing unstable voltage fluctuation 56 . The low solubility Mg(OH) 2 can be related to its standard Gibbs free energy,

{ΔG}_{f}^{θ}

(−833.7 kJ mol −1 ) where it establishes a high energy barrier which makes it difficult to dissolve in aqueous solution and has become the big hurdle to irreversible Mg electrode in rechargeable MAFC development to date as the study on reversibility of Mg is scanty 36,149 . Currently, the work on electrocatalyst material improvement is centered on addressing the sluggish oxygen reduction reaction at cathode such as the porous perovskites 150 and others, 151 developing a novel electrocatalyst that function to oxidize Mg(OH) 2 layer is worthy to be paid attention to.…”

Section: Current Challenges and Approachesmentioning

confidence: 99%

Critical review on development of magnesium alloy as anode inMg‐Airfuel cell and additives in electrolyte

et al. 2021

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Summary This study aimed to provide a critical review of the magnesium‐air fuel cell (MAFC) system to provide readers with an overall comprehension of MAFC, which focuses on the modification of the magnesium anode and properties of saltwater as an electrolyte. Although MAFC is benign to the environment, it is well‐known for its challenging corrosion issue and by‐product deposition that affect its durability for commercialization and long‐term application. Since that MAFC is able to use seawater as electrolyte, it has great potential to be used as an alternative energy option for the marine sector. This journal will dissect the ability of MAFC to be used as a competitive alternative energy. Over the years, researchers have adopted several approaches, such as experimenting with different types of magnesium alloy and anode fabrication techniques, to tackle corrosion problems to alter the microstructure and mechanical properties of the anode in addition to applying a coating protection and using Mg‐based composite material. Furthermore, studies intriguingly and gradually focused on electrolyte formulation with different types of additives to address the debilitating precipitation issue and improve the discharge performance. Given the problems that arise in the system, currently, MAFC commercial products are only suitable as emergency back‐up power. In future work, an improved storage system for MAFC should be built to accommodate the precipitation products while maintaining the desired cell performance.

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{ΔG}_{f}^{θ}

Section: Current Challenges and Approachesmentioning

confidence: 99%

Critical review on development of magnesium alloy as anode inMg‐Airfuel cell and additives in electrolyte

et al. 2021

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“…This may create a severe obstacle in the RTIL environment due to the high concentration of counter ions. Indeed, reductive decomposition of the TFSI − anion in the presence of Mg had been identified in several studies and proposed as a major reason for the observed passivation of the electrode for reversible Mg deposition/stripping or O 2 reduction/evolution [10,11,15,25–27] . This was attributed to Mg 2+ complex formation, where TFSI anions are coordinated to Mg 2+ , [28,29] and decomposition of TFSI − upon reduction of the Mg 2+ central ion to Mg + .…”

Section: Introductionmentioning

confidence: 98%

“…Recently we started a systematic study on the deposition/stripping of Mg and the reduction/evolution of O 2 from/in a room temperature ionic liquid (RTIL), specifically in 1‐butyl‐1‐ methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMP‐TFSI), [10–15] which will be continued in the present study. RTILs are attractive candidates as solvent in Li and post‐Li ion batteries because of their wide electrochemical stability window, low flammability and low vapor pressure, [16–18] where the latter is especially important for metal‐air batteries [19–24] .…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Aspects and Side Reactions during Reversible Mg Deposition and Oxygen Reduction on a Pt Film Electrode in BMP‐TFSI‐Based Electrolytes: A DEMS Study

Jusys

Behm

2023

ChemElectroChem

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Reversible Mg deposition/stripping and O 2 reduction/evolution on a Pt film electrode in neat and O 2 -saturated 1-butyl-1methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMP-TFSI) electrolytes, containing Mg(TFSI) 2 and/or Mg(BH 4 ) 2 as Mg source as well as Mg(BH 4 ) 2 and/or the crown ether 18-c-6 as additive, were investigated by online differential electrochemical mass spectrometry (DEMS) and by scanning electron microscopy/energy dispersed X-ray spectroscopy. Combined cyclic voltammetry and DEMS measurements reveal a complex network of partial reactions, including borohydride electrooxidation by reaction with water or O 2 , chemical bulk reaction of these components, as well as electro-oxidation of H 2 , and electrolyte decomposition, in addition to the primary reactions Mg deposition/stripping and ORR/OER. They provide detailed insights into the potential dependent reactions occurring under these conditions, demonstrating that also the additive 18-c-6 undergoes decomposition upon reduction of Mg 2 + . Contributions from chemical bulk reactions are resolved by DEMS measurements in borohydride containing solution without a Pt electrode. Electrocatalytic borohydride oxidation, explored by similar measurements with a Pt electrode, can lead to H 2 or H + formation. Under open circuit potential conditions, charge compensation by the ORR results in the formation of a mixed potential. Consequences of these findings for applications in Mg-air batteries are discussed.

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“…Merely, a handful of studies reported the electrochemically induced passivation film formation at the Mg electrolyte/electrode interface and its microscopic nature. ,− Involvement of the adsorption–desorption processes and formation of the complexes at the interface during Mg deposition–dissolution are extremely complicated and difficult to be studied simply by cyclic voltammetry and ex situ analysis methods. ,− The lack of adequate in situ techniques is a major roadblock preventing us from understanding the interfacial processes in Mg electrolytes, which are crucial to the development of a practical rechargeable Mg system. Thus, it is critical to provide an in-depth analysis of the interfacial evolution at the Mg metal anode.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the Dynamic Solid Electrolyte Interphase in Mg Electrolytes for Rechargeable Mg-Ion Batteries

Fan

Cora

2022

ACS Appl. Mater. Interfaces

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Formation and evolution of the microscopic solid electrolyte interphase (SEI) at the Mg electrolyte/electrode interface are less reported and need to be completely understood to overcome the compatibility challenges at the Mg anode–electrolyte. In this paper, SEI evolution at the Mg electrolyte/electrode interface is investigated via an in situ electrochemical quartz crystal microbalance with dissipation mode (EQCM-D), electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectrometry (FTIR). Results reveal remarkably different interfacial evolutions for the two Mg electrolyte systems that are studied, a non-halogen Mg(TFSI)2 electrolyte in THF with DMA as a cosolvent (nhMg-DMA electrolyte) versus a halogen-containing all-phenyl complex (APC) electrolyte. The nhMg-DMA electrolyte reports a minuscule SEI formation along with a significant Coulomb loss at the initial electrochemical cycles owing to an electrolyte reconstruction process. Interestingly, a more complicated SEI growth is observed at the later electrochemical cycles accompanied by an improved reversible Mg deposition attributed to the newly formed coordination environment with Mg2+ and ultimately leads to a more homogeneous morphology for the electrochemically deposited Mg0, which maintains a MgF2-rich interface. In contrast, the APC electrolyte shows an extensive SEI formation at its initial electrochemical cycles, followed by a SEI dissolution process upon electrochemical cycling accompanied by an improved coulombic efficiency with trace water and chloride species removed. Therefore, it leads to SEI stabilization progression upon further electrochemical cycling, resulting in elevated charge transport kinetics and superior purity of the electrochemically deposited Mg0. These outstanding findings augment the understanding of the SEI formation and evolution on the Mg interface and pave a way for a future Mg-ion battery design.

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Influence of Complexing Additives on the Reversible Deposition/Dissolution of Magnesium in an Ionic Liquid

Cited by 11 publications

References 83 publications

Critical review on development of magnesium alloy as anode inMg‐Airfuel cell and additives in electrolyte

Critical review on development of magnesium alloy as anode inMg‐Airfuel cell and additives in electrolyte

Mechanistic Aspects and Side Reactions during Reversible Mg Deposition and Oxygen Reduction on a Pt Film Electrode in BMP‐TFSI‐Based Electrolytes: A DEMS Study

Evolution of the Dynamic Solid Electrolyte Interphase in Mg Electrolytes for Rechargeable Mg-Ion Batteries

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