Reversible Electrochemical Interface of Mg Metal and a Conventional Electrolyte Enabled by Intermediate Adsorption

New and important roles for Mg cation clusters at electrified interfaces are revealed by operando soft x-ray absorption spectroscopy (XAS), electrochemical impedance spectroscopy (EIS), and distribution of relaxation times (DRT) analysis.

Scientific Achievement

A detailed description of the complex charge-transfer process at a Mg/electrolyte interface is provided where an additional adsorption process, during Mg plating, is confirmed to be a key step.

Significance and Impact

This study demonstrates a comprehensive approach to probing and understanding electrified electrode/electrolyte interfaces where the discovery and understanding of new adsorption chemistries are critical for the predictive design of a reversible interface.

Research Details

  • A critical adsorption step between Mg0 atoms and active Mg cation clusters involving BH4− anions is identified to be the key enabler for reversible Mg plating/stripping.
  • Addition of BH4− leads to the neutralization of the first solvation shell of Mg cationic clusters between Mg2+ and TFSI- and enhanced reductive stability of free TFSI-.
  • A new interpretation method (see Figure), deconvoluting operando EIS data, is demonstrated to be a novel and feasible approach to probe and understand the electrified interface, especially when coupled with operando soft XAS experiments.

Download this highlight 

DOI:  10.1021/acsenergylett.9b02211

Latest Updates

See All
  • A Message from JCESR Director George Crabtree

    Despite the coronavirus challenges, JCESR continues to push the frontier of energy storage science as we telecommute from home, like much of the nation. We are turning our attention to computation, data analysis and paper writing which continues at a normal or higher pace, enabled … Read More

  • You’re invited: Idaho National Laboratory and JCESR webinar on energy storage (March 18 )

    Electrification is changing the energy landscape of the Mountain West region. While energy storage remains a key enabler to this transformation, infrastructure upgrade and supply chain development will be a key driver for this new economy. Join us on March 18 for a webinar where we’ll … Read More

  • Direct Nano-Synthesis Methods Notably Benefit Mg-Battery Cathode Performance

    A novel Mg cathode material – CuCo2S4 – was identified as a conversion material where direct nano-synthesis was required to provide the best electrochemical performance and deliver 350 mAh·g-1 at 60 °C, a capacity nearly double that of ball-milled material with similar dimensions. Read More

  • Quantifying Capacity Losses due to Solid Electrolyte Interphase Evolution

    We quantified the capacity loss originating in solid electrolyte interphase (SEI) growth during each cycle and extracted the proportionality constant for SEI growth following a parabolic growth law. This continuous SEI growth contributes to the increasing overpotential, leading to capacity fading at a given constant … Read More

  • On Lifetime and Cost of Redox-Active Organics for Aqueous Flow Batteries

    In this viewpoint, we recommend methodology for (1) testing aqueous organic flow batteries to better understand the fade mechanisms and failure modes, and for (2) techno-economic assessment of these batteries that incorporates the costs associated with electrolyte decay and replacement to articulate a feasible design … Read More