Coordination-Dependent Chemical Reactivity of TFSI Anions at a Mg Metal Interface
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- Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Charge transfer across the electrode–electrolyte interface is a highly complex and convoluted process involving diverse solvated species with varying structures and compositions. Despite recent advances in in situ and operando interfacial analysis, molecular specific reactivity of solvated species is inaccessible due to a lack of precise control over the interfacial constituents and/or an unclear understanding of their spectroscopic fingerprints. However, such molecular-specific understanding is critical to the rational design of energy-efficient solid–electrolyte interphase layers. We have employed ion soft landing, a versatile and highly controlled method, to prepare well-defined interfaces assembled with selected ions, either as solvated species or as bare ions, with distinguishing molecular precision. Equipped with precise control over interfacial composition, we employed in situ multimodal spectroscopic characterization to unravel the molecular specific reactivity of Mg solvated species comprising (i.e., bis(trifluoromethanesulfonyl)imide, TFSI–) anions and solvent molecules (i.e., dimethoxyethane, DME/G1) on a Mg metal surface relevant to multivalent Mg batteries. In situ multimodal spectroscopic characterization revealed higher reactivity of the undercoordinated solvated species [Mg-TFSI-G1]+ compared to the fully coordinated [Mg-TFSI-(G1)2]+ species or even the bare TFSI–. These results were corroborated by the computed reaction pathways and energy barriers for decomposition of the TFSI– within Mg solvated species relative to bare TFSI–. Finally, we evaluated the TFSI reactivity under electrochemical conditions using Mg(TFSI)2–DME-based phase-separated electrolytes representing different solvated constituents. Based on our multimodal study, we report a detailed understanding of TFSI– decomposition processes as part of coordinated solvated species at a Mg-metal anode that will aid the rational design of improved sustainable electrochemical energy technologies.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Argonne National Laboratory (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Environmental Measurements Laboratory (EML), New York, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC05-76RL01830; AC06-76RLO; AC02-05CH11231; AC02-06CH11357; AC06-76RLO1830
- OSTI ID:
- 1958189
- Alternate ID(s):
- OSTI ID: 2339564
- Report Number(s):
- PNNL-SA-178429
- Journal Information:
- ACS Applied Materials and Interfaces, Vol. 15, Issue 5; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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