Understanding the initial stages of reversible Mg deposition and stripping in inorganic nonaqueous electrolytes

Journal Article · Wed Apr 08 00:00:00 EDT 2015 · Chemistry of Materials

DOI:https://doi.org/10.1021/acs.chemmater.5b00389· OSTI ID:1235269

Canepa, Pieremanuele ^[1]; Gautam, Gopalakrishnan Sai ^[1]; Malik, Rahul ^[1]; Jayaraman, Saivenkataraman ^[1]; Rong, Ziqin ^[1]; Zavadil, Kevin R. ^[2]; Persson, Kristin ^[3]; Ceder, Gerbrand ^[2]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Multivalent (MV) battery architectures based on pairing a Mg metal anode with a high-voltage (~3 V) intercalation cathode offer a realistic design pathway toward significantly surpassing the energy storage performance of traditional Li-ion-based batteries, but there are currently only few electrolyte systems that support reversible Mg deposition. Using both static first-principles calculations and ab initio molecular dynamics, we perform a comprehensive adsorption study of several salt and solvent species at the interface of Mg metal with an electrolyte of Mg²⁺ and Cl–dissolved in liquid tetrahydrofuran (THF). Our findings not only provide a picture of the stable species at the interface but also explain how this system can support reversible Mg deposition, and as such, we provide insights in how to design other electrolytes for Mg plating and stripping. Furthermore, the active depositing species are identified to be (MgCl)⁺ monomers coordinated by THF, which exhibit preferential adsorption on Mg compared to possible passivating species (such as THF solvent or neutral MgCl₂ complexes). We found that upon deposition, the energy to desolvate these adsorbed complexes and facilitate charge transfer is shown to be small (~61–46.2 kJ mol^–1 to remove three THF from the strongest adsorbing complex), and the stable orientations of the adsorbed but desolvated (MgCl)⁺ complexes appear to be favorable for charge transfer. Lastly, observations of Mg–Cl dissociation at the Mg surface at very low THF coordinations (0 and 1) suggest that deleterious Cl incorporation in the anode may occur upon plating. In the stripping process, this is beneficial by further facilitating the Mg removal reaction.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1235269
• Report Number(s): SAND-2015-4342J; 590458
• Journal Information: Chemistry of Materials, Vol. 27, Issue 9; ISSN 0897-4756
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
25 ENERGY STORAGE