Electrolytic Solvation Effects in Fluoroethylene Carbonate and Trifluoropropylene Carbonate: A Comparative Study Based
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https://doi.org/10.1007/s11664-020-08601-0 Ó 2020 The Minerals, Metals & Materials Society
ASIAN CONSORTIUM ACCMS–INTERNATIONAL CONFERENCE ICMG 2020
Electrolytic Solvation Effects in Fluoroethylene Carbonate and Trifluoropropylene Carbonate: A Comparative Study Based on First-Principles Calculation ANOOP KUMAR KUSHWAHA ,1,2 SUSHRI SOUMYA JENA,1 MIHIR RANJAN SAHOO,1 and SAROJ KUMAR NAYAK1 1.—School of Basic Sciences, Indian Institute Bhubaneswar 752050, India. 2.—e-mail: [email protected]
of
Technology
Bhubaneswar,
Owing to its high energy density, high specific capacity, and low self-discharge rate, the Li-ion battery (LIB) has been implemented in a wide area of applications starting from small electronic devices to large electric vehicles. However, the use of LIBs in electric vehicles has not yet been commercialized on a large scale due to the unavailability of suitable electrolytic solvents for highvoltage LIBs. Recently, fluorinated carbonates have gained much attention as potential high-voltage electrolytes for having desirable physical properties such as low melting points, low flammability, and high electrochemical stability. However, the solvation properties of Li+ in electrolytic fluorinated carbonates solvents require detailed investigations. With the first-principles calculations, the present work provides a comparative study of the structural, electronic, thermochemical and solvation properties of Li+ solvated by fluoroethylene carbonate (FEC), trifluoropropylene carbonate (TFPC), i.e., Li+(FEC)n and Li+-(TFPC)n, where n = 1–4. We have found that the structural properties, e.g., bond length C=O (of carbonyl) and associated infrared (IR) frequency, show similar variation for both the fluorinated Li-carbonate complexes. However, higher solvation energy and lower desolvation energy for the TFPC than the FEC show the opposite nature of their respective pristine carbonate counterparts. Our result, i.e., superior solvation energy of TFPC compared to FEC, is in good agreement with the experimentally developed solvating power series. Based on the solvation/desolvation energy, we conclude that TFPC could be a better high-voltage electrolyte for LIBs. Key words: Electrolytic solvent, fluoroethylene carbonate, trifluoropropylene carbonate, solvation shell
INTRODUCTION Unlike other rechargeable batteries, Li-ion batteries (LIBs) show specific characteristics such as high energy density (250–693 Wh/L), high specific capacity (100–265 Wh/kg), high power density (250– 340 W/kg), low self-discharge rate ( 0.35–2.5% per
(Received May 13, 2020; accepted November 3, 2020)
month), excellent charge–discharge rate (80–90%), and long cycle durability (400–1200 cycles).1–4 Due to the characteristics mentioned above, LIBs have been implemented in a wide range of applications starting from miniature electronic devices to large electric vehicles. However, the use of LIBs in electric vehicles has not yet been commercialized due to the unavailability of efficient electrode materials and electrolytic solvents for high-volta
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