Synthesis and electrochemical studies of novel ionic liquid based electrolytes

Author

Avinash Raju Vadapalli

Keywords and Phrases

Imidazolium; Ionic Liquids; Lithium batteries; Pyrrolidinium

Abstract

"Room temperature ionic liquids (RTILs) have received substantial interest as nonaqueous electrolytes in lithium ion- and metal-air batteries in recent years due to their low volatility, non-flammability, wide liquid range, and thermal stability characteristics. Towards developing a new generation of high specific energy lithium ion batteries, a series of imidazolium and pyrrolidinium based ionic liquids were synthesized and explored as nonaqueous electrolytes in lithium-, lithium ion-, and lithium-air batteries. Pyrrolidinium-TFSI based ionic liquids have wide electrochemical stability (5.7 - 6.2 V vs Li/Li⁺); however, they show limited thermal stabilities and lithium cell discharge characteristics. TFSI-based ionic liquids are thermally and electrochemically more stable when compared with their BF₄-based analogues. A series of fluorinated ionic liquid electrolytes were synthesized and investigated for their use in lithium-air batteries. These ionic liquids have improved the diffusion coefficient and higher solubility of oxygen when compared with currently used nonaqueous electrolytes.

Cathode materials, such as LiNi_1/3Mn_1/3Co_1/3O₂ and LiFePO₄, were chemically delithiated using nitronium tetrafluoroborate (NO₂BF₄), or disodium peroxydisulfate (Na₂S₂O₈>), to explore their effect on the oxidative degradation of the carbonate based electrolytes. Using fluoroethylene carbonate as the electrolyte additive, electrolyte degradation was monitored by ¹⁹F NMR spectroscopy. Formation of the solid electrolyte interface (SEI) on the delithiated cathode materials was probed using surface techniques, such as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM)"--Abstract, page iii.

Advisor(s)

Reddy, Prakash

Committee Member(s)

Leventis, Nicholas
Winiarz, Jeffrey G.
Nam, Paul Ki-souk
Chandrashekhara, K.

Department(s)

Chemistry

Degree Name

Ph. D. in Chemistry

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2015

Pagination

xi, 126 pages

Note about bibliography

Includes bibliographic references (pages 111-125).

Rights

© 2015 Avinash Raju Vadapalli, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Ionic solutions
Lithium cells
Electrochemistry

Thesis Number

T 10837

Electronic OCLC #

936209482

Recommended Citation

Vadapalli, Avinash Raju, "Synthesis and electrochemical studies of novel ionic liquid based electrolytes" (2015). Doctoral Dissertations. 2460.
https://scholarsmine.mst.edu/doctoral_dissertations/2460