Mixed Organic/Ionic Liquid Electrolytes Compatible with Forcespun Carbon Microfiber Electrodes in Lithium Ion Batteries

Abstract

We present results on the Forcespinning (FS) of PVP solution precursors for the mass production of porous carbon microfibers as anode materials for Lithium-ion batteries. The porous microfiber carbon anodes are produced using a scalable technique (FS) and subsequent thermal treatment (carbonization). The carbon fiber anodes were porous and flexible. The flexible microfibers were directly used as working electrode in lithium-ion batteries without a current collector, conducting additives, or binder. Mixed organic/ionic liquid electrolytes (MOILEs) were employed in Lithium ion cell cycling studies with the porous carbon anode and commercial cathodes to investigate the electrochemical and cycling performance of the Li-ion cells. A temperature range of 25 to 60 °C and different current rates were used to study the effects of temperature on the ionic conductivity of MOILEs and on the electrochemical performance of LIB cells. 1-Ethyl-3-Methyl-imidazolium Lithium bis(trifluoromethanesulfonyl) imide (EMI-TFSI) ionic liquid was synthesized in our laboratory by reacting the EMI cation and TFSI ion in a 1:1 mole ratio. The EMI-TFSI ionic liquid and LiTFSI salt were mixed with organic liquids (Ethylene carbonate (EC) dimethyl carbonate (DMC) and Succinonitril (SCN) to improve the ionic transport of the electrolyte during the charge/discharge cycles. The carbon microfiber electrodes delivered a good electrochemical performance and Coulombic efficiency when used half and full cells. This study provides a novel and feasible pathway for designing and developing promising anodes with mixed organic/ionic liquid electrolytes for high-performance lithium ion batteries.