The Use of Mixed Organic/Ionic Liquid Electrolytes with Forcespun Metal Oxides/Carbon Microfiber Electrodes in Lithium Ion Batteries

Abstract

We present results on the Forcespinning (FS) of PAN solution precursors for the mass production of metal/oxides carbon (MO/C) composite microfibers as anode materials for Lithium-ion batteries. The MO/C composite microfiber anodes are produced using a scalable technique (FS) and subsequent thermal treatment (calcination). The composite anodes were porous and flexible. The flexible composite microfibers were directly used as binder free electrodes in lithium-ion batteries. Mixed organic/ionic liquid electrolytes (MOILEs) were employed in Lithium ion cell cycling studies with the MO/C composite fibers and composite fiber cathodes to investigate the electrochemical and cycling performance of the Li-ion cells. The ionic conductivity of MOILEs and the electrochemical performance of LIB cells were investigated at different temperatures and current rates. 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 (SN) to improve the ionic transport of the electrolyte during the charge/discharge cycles. The MO/C composite electrodes delivered a good electrochemical performance and Columbic efficiency when used as half and full cells. The electrochemical performance of the Forcespun composite fiber cathodes was also investigated in half-cell cycling.