A Long-Life Lithium Ion Battery with Enhanced Electrode/Electrolyte Interface by Using an Ionic Liquid Solution

Abstract

In this paper, we report an advanced long-life lithium ion battery, employing a Pyr(14)TFSI-LiTFSI non-flammable ionic liquid (IL) electrolyte, a nanostructured tin carbon (SnC) nanocomposite anode, and a layered LiNi1/3Co1/3Mn1/3O2 (NMC) cathode. The IL-based electrolyte is characterized in terms of conductivity and viscosity at various temperatures, revealing a Vogel-Tammann-Fulcher (VTF) trend. Lithium half-cells employing the Sn-C anode and NMC cathode in the Pyr(14)TFSI-LiTFSI electrolyte are investigated by galvanostatic cycling at various temperatures, demonstrating the full compatibility of the electrolyte with the selected electrode materials. The NMC and Sn-C electrodes are combined into a cathode-limited full cell, which is subjected to prolonged cycling at 40 degrees C, revealing a very stable capacity of about 140 mAhg(-1) and retention above 99% over 400 cycles. The electrode/electrolyte interface is further characterized through a combination of electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) investigations upon cell cycling. The remarkable performances reported here definitively indicate that IL-based lithium ion cells are suitable batteries for application in electric vehicles.