Elevated Temperature Lithium-Ion Batteries Containing SnO₂Electrodes and LiTFSI-Pip₁₄TFSI Ionic Liquid Electrolyte

Abstract

The performance of lithium-ion batteries (LIBs) comprising SnO2 electrodes and an ionic liquid (IL) based electrolyte, i.e., 0.5 M LiTFSI in Pip14TFSI, has been studied at room temperature (i.e., 22°C) and 80°C. While the high viscosity and low conductivity of the electrolyte resulted in high overpotentials and low capacities at room temperature, the SnO2 performance at 80°C was found to be analogous to that seen at room temperature using a standard LP40 electrolyte (i.e., 1 M LiPF6 dissolved in 1:1 ethylene carbonate and diethyl carbonate). Significant reduction of the IL was, however, found at 80°C, which resulted in low coulombic efficiencies during the first 20 cycles, most likely due to a growing SEI layer and the formation of soluble IL reduction products. X-ray photoelectron spectroscopy studies of the cycled SnO2 electrodes indicated the presence of an at least 10 nm thick solid electrolyte interphase (SEI) layer composed of inorganic components such as lithium fluoride, sulfates, and nitrides as well as organic species containing C-H, C-F and C-N bonds.

Implementation of binder-free SnO2NWs@C electrode and LiTFSI-based electrolyte for high-performance lithium-ion battery

“…The lithium ion penetration rate often limits this step. In fact, the reduction rate of SnO 2 depends on the diffusion rate of lithium ions [27]. Nanowire (NW) morphology can slightly relieve volume change during lithiation/delithiation [17][18][19][20][21][22][23][24][25][26][27][28][29].…”

“…In fact, the reduction rate of SnO 2 depends on the diffusion rate of lithium ions [27]. Nanowire (NW) morphology can slightly relieve volume change during lithiation/delithiation [17][18][19][20][21][22][23][24][25][26][27][28][29]. SnO 2 NWs have been assessed as an electrode in LIBs due to their high electrolyte contact area, short diffusion pathway, and improved interface kinetics [20][21][22][23][24][25][26][27][28][29][30].…”

“…Nanowire (NW) morphology can slightly relieve volume change during lithiation/delithiation [17][18][19][20][21][22][23][24][25][26][27][28][29]. SnO 2 NWs have been assessed as an electrode in LIBs due to their high electrolyte contact area, short diffusion pathway, and improved interface kinetics [20][21][22][23][24][25][26][27][28][29][30]. The SnO 2 nanostructures can promote the reversibility of reaction 1 to obtain high capacitance [16].…”

“…Meanwhile, the presence of carbon coating as a conductive material that is electrochemically stable can maintain the structure when the volume changes due to stress caused by the lithiation/delithiation process. It can also improve the surface electrical conductivity and form a stable SEI layer [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Although carbon materials undergo low capacities, it should be noted that carbon is not an active material here, and its electrochemical performance is negligible [18][19][20][21][22][23][24].…”