Effect of Film-Forming Additive in Ionic Liquid Electrolyte on Electrochemical Performance of Si Negative-Electrode for LIBs

Abstract

1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (EMI-TFSA) is one of the promising ionic liquids as electrolyte solvent to enhance the electrochemical performance of Si electrode for Li-ion batteries (LIBs) because of its low viscosity and high conductivity. However, it has low stability against reduction and its reductive decomposition product inhibits Li + insertion to electrodes, leading to poor cycling stability. To exert a potential of EMI-TFSA, we employed vinylene carbonate (VC) as film-forming additive. Si electrode exhibited very high cycling stability and rate capability in 20 vol.% VC-added EMI-TFSA-based electrolyte. In addition, by replacing TFSA anion with bis(fluorosulfonyl)amide (FSA) for Li salt and ionic liquid solvent, an excellent cycling performance and outstanding rate capability was achieved. VC cannot only fabricate a good surface film but also lower the interaction between Li + and FSA-, providing smooth desolvation of FSAto obtain better high-rate performance. Non-flammability of the VC-added electrolytes was confirmed by fire resistance test in closed-system: no ignition was observed even at 300 • C. Consequently, we found that mixture electrolyte consisted of EMI-based ionic liquid and VC, especially 1 M LiFSA/EMI-FSA with 20 vol.% VC, is a prospective candidate for simultaneously enhancing the electrochemical performance of Si electrode as well as safety of LIBs.

Pyrrolidinium Containing Ionic Liquid Electrolytes for Li-Based Batteries

“…Examples of ILs that have been identified as suitable electrolytes include: ammonium , pyridinium [47][48][49][50], piperidinium , imidazolium [78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97] and pyrrolidinium. Each cation offers favorable properties, for example, piperidinium ionic liquids possesses non-flammability, large electrochemical window (−3.8 to 2.5 V vs. Pt) [98], and inherent conductivity, which make them suitable for use as an electrolyte solvent in electrical energy storage devices [51,52].…”

“…Extensive research has been carried out on 1-ethyl-3-methylimidazolium-based ILs. This IL has shown compatibility with a wide range of cathode and anode materials in both its liquid [ 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 ] and polymer gel form [ 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 ]. Other imidazolium-based ILs have been synthesized and characterized, and their physicochemical properties were determined [ 108 , 109 , 110 ].…”

Electrochemical Properties of Silicon/C Composite with Porous Carbon Designed Using α-Cyclodextrin and Surfactant

“…This observed lithiated/delithiated profiles were agreement with that of the majority of Si anodes reported. [13][14][15][16][17] This suggested that the lithiation reaction of Si/ CyDC-SA included not only the insertion reaction of Li into carbon but also the alloying reaction between Li and Si. The Si utilization factor in the lithiation/delithiation process was calculated to be 26% of Si nanoparticles contained in Si/CyDC-SA.…”

Effect of FSI Based Ionic Liquid on High Voltage Li-Ion Batteries

“…The wide electrochemical window of the ionic liquid can broaden the working voltage of the LIBs [21][22][23]. Ionic liquids as electrolyte additives are known to enhance the electrochemical performance of lithium ion batteries (LIBs) [24][25][26][27][28][29][30][31]. Therefore, the problem of high-voltage oxidative decomposition is expected to be solved by using ionic liquid electrolyte additive [32][33][34].…”