Electrochemical Properties of PP13TFSI-LiTFSI-P（VdF-HFP） Ionic Liquid Gel Polymer Electrolytes

N-Methyl-N-propylpiperidiniumbis（trifluoromethanesulfonyl）imide （PP13TFSI）, bis（triflu- oromethanesulfonyl）imide lithium salt （LiTFSI）, and poly（vinylidene difluoride-co- hexafluoropropylene） （P（VdF-HFP）） were mixed and made into ionic liquid gel polymer electrolytes （ILGPEs） by solution casting. The morphology of ILGPEs was observed by scanning electron microscopy. It was found that the ILGPE had a loosened structure with liquid phase uniformly distributed. The ionic conductivity, lithium ion transference num- bet and electrochemical window were measured by electrochemical impedance spectroscopy, chronoamperometric and linear sweep voltammetry. The ionic conductivity and lithium ion transference number of this ILGPE reached 0.79 mS/cm and 0.71 at room temperature, and the electrochemical window was 0 to 5.1 V vs. Li＋/Li. Battery tests indicated that the ILGPE is stable when being operated in Li/LiFePO4 batteries. The discharge capacity maintained at about 135, 117, and 100 mAh/g at 30, 75, and 150 mA/g rates, respectively. The capacity retentions were almost 100% after 100 cycles without little capacity fading.

Electrochemically-driven interphase conditioning of magnesium electrode for magnesium sulfur batteries

The earth-abundant magnesium metal is a kind of promising anode material due to its low reduction potential (-2.356V vs. SHE), high volumetric and gravimetric specific capacities of 3882 mAh cm-3 and 2234 mAh g_1 respectively [1]. Moreover, the magnesium anode shows high safety due to the non-dentritic electrodeposition mechanism during cycling, which is related to the strong Mg-Mg bonding and the consequent high energy barrier between the crystal boundaries of different crystal orientation [2].

N,N-Dimethyl fluorosulfonamide for suppressed aluminum corrosion in lithium bis(trifluoromethanesulfonyl)imide-based electrolytes

Effective passivation of aluminum(Al)current collector at high potentials(>4.0 V vs.Li/Li^(+))is of essence for the long-term operation of lithium-based batteries.Unfortunately,the non-aqueous liquid electrolytes comprising lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)and organic carbonates are corrosive toward Al current collector at high potentials(>4.0 V vs.Li/Li^(+)),despite their intriguing features(e.g.,good chemical stability and high ionic conductivity).Herein,we propose the utilization of N,N-dimethyl fluorosulfonamide(DMFSA)as electrolyte solvent for suppressing Al corrosion in the LiTFSI-based electrolytes.It has been demonstrated that the electrolyte of 1.0 M LiTFSI-DMFSA shows decent ionic conductivities(1.76 mS·cm^(−1)at 25℃)with good fluidities(2.44 cP at 25℃).In particular,the replacement of organic carbonates(e.g.,ethylene carbonate and ethyl methyl carbonate)with DMFSA leads to significant suppressed Al corrosion.Morphological and compositional characterizations utilizing scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS)reveal that DMFSA favors the formation of insoluble species(i.e.,aluminum fluoride(AlF_(3)))on the surface of Al electrode,which effectively inhibits continuous exposure of fresh Al surface to electrolyte during cycling.This work provides not only a deeper understanding on the Al corrosion in LiTFSI-based electrolyte but also an elegant path to stabilize the Al current collector at high potentials(>4.0 V vs.Li/Li^(+)),which may give an impetus into the development of lithium-based batteries.

Application of Film-forming Additives for Ionic Liquid Based Electrolyte

N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide was synthesized for the application in ionic liquid based electrolytes in lithium ion battery, 10% vinylene carbonate (VC) and 10% 1,3-propane sultone (PS) were added to the electrolyte system respectively as additives to improve the property of solid electrolyte interface and cyclic performance. The results of cyclic voltammetry showed that homogenous and compact solid electrolyte interface film formed on graphite electrode which was detected by observing the morphology of cycled graphite anode. Charging and discharging performance of LiFePO4/Li half cell was tested in the electrolyte with or without additives. The initial specific discharging capacities were increased to 129.4 and 123.0 mA·h/g by the addition of VC and PS, respectively, compared with that of additive-free electrolyte. The discharging retentions were 88.9% and 84.6% in electrolyte containing VC and PS after 10 cycles.