Villarreal Jahaziel, Orrostieta Chavez Roberto, Chopade Sujay A, Lodge Timothy P, Alcoutlabi Mataz
Department of Mechanical Engineering, University of Texas, Rio Grande Valley, Edinburg, TX 78539, USA.
Department of Chemical Engineering and Materials Science and Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
Membranes (Basel). 2020 Mar 17;10(3):45. doi: 10.3390/membranes10030045.
In the present work, the effect of temperature and additives on the ionic conductivity of mixed organic/ionic liquid electrolytes (MOILEs) was investigated by conducting galvanostatic charge/discharge and ionic conductivity experiments. The mixed electrolyte is based on the ionic liquid (IL) (EMI/TFSI/LiTFSI) and organic solvents EC/DMC (1:1 /). The effect of electrolyte type on the electrochemical performance of a LiCoO cathode and a SnO/C composite anode in lithium anode (or cathode) half-cells was also investigated. The results demonstrated that the addition of 5 wt.% succinonitrile (SN) resulted in enhanced ionic conductivity of a 60% EMI-TFSI 40% EC/DMC MOILE from ~14 mS·cm to ~26 mS·cm at room temperature. Additionally, at a temperature of 100 °C, an increase in ionic conductivity from ~38 to ~69 mS·cm was observed for the MOILE with 5 wt% SN. The improvement in the ionic conductivity is attributed to the high polarity of SN and its ability to dissolve various types of salts such as LiTFSI. The galvanostatic charge/discharge results showed that the LiCoO cathode with the MOILE (without SN) exhibited a 39% specific capacity loss at the 50th cycle while the LiCoO cathode in the MOILE with 5 wt.% SN showed a decrease in specific capacity of only 14%. The addition of 5 wt.% SN to the MOILE with a SnO/C composite-fiber anode resulted in improved cycling performance and rate capability of the SnO/C composite-membrane anode in lithium anode half-cells. Based on the results reported in this work, a new avenue and promising outcome for the future use of MOILEs with SN in lithium-ion batteries (LIBs) can be opened.
在本工作中，通过恒电流充放电和离子电导率实验，研究了温度和添加剂对有机/离子液体混合电解质（MOILEs）离子电导率的影响。混合电解质基于离子液体（IL）（EMI/TFSI/LiTFSI）和有机溶剂EC/DMC（1:1）。还研究了电解质类型对锂阳极（或阴极）半电池中LiCoO阴极和SnO/C复合阳极电化学性能的影响。结果表明，添加5 wt.%的丁二腈（SN）可使60% EMI-TFSI 40% EC/DMC的MOILE在室温下的离子电导率从14 mS·cm提高到26 mS·cm。此外，在100 °C的温度下，含5 wt% SN的MOILE的离子电导率从38 mS·cm增加到69 mS·cm。离子电导率的提高归因于SN的高极性及其溶解各种盐（如LiTFSI）的能力。恒电流充放电结果表明，使用MOILE（不含SN）的LiCoO阴极在第50次循环时比容量损失39%，而含5 wt.% SN的MOILE中的LiCoO阴极比容量仅下降14%。向含SnO/C复合纤维阳极的MOILE中添加5 wt.%的SN可提高锂阳极半电池中SnO/C复合膜阳极的循环性能和倍率性能。基于本工作报道的结果，可以为锂离子电池（LIBs）未来使用含SN的MOILE开辟一条新途径并带来有前景的成果。
