Mixing quaternary ammonium salt ionic liquids and carbonate electrolytes for LiFePO4

• Main Authors: Hui-ju Kao, 高慧如
• Other Authors: Chia-Chin Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/41674431649607961508

碩士 === 國立臺南大學 === 材料科學系碩士班 === 100 === We investigated the electrochemical properties and thermal stability of mixed electrolytes based on triethylmethylammonium bis(trifluoromethylsulfonyl)amide (N1222-TFSI) and organic solvents as ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) with LiPF6 and LiTFSI salt. The results show that the N1222-TFSI electrolyte mixed with EC/DMC has good ionic conductivity, wide electrochemical window, inhibition anodic corrosion of aluminum foil, good cycling performance, and high rate capacity. The thermal stability of the electrolytes is examined by the flammability test and thermo gravimetric analyzer (TGA). The flammability test shows that the 48 wt% N1222-TFSI in the mixed electrolyte is not ignited. The TGA analysis shows that the N1222-TFSI mixed electrolyte can reduce vapor amount when the temperature < 60 oC. The N1222-TFSI electrolyte mixed with EC/DMC has acceptable electrochemical properties and good safety for lithium ion battery. We used a mixture of experimental design, empirical models are fitted and plotted as contour diagrams, which facilitate revealing the different composition effects between the mixed N1222-TFSI. The results indicate that each component demonstrates different performances in ternary N1222-TFSI, EC and DMC components, which made a best fomular of mixed electrolyte. It is N1222-TFSI 0%, EC 33% and DMC 66% for pseudo components of ternary experimental design.