Synthesis And Electrochemical Performance Of Functionalized Ionic Liquids

Traditional lithium-ion battery organic electrolyte has the disadvantages such asvolatile and flammable, which brings to the lithium ion battery safety performance ofhidden dangers. Ionic liquid has the advantages of non-volatile and non-flammable, andhigh electrical conductivity in a certain temperature range. Functionalized ionic liquidsare in ionic liquids further with the introduction of functional groups on the basis ofreforming related properties of ionic liquids. In the dissertation, a new ionic liquid(PPO2TFSI) and PyrMeATFSI was synthetized and it was used as Li-ion batteryelectrolytes. The ionic liquid was investigated in terms of physical-chemical propertieselectrochemical characteristics and the compatibility with electrode.PyrMeATFSI has a low visitoy, PPO2TFSI has a big one, the room temperatureionic conductivity of magnitude is10-4, they have wide chemical window which is5.3Vand5.0V. The electrolytes PPO2TFSI+0.1mol/L LiTFSI and PyrMeATFSI+0.8mol/LLiTFSI have high tLi+,0.56and0.72respectively.Cathode LiFePO4has good symmetry of CV curve in PPO2TFSI+0.1mol/L LiTFSIelectrolytes, and it shows good performance. After20circulation, there is no attenuation.The capacity is110mAh·g-1. Except the first one, the coulombic efficiency has remainedat100%. The battery has bad rate performance. The electrolytes ofPyrMeATFSI+0.8mol/L LiTFSI has the same performance.Prepared the ionic liquid gel polymer electrolyte of PPO2TFSI and PyrMeATFSI.Cathode LiFePO4shows good cycle performance in ionic liquid gel polymer electrolyte.The first specific capacity can reach100mAh.g-1in0.1C rate at room temperature, thecoulombic efficiency is about80%or above.After20cycles, there is no obviousattenuation. EIS and SEM show that a substance exists in electrode surface, whichimprove the stability of battery.