The Application Of PMP TFSI Ionic Liquid As Electrolyte For Lithium Sulfur Battery

Lithium sulfur battery as a high energy density and green energy storage system,lithium sulfur battery development prospects are generally optimistic.At present,there are still many problems to be solved in the lithium sulfur battery,especially the safety of electrolyte,which is widely based on the ether solvent.This paper focuses on the ionic liquid solvent based on N-methyl,propyl pyrrolidinium bis(trifluoromethylsulfonyl)imide(PMPTFSI)as electrolyte solution for lithium sulfur battery.The main contents are listed as follows:1.The effects of different temperatures on the conductivity and viscosity of PMP TFSI ionic liquid electrolyte were tested.The electrochemical performance of the lithium sulfur battery with PMP TFSI ionic liquid electrolyte at 25 ℃,40 ℃,55 ℃and 70 ℃ was investigated.The results show that the increase of temperature can significantly improve the high viscosity and low conductivity of ionic liquid PMP TFSI,abate the charge transfer impedance of the electrolyte,reduce the internal polarization of the battery,improve the utilization of the active material sulfur,and ameliorate the electrochemical performance of the battery.However,the cycle stability of the battery will be worse when the temperature rises to 70 ℃.2.Meanwhile,the compatibility of PMP TFSI ionic liquid electrolyte with different cathode materials was also investigated.We use RGO framework materials metal nitride TiN and Co-N-C materials to study the electrochemical properties of the PMP TFSI electrolyte.The experimental results show that the electrochemical performance of RGO material in lithium sulfur battery with PMP TFSI ionic liquid electrolyte is obviously better than those of Co-N-C material and TiN material.3.To improve the conductivity and viscosity of PMP TFSI electrolyte,we add DOL-DME solvent in ionic liquid PMP TFSI electrolyte,and test its influence on the electrochemical performance of lithium sulfur battery.The ARC system was used to investigate the safety of the electrolyte with different components.The experimental results show that the presence of ionic liquid PMP TFSI in electrolyte can inhibit overcharge phenomenon of lithium sulfur battery and improve the coulombic efficiency.Meanwhile,the high thermal stability of the ionic liquid can improve the stability of the electrolyte.According to the comprehensive analysis of the safety test results and electrochemical performance of the electrolyte,the electrolyte 60PDD can improve the thermal decomposition temperature of the electrolyte to 262.69 ℃,the maximum heating rate is 0.119 ℃·min-1,and the first discharge specific capacity is 1222.8 mAh·g-1.60PDD electrolyte improves the electrolyte safety.At the same time,it also ensures the good electrochemical performance of the Li-S battery.