Research On The Preparation Of Sulfurized Polyacrylonitrile Cathode Materials And Its Electrolyte

In the next generation of battery devices,lithium-sulfur batteries have attracted more attention due to their high theoretical energy density.Sulfurized polyacrylonitrile is a sulfur-containing cathode material with a non-dissolving mechanism which has good cycle performance and high discharge specific capacity.In order to build a lithium-sulfur battery with high performance and long cycle life,this dissertation mainly focuses on the preparation of sulfurized polyacrylonitrile and the development of highly concentrated electrolyte.The detail contents are listed as follows:(1)The reaction temperature,reaction time and sulfur removal conditions of the sulfurized polyacrylonitrile were investigated,and the influence law was revealed.The suitable conditions for the preparation of high performance sulfurized polyacrylonitrile were found.The results show that the sulfurized polyacrylonitrile prepared at the reaction temperature of350oC and the reaction time of 10 h has the most excellent discharge specific capacity,rate performance,and long cycle life.The sulfurized polyacrylonitrile after sulfur removal at 300℃can effectively improve the cycle life of the lithium-sulfur battery.(2)A highly concentrated ether-based electrolyte(4M LiFSI/DME)which can inhibit the growth of lithium dendrites,protect the lithium anode and further improve the cycle life of the battery.The results show that,the battery with electrolyte maintained a high reversible discharge capacity of 1299 mAh g-1 after 1000 cycles at 1250 mA g-1,about 92%of the capacity was preserved.(3)0.3M LiNO3 was used as an additive for 4M LiFSI/DME electrolyte to solve the problem of low discharge voltage and large polarization.Compared with 4M LiFSI/DME electrolyte,the discharge voltage increased by 16.7%,and the specific capacity increased by 55%at a large rate of 5000 mA g-1.