Preparation And Energy Storage Properties Of Carbon-based Membrane Modified By Excimer Ultraviolet Light

In order to meet the ever-increasing long-term endurance requirements of portable electronic devices and electric vehicles,the exploration of high-energy storage systems becomes more urgent.Among various schemes,lithium-sulfur battery is expected to become an efficient new generation of energy storage system due to its high theoretical specific capacity(1675 mAh g^-1)and high energy density(2600 wh kg^-1).However,there are some main factors that have resctricted the rapid development of lithium-sulfur battery,the dissolution and migration of polysulfides during charge and discharge process,the extremely poor conductivity of sulfur and the increase in volume.Based on the review of domestic and foreign research on lithium-sulfur battery interlayers and separators,this paper aims at the above problems of lithium-sulfur batteries,combined with the functionalization of the theoretical knowledge system,constructs lithium-sulfur battery intercalation layers with different functional structures,and effectively improve the stability and safety of high-performance lithium-sulfur batteries.(1)Preparation and energy storage properties of ZnO interlayer(EUN-ZnO/CNF)on carbon nanofibers modified by excimer ultraviolet light.The acrylic fiber-based carbon nanofiber is obtained by dissolving the acrylic fiber yarn into a spinning solution,electrospinning,carbonization,and other processes.Placed the carbon nanofiber in an aqueous solution containing Zn Cl₂ and subjected to excimer ultraviolet light irradiation for 20 min.After drying and annealing,the surface of carbon nanofiber was loaded with ZnO particles.Then,the EUN-ZnO/CNF was applied to a lithium-sulfur battery and the battery could block and adsorb polysulfide effectively.The battery had a first-cycle discharge specific capacity of 1388.3 mAh g^-1 at 0.2 C.After 200 cycles,the battery had a specific capacity of 780.4 mAh g^-1,the average coulombic efficiency was as high as 99.6%.The ZnO particles supported by excimer ultraviolet light irradiation can be used as active sites for adsorbing polysulfides,and the modified interlayer improves the lithium-ion diffusion rate in the battery.(2)Preparation and energy storage properties of graphene membrane modified by excimer ultraviolet light(EUV/graphene-separator).The modified separator,irradiated by excimer ultraviolet light,with the graphene powder loaded on the glass fiber by vacuum filtration,can effectively block the polysulfides diffusion and significantly improve the utilization rate of active materials;assembled into a lithium-sulfur battery,the first discharge specific capacity is as high as 1164 mAh g^-1 at 0.2C.After 300 cycles,the specific capacity can still maintain 640.5 mAh g^-1.This modified separator not only guarantees the efficient migration of lithium ions,but also inhibits the shuttle effect of lithium-sulfur batteries effectively.