Preparation Of Nano-fiber Nonwoven By Electrospinning And Its Application In Lithium-sulfur Batteries

Due to the environmental problems caused by energy consumption,people’s demand for high-energy batteries is increasing.Lithium-sulfur battery has become a boom for researchers because of its high energy density(2600 Wh kg^-1).But its own defect resist the commercialization of lithium-sulfur batteries,such as sulfur and the final discharge products of lower conductivity,the cycle of the positive volume of the expansion effect and long-chain polysulfide "shuttle effect",which have caused sulfur Loss of positive electrode active material.The lower utilization rate of active substances affects its electrochemical performance and restricts the practical application of the battery.In this paper,the intercalation modification study was carried out for the problems such as lower sulfur loading rate and high polysulfide shuttle in the current lithium-sulfur battery.Non-woven carbon nanofibers,Al₂O₃/C composite nanofibers and Ni / C composite nanofibers were prepared by electrospinning.The effects of different calcination temperatures and different additions of nickel and aluminum salt were carried out.Electrochemical properties were investigated and a positive electrode with a sulfur loading rate of 70% was prepared.The main findings are as follows:The nonwoven fabric carbon nanofibers were prepared by a simple one-step electrospinning method and used as a functional intercalation in a rechargeable lithium-sulfur battery.Non-woven carbon nanofiber functional intercalation is placed between the sulfur positive and the separator,inhibiting the sulfide and polysulfide shuttle.Lithium-sulfur batteries with carbon nanofiber non-woven functional intercalation show excellent performance in terms of capacity utilization,reversibility and magnification performance.The specific capacity of the discharge is still above 760 mAh g^-1 after 200 cycles of cycling at 1C,which is significantly better than the lithium-sulfur battery(200 cycles,only 260 mAh g^-1 at 0.5C).The improvement of electrical properties is due to the three-dimensional structure of carbon nanofibers non-woven.functional intercalation,which can provide a good stable conductive network structure,in the process of charging and discharging to reduce the phenomenon of polysulfide migration shuttle.The Al₂O₃/C composite nanofiber nonwoven fabric with different calcination temperature and Al salt addition was prepared by one-step electrospinning method.The effect of functional intercalation on the electrochemical performance of lithium-sulfur battery was studied.The results show that the composite nanofiber nonwoven fabric with 1 g of Al salt has a better cycle performance at 900 ℃,the initial discharge capacity is 1360 mAh g^-1 at 1C,200 lb is still nearly 1000 mAh g^-1 discharge specific capacity,and better than the same temperature of the C nanofiber non-woven intercalation(1C cycle under the cycle of 200 cycles of discharge capacity at 760 mAh g^-1);And the magnification performance is also significantly better than C nano fiber nonwoven fabric intercalation.The results show that the polar metal-oxygen bond in Al₂O₃/C composite nanofibers can effectively inhibit the shuttle of polysulfide.Ni / C composite nanofiber nonwoven fabric was prepared by electrospinning.The effects of different calcination temperature and Ni salt addition on the electrochemical performance of lithium-sulfur batteries were studied.It was found that the composite nanofibers with 1g of Ni salt added excellent cycling performance at 900 ℃.The initial discharge capacity at 106C is 1062 mAh g^-1,and the stable discharge specific capacity of 910 mAh g^-1 is maintained after 200 cycles.The discharge capacity of 695 mAh g^-1 is maintained even at 2C magnification.The results show that the Ni / C composite nanofiber nonwoven fabric can be used as a new secondary current collector to provide a good electron transport channel for the active material,thus improving the cycle and rate performance of the lithium-sulfur battery.While its porous network structure can inhibit the diffusion of polysulfide.