The Investigation On Key Anode And Cathode Materials And Flexible Devices Of Lithium-Air Batteries

With the rapid development of society and economy,many portable electronic products have entered the daily life of people,and electric vehicles will become the mainstream of transport,which forces the energy storage system to meet higher requirements.Lithium-oxygen?Li-O₂?batteries,because of their ultrahigh theoretical capacity,are likely to become the next generation of main energy storage system and have been widespread concern around the world.However,Li-O₂ batteries are still in the initial stage of development,some key issues also need to further research and solve.The current problems are mainly focused on how to improve the energy conversion efficiency and cycle life of the cathode electrode,how to protect the lithium metal from corrosion,and how to make a reasonable design of Li-O₂ battery device so that it is really put into use.In view of the above problems,this thesis focuses on the design of cathode structure,metal lithium protection and device design.The works were carried out as follow:Inspired by the golden toad spawn process and the favourable shape and structure of the eggs,we design a binder-free,light weight,hierarchical macroporous active carbon fiber?MACF?electrode via a scalable and facile strategy.We show that template and electrospinning synthesis methods can be combined advantageously.The obtained binder-free MACF electrode holds many favorable advantages including high electrical conductivity,low density,high stability,and especially excellent mass adsorption and transport property.Unexpectedly,the obtained RuO₂ nanoparticles decorated macroporous active carbon fiber?R-MACF?electrodes demonstrate excellent electrochemical performances including high round-trip energy efficiency,good cycle stability,and especially excellent rate capability.The MACF-boosted advantages as well as the scientific understanding could be extended to other storage/conversion systems.The magnetron sputtering technique was used to explore the protection of lithium metal.Herein,the in situ deposition of metallic aluminum and lithium phosphorous oxynitride?LiPON?layer on the surface of metal lithium were proposed.The magnetron sputtering method can be used to obtain a high quality protective layer on the surface of metallic lithium.The two kinds of protective layer play a very good protective role,and greatly relieve the corrosion of metal lithium.Both of them are relatively stable,and will not damage the normal electrochemical reaction in Li-O₂ batteries.The further works could be carried out based on this useful technology and these materials.We fabricate a highly safe flexible Li-O₂?SFLO?battery,in where the innovative centralventilationstructureandthepolyimideandpoly?vinylidene fluoride-co-hexafluoropropylene?composite?PIPV?separator play significant roles.We show that the PIPV separator has good water resistance,excellent thermal stability and good ionic conductivity.In addition,the SFLO battery demonstrates excellent water and fire resistance,and effectively avoids the liquid electrolyte leakage.Unexpectedly,the obtained SFLO battery shows good flexibility and structural stability in the process of deformation.Significantly,the assembled SFLO battery can survive in water.Moreover,the SFLO batteries demonstrate long cycle lifetime,high capacity and good rate capability.This innovative design extends the practical application of Li-O₂ batteries.