Study On Preparation And Design Of The Cathode Materials Based Lithium Sulfur Battery

In recent years,with the increasing energy crisis and the development of electronic and electeric equipment,research of clean sustainable energy has gradually become a research hotspot.Lithium sulfur batteries has been recognized as one of the most development prospect of the energy storage system due to its high theoretical specific capacity?1675m Ah/g?and high theoretical energy density?2600 Wh/kg?.At the same time,the elemental sulfur resources is abundant,low cost and environmentally friendly.However sulfur and Li₂S all have low conductivity,the polysulfide will dissolved in the electrode during the electrochemical reaction,resulting in "shuttle effect",and volume expansion of sulfur electrode during charge and discharge cycle are serious influence the electrochemical performance of lithium sulfur batteries.This paper from the perspective of sulfur carbon composite materials to solve the above problems,the main experiment has the following three aspects.1.We report a simple and low-cost for porous carbon with SiO₂ contain using biomass waste materials rice husk.Then the carbon materials are used as the conducting matrix for sulfur to form carbon/sulfur composites,and test the electrochemical properties.This SiO₂ contain carbon materials both have the porous and the chemical adsorption to limit the loss of the active material sulfur.2.We report a simple and low-cost for porous carbon with nanosheets structure using biomass waste materials corn cob.Then the carbon materials are used as the conducting matrix for sulfur to form carbon/sulfur composites,and test the electrochemical properties.The carbon material has the highly porous structure of the two-dimensional carbon nanosheets,which not only continue pathway for rapid electron and ion transportation,but also restrain polysulfides.When it applid as cathodes for Li-S battery the composites showed excellent cycle stability and rate performance in the SA as binder.3.In this paper,we prepared a series of carbon materials which have 3D interconnected hierarchical porous carbons?HPCs?with desirable surface functionalities through a simple activation from a cheap and natural polymer material.The resulting HPC/S composites exhibit outstanding electrochemical performance as cathode materials for Li-S batteries.At the same time HPCs not only can accommodate volume expansion of sulfur but also ensurethe content of sulfur.The above experiment provides a simple operation and and easy to batch production.This study on the relationship between the microstructure and the electrochemical performance can be a good guide to the effective design of the carbon matrix materials.4.This work we preparation a novel metal,binder-free,flexible N-doped carbon matrix as sulfur host and current collector.The relationship between porosity and electrochemical properties of electrode structure is discussed,To compared with the traditional method,this method is simple and rapid,by adjusting the electrode porosity and chemical bonding double effect,obtained with high energy density and positive electrode materials have good electrochemical performance,which is positive significance for the commercialization of lithium sulfur battery.