Synthesis Process Research On Layer Network Structure Sulfur Carbon Cathode Materials

Lithium sulfur battery has become the next generation energy storage system with great application prospect due to its great advantages in theoretical capacity and energy density.With the continuous deepening of research in recent years,in view of the large-scale technology development are faced with the problem are also increasingly prominent,taking the preparation technology of positive electrode materials as an example,due to the excessive addition of inactive substances,the sulfur content is greatly reduced,resulting in a low volume energy density.At the same time,the complex preparation process and limited production efficiency make the technology conversion and application very difficult.This paper aims at the synthesis of sulfur-carbon materials with high sulfur content and high preparation efficiency: Firstly,the layered structure sulfur carbon(Super P,denoted as "SP")material was prepared by rolling process.By changing the deformation degree and sulfur-carbon ratio,the technological feasibility of the preparation of layered structure sulfur-carbon anode material by calenderization method was discussed based on the morphology and electrochemical properties;Secondly,the reticular sulfur carbon(including SP)material was synthesized by in-situ carbonization with sucrose coating,and the feasibility of in-situ carbonization to synthesize the reticular sulfur carbon(including SP)positive electrode material was determined by changing the coating ratio;Finally,combining the process route of rolling process and sucrose-coated in-situ carbonization method.On this basis,orthogonal experiments were introduced to discuss and analyze the synthesis process routes and appropriate process parameters of the layered structure sulfur-carbon anode materials The main results are as follows:(1)Calendering deformation degree significantly affects the sulfur layer thickness and layer spacing of layered sulfur/carbon(sp)ratio cathode material,andsulfur-carbon(sp)ratio significantly affects the density of carbon layer.Under the conditions of mass ratio of sulfur to carbon(sp)of 9.5:0.5 and deformation degree of90 %,the sulfur-carbon cathode material with clear and compact layered structure can be obtained by calendering process.(2)The coating ratio significantly affects the continuous integrity of the in-situ carbonization-coated sulfur network structure.Under the conditions of carbon/sulfur mass ratio =4% and carbon(sp)/sulfur mass ratio = 9.5:0.5,the carbon(sp-containing)coated sulfur cathode material with clear and continuous network coating structure can be reliably synthesized by adopting the treatment process of sucrose coating and in-situ carbonization(100 ?~120 ?).(3)the synthesis process route of sulfur carbon(sp-containing)cathode material with laminated structure was proposed,which was formed by sucrose coating and in-situ carbonization at 100 ?~120 ? to form a continuous and uniform network coated sulfur structure,and then further obtained by calendering.The suitable technological parameters are: deformation degree 90 %,deformation temperature60 ?,rolling times 1,carbon/sulfur mass ratio=4 %,sulfur /carbon(sp)& carbon mass ratio = 9.5:0.5.The prepared layer net structure sulfur carbon(containing sp)positive electrode material has a sulfur loading rate of about 95 %,its first discharge specific capacity is 1150 mAh/g(0.1 C rate),the discharge specific capacity for 100 cycles at 0.5 C rate is 566.1 mAh/g.