Preparation And Electro Chemical Performance Of NNH/PC/S Lithium-Sulfur Battery Composite Cathode Materials

Compared with the current lithium-ion batteries,the high energy density and specific capacity of lithium-sulfur batteries have attracted attention.Theoretically,the energy density of lithium-sulfur batteries is about 2600 Wh/kg,and the theoretical specific capacity can reach 1672 m Ah/g.Sulfur is widely coexisted in nature and belongs to environmentally friendly and non-polluting materials,which has great development prospects.In this thesis,the porous carbon/sulfur(PC/S)composite cathode material was designed and prepared to improve the electrochemical performance of lithium-sulfur batteries.The main research is divided into two parts as follows:(1)Using a waste biomass material(NRR)as a carbon source and potassium hydroxide(KOH)as an activator,a specific surface area of 2615 m2/g was prepared by carbonization activation in a high temperature environment,and the pore volume was 1.50 cm3/g of porous carbon.Porous carbon/sulfur composite material preparation Lithium-sulfur battery cathode material is applied to lithium-sulfur battery and has good electrochemical performance.At the charge-discharge rates of 0.5 C and 1 C,the specific capacity of the first turn reached 965 m Ah/g and 921 m Ah/g,respectively,and the reversible capacities after cycle 200 times were 551 m Ah/g and 522 m Ah/g,respectively.In addition,this paper also deeply studies the experiment of exploring the optimal cycle performance of lithium-sulfur batteries by changing the conditions of porous carbon temperature and alkali-carbon ratio.(2)Under the prepared porous carbon/sulfur composite material,the porous material of porous carbon and nickel-based hydroxide is firstly prepared to prepare the positive electrode material as the positive electrode of the lithium-sulfur battery,and the flocculated nickel-based hydroxide formed in situ is formed.The material(NNH)coats the porous carbon-sulfur composite.In addition to being a durable physical barrier,this flocculent hydroxide has a good ion permeability and a rich functional polar/hydrophilic group,catalytically anchoring of nickel.The composite prepared in this experiment exhibited excellent electrochemical properties.The prepared composite exhibits excellent electrochemical properties.The initial discharge specific capacity was 1206 m Ah/g at 0.2 C,and still maintained a specific capacity of up to 571 m Ah/g at a high current density of 5 C.The experimental results show that the carbon skeleton and porous structure of porous carbon can significantly improve the performance of lithium-sulfur batteries.The coating of nickel-based hydroxides can improve the cycle performance of lithium-sulfur batteries.Simple experimental protocols and high specific capacity battery data make commercial lithium-sulfur batteries possible.