Research On The Structure Regulation And Sodium Storage Mechanism Of The Negative Electrode Material Of Bio-carbohydrate Carbon-based Sodium Ion Battery

The development of lithium-ion batteries has improved people's living conditions.However,due to the consumption of lithium resources and the safety issues of lithium ion batteries,their application in large-scale energy storage is limited.People have also shifted the focus of research and development to systems based on sodium ion batteries.The key to the current research of sodium ion batteries lies in the development of high-performance anode materials.There are a variety of different energy storage mechanisms reported for anode materials,and the most eye-catching is the anode materials based on carbon-based materials?pure carbon materials and carbon-based composite materials?.For pure carbon materials,it has good electrical conductivity and cycle stability,and can further improve sodium storage performance through a series of structural adjustments.However,how to construct the relationship between the intrinsic microstructure of carbon materials and the mechanism of sodium storage still needs further exploration.For carbon-derived composite materials,the transition metal sulfide is taken as an example.By uniformly compounding with carbon,high capacity is ensured while stability is also guaranteed.However,high cost and compounding are still involved in current research Difficulties and problems such as sulfur source pollution.To this end,in this paper,based on carbon-based materials derived from biological sugars,through a series of structural adjustments and analytical characterization to explore the effective means of improving the sodium storage performance of carbon-based materials,mainly conducted the following research:?1?Using more conventional biological sugar glucose as the carbon source,a carbon material rich in intrinsic defects was prepared using a template-assisted method.By characterizing its microstructure and sodium storage performance,the inherent intrinsic defects in carbon materials were found It can be used as the active site for sodium ion adsorption.The prepared carbon material maintains a high capacity of 221 mAh·g^-1 through100 cycles at 1 A·g^-1.It can also cycle more than 5000 cycles even at a high current density of 10 A·g^-1,which is higher than most reported carbon materials.Further theoretical calculations also prove that the carbon model with a defective structure has a relatively high sodium ion adsorption energy??Ea?,which is beneficial to the rapid charge storage of sodium.This work improves the sodium ion adsorption capacity of carbon materials through structural defect strategies,and has a guiding significance for the design of carbon nanomaterials with high sodium storage characteristics.?2?In order to solve the defects of poor dispersion of sulfide in carbon matrix,high compound cost and serious pollution,carrageenan biopolysaccharide with sulfonate group was selected as the green carbon source and sulfur source,using carrageenan and metal nickel ions Ni₃S₄/CAs,a composite material with nickel sulfide uniformly embedded in the carbon matrix,was prepared by complexation.The uniform coating of the carbon matrix is realized,and the coating content of the carbon is further adjusted.The resulting composite material Ni₃S₄/CAs-1 has the most superior sodium storage performance.After 100 cycles at a current density of 1 A·g^-1 It has a high capacity of 297 mAh·g^-1,and the active particles are evenly distributed with a size of about 30 nm.This experiment provides a simple and economical green synthesis method for preparing carbon/metal sulfide composite anode materials with excellent performance.