Study On Structure And Composition Control Of Guar Gum-based Porous Carbon And Its Energy Storage Aponplicati

The performance of new energy storage systems,such as supercapacitors,lithium-ion batteries,and lithium-sulfur batteries,depends to a large extent on the synthesis and structural design of advanced electrode materials.As an ideal electrode material,porous carbon material has the advantages of low density,low price,controllable structure and good electrical conductivity.It is considered to be an electrode material system with great market potential.In this paper,the biomass polysaccharide-guar gum was used as the carbon source,and the porous grading structure carbon sphere was obtained quickly and efficiently by the pyrolysis effect of guar gum and metal ions in an alkaline environment through high temperature cracking and activation process.And as a matrix material,study its energy storage properties and energy storage mechanism,the main research results are as follows:（1）Study on the behavior of guar gum gel:Introduce different concentrations and different kinds of metal ions,such as Cu²⁺,Fe³⁺,Ni²⁺,Co²⁺,etc.in the guar gum solution system,and study the condensation of the mixed system in strong alkali solution.The change of gel behavior changes the difference in the selective cross-linking effect of guar gum on metal ions.The results showed that guar gum showed the strongest cross-linking selectivity with Cu²⁺,and the higher the ion concentration,the faster the gel speed.（2）Porous carbon spheres as electrode materials for supercapacitors-structural regulation and energy storage mechanism:The guar gum/Cu²⁺mixed solution was quickly added dropwise to KOH solution by instillation method,and the hierarchical structure was obtained by high temperature calcination.Carbon spheres,and carefully examined the structural regulation and formation process of carbon spheres,pore formation mechanism and electrochemical performance.The results show that the porous carbon sphere obtained by this method has a mass specific capacity of 280 F·g^-11 at a current density of 1 A·g^-1.Its excellent rate performance and cycle stability indicate that the material is a good material.Supercapacitor electrode material;（3）Nitrogen-doped porous carbon spheres as electrode materials for lithium-sulfur batteries and their electrochemical properties:using melamine as a nitrogen source,the carbon sphere precursor was obtained by the rapid condensation effect of guar gum/Cu²⁺mixed solution in strong alkali solution.The N-doped porous carbon spheres were obtained by high temperature calcination and KOH activation,and the effects of the introduction of melamine on the final product composition,pore structure and electrochemical properties were studied in detail.The results show that the obtained carbon material has a high specific surface area(2610 m²·g^-1),and the first specific discharge capacity is as high as 1243 mAh·g^-11 at a condition of 0.2 C rate,and has good cycle stability.（4）Transition metal/porous carbon composite material system as electrode material of lithium-sulfur battery and its electrochemical performance:using ammonia hydrogencarbonate as pore-forming agent,using guar gum in the presence of metal ions and strong alkali solution The rapid condensation effect,the gel block material is quickly obtained,and the transition metal/porous carbon sphere composite system（Ni/C,Co/C,Cu/C and Fe/C）is obtained during high temperature calcination.The results of electrochemical analysis show that as a lithium-sulfur battery electrode material,the composite system exhibits superior rate performance and cycle stability compared to a pure porous carbon sphere system.