Preparation And Electrochemical Properties Of Carbon-based Tin Dioxide Energy Storage Composites

In the daily production and life of human beings,energy has gradually become an indispensable part of us.Due to the non-renewable fossil energy,the search for new and sustainable development of new energy sources has become the focus of research at this stage.As a key link in energy storage,the development of lithium-ion batteries and sodium-ion batteries has received increasing attention.However,the current anode materials currently available cannot satisfy the large-scale application of lithium/sodium ion batteries in the field of energy storage,regardless of their cycle stability or capacity.Therefore,the search for materials with large capacity and stable structure is the key to the preparation of lithium/sodium ion batteries with excellent electrochemical performance.The reaction mechanism of the anode electrode material of the battery with high specific capacity mostly includes the alloying process,and a large volume expansion will occur during the cycle,and the electrical conductivity is worse than that of traditional graphite.In response to the above problems,this paper takes SnO₂ with a higher theoretical capacity as the research object,improves the electrical conductivity of the electrode material through the combination of SnO₂ and carbon-based materials,and relieves the s Volume expansion of SnO₂ cycle process by designing the microstructure and hydrothermal synthesis.The experimental method was further improved to prepare fibrous materials,and the self-supporting of carbon-based tin dioxide materials was realized.It provides an experimental basis for the preparation of new high-capacity electrode materials.The main research contents are as follows:?1?Using potassium stannate and urea as precursors,hollow SnO₂ was obtained by hydrothermal method.The obtained hollow SnO₂ and Tris were mixed and sonicated,and different amounts of dopamine?PDA?were added to stir and mix to obtain SnO₂@PDA.SnO₂@NC material is obtained after calcination.The resulting SnO₂@NC composite is hollow SnO₂ inside,and a thin layer of carbon is wrapped around the outside.As the amount of PDA added increases,the carbon layer on the surface of SnO₂ will gradually become regular,but continuing to increase the content of PDA will destroy the regular carbon layer.SnO₂@NC composite material exhibits excellent electrochemical performance under high current in lithium-ion batteries.SnO₂@NC-0.05 composite material as a negative electrode of lithium-ion batteries circulates for 300 cycles at a current density of 1 A g^-1.The capacity can still reach 350 mAh g^-1,but due to the obvious agglomeration of the SnO₂@NC composite during the preparation process,the specific capacity decreased rapidly during the first 25 cycles,and did't to achieve the expected goal;?2?The graphene oxide solution and sodium stannate are mixed as a precursor and then subjected to one-step hydrothermal treatment to obtain a SnO₂/rGO composite material.The size of SnO₂ nanoparticles is changed by changing different pH.The obtained SnO₂/rGO composite material showed excellent electrochemical performance in lithium ion batteries.The SnO₂/rGO?P?-9 electrode material can maintain a specific capacity of 463 mAh g^-1 after 100 cycles at a current density of 0.1 A g^-1.The capacity retention rate after 100 cycles is 83.9%.The SnO₂/rGO?P?-10electrode material has a capacity specific capacity of 402 mAh g^-1 after 100 cycles and a capacity retention rate of 86.3%after 100 cycles.It can be seen that the effect of different pH on the capacity is not large,the reason is that the size of SnO₂ nanoparticles at different pH is not much different.The reason for the excellent electrochemical performance in lithium-ion batteries is that the flexibility of graphene itself greatly improves the expansion problem of SnO₂ during charging and discharging,and the excellent electrical conductivity of graphene itself also improves the poor conductivity of SnO₂.However,the electrochemical performance of sodium ion batteries is not good.The possible reason is that the size of SnO₂ nanoparticles is about 10 nm.Due to the large radius of sodium ion batteries,the problem of swelling cannot be effectively alleviated during cycling;?3?On the basis of the preparation of SnO₂/rGO composite materials,the size of SnO₂particles was finer after hydrothermal by changing the hydrothermal solvent of the precursor,and the sodium stannate-graphene oxide mixed solution was injected into the capillary tube for hydrothermal,The fibrous SnO₂/rGO composite material is prepared and exhibits excellent electrochemical performance in sodium ion batteries.At a current density of 0.1 A g^-1,the specific discharge capacity can be maintained at 303 mAh g^-11 after 100 cycles,and the capacity retention rate after 100 cycles is 86.6%.While exhibiting excellent electrochemical performance,self-supporting of the anode material is realized.