Investigation Of Electrochemistry Performance And Mechanism Of Electrode Materials With Multi-electron Reaction

In order to improve the energy density of lithium-and sodium-ion batteries,and to meet the increasing demand for energy,electrode materials with multi-electron reaction are now extensively focused and researched.Due to the transfer of multiple electrons in the charge-discharge process,the materials usually show high specific capacity as well as energy density,and also the electrochemical processes are relatively complicated.Hence,the research of the electrochemical performance and mechanism of the materials is realistic and significant.In our previous work,we have explored the electrochemical performance of disodium rhodizonate--a kind of electrode material with multi-electron reaction,but its actual electrochemical process is not clear.Therefore,in this thesis,we firstly conducted an in-depth study into the discharge-charge mechanism of disodium rhodizonate,and proposed the detailed electrochemical process in terms of the molecular structures.Besides,we studied another electrode material with multi-electron reaction--indanthrene,including its electrochemical performance and mechanism.The concrete contents of our work in this thesis are as follows:?1?Firstly,by adjusting the mass loading of disodium rhodizonate,we preliminarily calculated out the total electron transfer number in the electrochemical process,according to the relationship between the charge transferred quantity,molar and actual mass of active material.Then,we conducted normal pulse voltammetry experiments,and obtained the values of the electron transfer number in each redox reaction.Then,combining the fine cyclic voltammetry curves of disodium rhodizonate,we proposed its actual electrochemical process in terms of the molecular structures.Finally,we carried out the electron paramagnetic resonance measurement,which demonstrated that our proposal of the electrochemical process was reasonable.The final result showed that the electrochemical process of disodium rhodizonate was a partial two-electron transferring process.?2?For the serious capacity decrement problem of the PVDF-based battery system,we applied PEDOT:PSS as the substitute of PVDF to composite it with indanthrene,and manipulated the proportion of PEDOT:PSS in the battery system.The experiment results showed that the electrochemical performance of the battery was indeed improved with the addition of PEDOT:PSS,and the practical capacity could reach 140 mA h g^-1 with good cycling stability when the weight of PEDOT:PSS in the electrode was 40%.On the other hand,we studied the electrochemical mechanism of indanthrene through several electrochemical analytical methods including infrared and X-ray photoelectron spectrum measurements.The experiment results showed that the electrochemical process of indanthrene was the redox of carbonyl.