| Vanadium redox flow battery(VRB)also can be called vanadium battery in short.It is used as energy storage battery with many advantages such as long cycles,a long service life,environment friendly as well as high power storage capacity.Vanadium battery technology has been emerged in the fields of energy storage and many researchers started to focused on the technology since it invented.At present,the research content mainly covers some aspects such as the key materials of electrolyte,ion exchange membrane,transport phenomenon in the cell and electrode performance.The research content is becoming more and more specific,but there are still some technical problems before it is applied.In this thesis,we focus on the problems of vanadium ion permeation through membrane which can’t be avoided.Mess transport with external fields applied has been studied.And the magnetic theory has been already adopted in electrochemistry field.The magnetic field effect on the permeability of vanadium ion and the effect on the electrochemical performance of vanadium redox cell has been studied in details as follows:Firstly,new types of permanent magnetic field have been applied on the vanadium battery.It is found that the magnetic field has significant effects on the permeability of vanadium ions.The direction of magnetic field plays a key role in the changing of mass transport behavior of the vanadium ion and when the direction of magnetic field is perpendicular to the electrolyte flow direction the permeability of vanadium ions can be obviously reduced.The experimental results show that the permeability of vanadium ions within the perpendicular magnetic field is decreased by about 8.27%.Consequently,the battery shows a better performance due to the reduction of the permeability of vanadium ions with magnetic intensity enlarged.Secondly,the electric field that naturally formed between the positive and negative electrode voltage of the battery could aggravate the permeability of the positive vanadium ions.However,when the magnetic field is combined with the electric field,the existence of the electric field won’t change the effect of the permeability of vanadium ions that caused by perpendicular magnetic field.The result shows that the effect on the permeability of vanadium ions that exposed to the two physical fields will be added,and won’t interfere with each other.Thirdly,according to the conclusion that obtained in the third chapter the perpendicular magnetic field can reduce the permeability of vanadium ions.In the fourth chapter of this paper,we continue to research the influence of magnetic field on the electrochemical performance for vanadium battery.We conclude that the existence of perpendicular magnetic field can help the battery to obtain a larger charge and discharge capacity and more charge and discharge cycles to achieve a longer service life.This is also consistent with the conclusion in the third chapter that existence of the perpendicular magnetic can reduce the permeability of vanadium ions.Lastly,the perpendicular magnetic field can improve the battery working efficiency based on the observation of charging and discharging test,cyclic voltammetry and AC impedance test.The battery energy efficiency is improved by 5.33% after exposed to the perpendicular magnetic field.We related the improvement of the battery efficiency to the decrease of diffusion resistance of vanadium ions in the electrolyte and the enhancement of the reactivity of vanadium ions caused by the perpendicular magnetic field. |
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