Study On Optical Fiber Grating Electrochemical Sensor For Monitoring On-line The State Of Charge Of Supercapacitors

Electrochemical energy storage devices(such as supercapacitors),which are considered as the highest energy storage efficiency and the most promising energy storage equipment,are widely used in the fields of clean electric power,electric vehicle,mobile medical treatment,portable electronic equipment and so on.How to accurately monitor the real time energy storage and health state of the supercapacitors is of great significance for understanding its working mechanism,analyzing and solving its decay causes,and can also find the energy storage devices in time to reduce the energy storage efficiency and avoid the major accidents caused by the endurance interruption of the energy storage devices.The existing testing technologies of electrochemical energy storage devices include cyclic voltammetry,galvanostatic charge-discharge test,and so on.These technologies do not have realtime and on-line monitoring capability.In recent years,researchers have also proposed in situ detection techniques,including transmission electron microscopy or cryo electron microscopy,but they are not suitable for application in the field because of their large volume and expensive price.Traditionally,electrochemical surface plasmon resonance(EC-SPR)technology is based on prism optical structure.Take account of the huge volume of prism,it cannot be used to measure in the narrow space,which restricts the practical development.Based on the above research background,this thesis has carried out the following two parts:(1)A high-precision electrochemical Plasmonic tilted fiber grating(TFBG)sensing method: We have developed a new ultra-sensitive sensing technology based on plasmonic enhanced TFBG.This technology converges the high energy dense resonance field to the optical fiber,which is same as hair in size.It can ultra-accurately detect the free electron and local ion density in the nanometer scale of the electrode surface of the energy storage devices,so as to detect the working state of the devices in real time and in situ.Finally,the information of important working parameters,such as current,potential,capacitance and temperature,is prepared to provide users with comprehensive information on health status of energy storage devices.(2)In situ and real-time detection of the charge state of the supercapacitors: we first time use the aforementioned electrochemical plasmonic TFBG sensor for monitoring the charge state of the supercapacitors in situ and real time.According to the different charging and discharging modes in the actual application of supercapacitors,experimental verification and depth analysis are carried out to prove the feasibility of this method.In addition,using the long distance transmission capacity of optical fiber,the method can also be used in the field of ocean tide,ocean wind power,desert solar energy and so on.It provides an important means for the development and utilization of new energy in the world.