Preparation And Properties Of Electrodes And Electrolytes For Flexible Transparent Supercapacitors

Flexible transparent energy storage devices endow new properties and function for traditional energy storage technique,bring portable convenience and novel sensory experience,and meet the development needs of flexible electronics.Now they have become a new research direction within the interdisciplinary field of new energy and flexible electronics.Flexible transparent supercapacitors（FTSCs）are a research focus among flexible transparent energy storage devices because they inherit the merits of high power and long cycling stability of the traditional supercapacitors,and are easy to be prepared.But up to date,only several types of transparent electrodes and transparent electrolyts existed,especially the lack of solid ransparent electrolyts,hinder the development of FTSCs.This thesis will explore new solid flexible transparent electrolytes,and prepare suitable flexible transparent electrodes to match the electrolytes,then try to assemble them into all-solid FTSCs,finally develop high-performance electrode and electrolyte materials for FTSCs.The main progresses are summarized as follows:1.Polyvinylidene fluoride（PVDF）and ionic liquid（IL）composite flexible transparent solid electrolyte is prepared via blade coating method.This solid electrolyte film with IL/PVDF mass ration of 1:2 exhibits the optimal comprehensive properties,including 73.6%transparency at 550 nm and charge transfer resistance of 229.7Ω.The symmetrical supercapacitor assembled using SWCNTs/ITO/PET as transparent electrodes and PVDF/IL as transparent solid electrolyte,shows a transparency of 44.6%,and an area specific capacitance of 15μF cm^-2 at a scan rate of 50 m V s^-1.The device can maintain the 84%of the initial capacitance when suffered a bending operation at an angle of 180°,indicating the excellent flexibility and mechanical stability.The devices suffer a small degradation after 2000 charge-discharge cycles with a capacitance retain of 94.6%,exhibiting outstanding cycling stability.These results indicate the great potential of PVDF/IL transparent solid electrolytes.2.PEDOT:PSS/SWCNT/PET transparent electrodes are prepared by spraying coating method,and they are used to constructing FTSCs together with PVDF/IL solid electrolyte.The device shows an area specific capacitance of 0.47μF cm^-2 at a scan rate of 50 m V s^-1.Such a low capacitance should result from the low diffusion rate of IL in PEDOT:PSS film.When the PVDF/IL solid electrolyte is replaced by PVA/Li Cl gel electrolyte,the fabricated FTSCs could deliver an area specific capacitance of 0.047μF cm^-2 at a scan rate of 50 m V s^-1.And they also suffer a small degradation after 2000charge-discharge cycles and retain a 93.9%capacitance of its initial value,suggesting their high cycling stability.Hence the FTSCs based on PEDOT:PSS electrodes prefer to use inorganic salt electrolyte.