Study Of In Situ Solidify Ionic Cellulose Gel Electrolyte

Dye-sensitized solar cells（DSSC）have the advantages of easy manufacturing process,low production cost,and flexible application.Generally,DSSC based on liquid electrolyte has a high efficiency,but it faces the problems of difficult packaging and low stability.Therefore,polymer electrolyte used in DSSC has been widely studied.In this thesis,cellulose-based polyurethane gel electrolytes were prepared by microcrystalline cellulose（MCC）,or MCC grafted with ionic liquid containing iodine ions,reacted with toluene diisocyanate（TDI）in the presence of liquid electrolyte.On the one hand,this kind of cellulose-based polyurethane gel electrolyte can be polymerized in situ to improve the interface contact problem.On the other hand,the ions can be better transported by the ionic liquid introduced and the flexibility of the electrolyte improved,which will be beneficial to improve the photoelectric conversion efficiency of DSSC.Firstly,in this thesis,three series of cellulose-based polyurethane gel electrolytes with different structures,PUM,PUMR and PUMG were prepared by MCC as raw material,and adding pentaerythritol（PER）and polyethylene glycol（PEG）.The effects of the amount of liquid electrolyte,the addition ratio of PER and PEG on the ionic conductivity of the cellulose-based polyurethane gel electrolyte were investigated.The results showed that the gelation time of the electrolyte was suitable and high ionic conductivity was achieved when the mass of liquid electrolyte was 4 times that of cellulose-based polyurethane.The conductivity of PUMG gel electrolyte reached 7.24 m S·cm^-1 when the molarity of PEG to MCC hydroxyl was 0.15:1.A series of PUMI cellulose gel electrolytes were prepared by MCC grafted with iodosubstituted ionic liquids.The effects of the grafting ratio of iodosubstituted ionic liquid,the cation type of iodosubstituted ionic liquid and the addition amount of pyridine to the electrolyte on the ionic conductivity of the electrolyte were studied.The results showed that the conductivity of the prepared PUMI-4-0.08 cellulose polyurethane gel electrolyte reached 8.18 m S·cm^-1 when the iodine-substituted ionic liquid grafting ratio was 0.08:1 and the grafted ionic liquid cation was 1-methylimidazole cation.DSSCs based on the four series cellulose electrolytes PUM,PUMR,PUMG,and PUMI were assembled respectively,and the photoelectric performance of DSSCs were investigated.The results showed that the photoelectric conversion efficiency of the DSSC based on PUMI-0.05-0.1cellulose polyurethane gel electrolyte was 5.10%and the total impedance was 57.93Ω.Meanwhile,it was found that the electrolyte PUMI-0.05-0.1had a good wettability to the photoanode by scanning electron micro-electron microscopy（SEM）tests.