Preparation Of PTFE/Activated Carbon Composite Electrode And Application For Capacitive Desalination

Capacitive deionization(CDI)is a low-energy,environmentally friendly technology for desalination of brines.As the core component of the CDI system,the electrode plays a decisive role in the desalination of the CDI system.As a part of the electrode forming components,the binder has a great influence on the performance of the electrode,which in turn affects the CDI desalination performance.In this paper,polytetrafluoroethylene(PTFE)was selected as the binder,KH550 and PVDF were introduced as composite binders together,and the activated carbon electrodes were prepared by spraying and coating methods,and the possibility of its application for CDI was discussed.The electrode performance was characterized by rheology,contact angle,resistivity,SEM,BET,electrochemical test and other methods,and its influencing factors were analyzed.For the PTFE/KH550 composite binder,by changing the amount of KH550 in the slurry and the number of sprayed layers,the effect of molding conditions on the performance of the sprayed electrode was explored.The results show that the sprayed electrodes are hydrophobic as a whole.Adding an appropriate amount of KH550 can significantly improve the adhesion of the electrode,so that the electrode has good conductivity and certain strength.At this time,the electrode has a relatively high specific surface area,which is 856.4 m~2/g,and the area specific capacitance is 0.396F/cm~2.With the increase of KH550 dosage,the electrode stability becomes worse.When the number of spray layers is less than 3,the electrode is relatively stable,but not strong enough for desalination applications.The electrode with 3-4 layers has larger specific surface area and area specific capacitance.When 4 layers are sprayed,the desalination amount of the electrode in the desalination cycle reaches 9.401 mg/g.The 50 cyclic voltammetry results show that with the increase of the number of sprayed layers,the stability of the electrode becomes worse.The results of desalination experiments show that the amount of KH550 is 2-4 g,and the electrode sprayed with 3-4 layers shows good desalination performance.For PTFE/PVDF composite bonding,the effects of PTFE/PVDF ratio in slurry and solvent dosage on the performance of coated electrodes were investigated.The results show that the coated electrode is hydrophilic and has good stability.After 50cyclic voltammetry,the specific capacitance only decreases by 7.35%,and the maximum specific capacitance can reach 141.78 F/g.With the increase of the specific gravity of PTFE or the amount of solvent,the hydrophilicity,conductivity and strength of the electrode decreased slightly,but the stability of the electrode increased slightly.The desalination results show that when the ratio of PTFE/PVDF is 5:5 and the solvent dosage is 32 m L,the electrode has good desalination performance,and the desalination amount amounted 8.567 mg/g.