Stability liquid electrolytes

According to Tarascon and co-workers, the swelling of PVdF—HFP by liquid electrolytes was never complete due to the semicrystalline nature of the copolymer, which tends to microphase-separate after the activation by electrolyte. On the other hand, it is those crystalline domains in the gelled PVdF—HFP that provide mechanical integrity for the resultant GPE. Thus, a dual phase structure was proposed for the Bellcore GPE by some authors, wherein the amorphous domain swollen by a liquid electrolyte serves as the ion conduction phase, while tiny crystallites act as dimensional stabilizer. 

The use of quasi-solid-state electrolytes usually reaches the goal of a superior thermal stability with respect to liquid electrolytes cells can survive prolonged periods (accelerated aging of 1000 h) at relatively high temperatures (55-80°C) under... 

If, however, solid electrolytes remain stable when in direct contact with the reacting solid to be probed, direct in-situ determinations of /r,( ,0 are possible by spatially resolved emf measurements with miniaturized galvanic cells. Obviously, the response time of the sensor must be shorter than the characteristic time of the process to be investigated. Since the probing is confined to the contact area between sensor and sample surface, we cannot determine the component activities in the interior of a sample. This is in contrast to liquid systems where capillaries filled with a liquid electrolyte can be inserted. In order to equilibrate, the contacting sensor always perturbs the system to be measured. The perturbation capacity of a sensor and its individual response time are related to each other. However, the main limitation for the application of high-temperature solid emf sensors is their lack of chemical stability. 

However, the presence of liquid electrolyte has the problems of leakage, robust sealing, and device stability, thus results in limited commercialization. Quasi-solid-state and solid-state DSSCs based on nonvolatile ionic liquid or organic hole-conducting material/polymer as the electrolyte are, therefore, developed to circumvent the sealing problem. 

A pilot line for producing large numbers of small modules also provides important knowledge for the future production of much larger solar panels for outdoor use, where the long term cost target should be less than 1 euro/Wp. The most important issue to be solved is intrinsic stability and particularly thermal stability. A major concern remains the use of a liquid electrolyte. Practical experience will have to demonstrate feasibility. 

Stability of electrodes in liquid electrolyte solutions, corrosion problems. Especially interesting is the electrochemistry of active metals. 

O Regan and Gratzel, 1991). In these cells, a dye is incorporated in a porous inorganic matrix such as Ti02, and a liquid electrolyte is used for positive charge transport. This type of cell has a potential to be low-cost. However, the efficiencies at present are quite low, and the stability of the cell in sunlight is unacceptable. Research is needed to improve performance in both respects. 

---