Читать книгу Organic Electronics for Electrochromic Materials and Devices - Hong Meng - Страница 21

The ionic conduction medium between the electrodes and electrochromic (EC) materials is an electrolyte, which is one of the most essential active components in electrochromic device (ECD). Electrolyte provides an indispensable role as the prime ionic conduction medium between the electrodes while preventing electron conduction between the two electrodes during EC operation. The important electrolyte properties greatly affecting the EC performance are the electrolyte ionic conductivity, ion dissociation, transport rate of ion through bulk and interface, and thermal stability [1]. Electrolytes were initially reported in the early 1970s, including ceramic, glass, crystalline, and polymer electrolytes (PEs). PE was first introduced by Fenton et al. in 1973 [2] and widely applied since 1980s [3]. In the past decades, PEs attracted much attention from all over the world's researchers due to their promising applications in electrochemical storage/conversion devices.

In general, electrolytes can be classified into PEs, liquid electrolytes, ceramic electrolytes, and solid inorganic electrolytes [4–6]. Briefly, PE is a membrane composed of a dissolution of salts in a polymer matrix with high molecular weight [7]. PE is widely applied in electrochemical devices such as solid‐state batteries and rechargeable batteries, ECDs, supercapacitors, fuel cells, dye‐sensitized solar cells, and EC windows. Technologically, PEs evolved from polymer, liquid ionic conductor and solid‐state ionic conductor. PEs can be prepared by dissolving metal salts in polar polymer hosts, which could be used to replace the liquid ionic solution. Liquid electrolytes possessing high ionic conductivity have several inevitable drawbacks such as the possibility of electrolyte leakage, low chemical stability, hydrostatic pressure considerations, and difficulty in assured sealing and are unsafe for practical applications especially in scaling‐up processes [8]. Comparing with liquid electrolytes, PE has several prominent advantages, such as high ionic conductivity, safety, flexibility, wide electrochemical windows, and so on [9, 10].