TABLE OF CONTENTS A separator is necessary in primary and secondary batteries. Ion exchange membranes have been used in various cells and batteries. For example, a cation exchange membrane (prepared by radiation-induced grafting method using polyethylene film and acrylic acid) was reported to satisfy the properties required of a separator in an alkali battery. [250]
Various electric power storage methods have been practiced and are under development for load-levelling of electric power, which is storage of electric power at off-peak consumption and its release during peak consumption. This may be achieved in pumped hydroelectric storage, flywheel energy storage systems, superconducting magnetic energy storage (SMES), compressed air energy storage gas turbines (CAES-G/T), large batteries to store the electrical energy. [251] A large battery is an important candidate for electric power storage. Thus, various large batteries have been developed, including: Na-S, Zn-Cl 2, Zn-Br 2, redox flow, lithium ion, lead storage, and Ni-H 2 batteries. [251] The ion exchange membrane plays an important role in some of these batteries.
A redox flow battery is based on the use of two fully soluble redox couples that are electrochemically oxidized and reduced at inert electrodes separated by an ion permselective membrane to generate electricity. Various redox couples have been proposed. [252] [252] , [253] The Fe-Cr redox battery system is shown in Figure 6.42 as an example (emf (electromotive force): 1.0 V; anode solution: Fe 3/Fe 2+, cathode...
