Dry polymer electrolytes

Noncoordination anions with extensive charge delocalization have been very suc-cesful in enhancing the performance of dry polymer electrolytes. Examples of these are given in Table 1. 

The temperature dependence of the conductivity of the various classes of polymer electrolyte discussed above is summarized in the Arrhenius plots in Fig. 7.23. While a wide choice of materials is now available, it is important to note that improvements in conductivity are generally accompanied by losses in chemical stability and by increases in reactivity towards the lithium metal electrode. Successful development of rechargeable LPBs is therefore likely to be linked to the use of the so-called dry polymer electrolytes, namely pure PEO-LiX systems. This necessarily confines the operation of LPBs to above ambient temperatures. This restriction does not apply to lithium ion cells. 

Positive intercalation electrode-lithium anode (lithium-metal) with a dry polymer electrolyte layer. 

The first and the second categories, the latter of which (PVDF-based systems) does not properly belong to the class of polymer electrolyte batteries, are covered in Chap. 35. In this chapter, the attention is focused on the lithium metal, dry polymer electrolyte systems. 

TABLE 34.17 Major Lithium Metal Anode, Dry Polymer Electrolyte (PEO-based), Battery Technology Development Projects (from Ref. 50)... 

The last remark is about the future prospects. Most of the text presented here deals with lithium cells and lithium electrolytes. However one has to keep in mind that most of the knowledge earned on these systems can be transferred easily (if not directly sometimes) into different ones. A good example could be sodium cells. If one day humankind faces a scarcity of lithium (http //www.meridian-int-res.com/Projects/Lithium Problem 2. pdf) it will have to move towards sodium cells. However, the chemistry of lithium and sodium electrodes with liquid electrolytes is quite different. On the other hand aU the examination methods and experimental setups developed for dry polymer electrolytes apply to lithium as weU as sodium cells. There are also some common conclusions (West et al. 1989). At the time this book is being written, revival of research on sodium electrolytes and... 

Polymer-based ion conducting materials have been of great interest to researchers in the field of lithium batteries since Armand et al proposed the use of poly(ethylene oxide) (PEO)-Li salts as a solid polymer electrolyte (SPE). In this application, the polymer electrolyte functions as a mechanical separator between the two electrodes and also as the ionic conductor. Polymer electrolytes are used in the form of thin films and may be either dry (organic solvent-free) or plasticised. A high specific energy density can be reached at medium temperature using a dry polymer electrolyte and lithium metal as the negative electrode. 

Concept of the all-solid battery using a dry polymer electrolyte and metallic lithium anode. 

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