Electrolyte protection against overcharge

To overcome the poor mechanical properties of polymer- and gel-polymer-type electrolytes, microporous membranes impregnated with gel polymer electrolytes, such as PVdF, PVdF-HFP, and other gelling agents, have been developed as an electrolyte material for lithium batteries [156-166]. Gel-coated and/or gel-filled separators have some characteristics that may be harder to achieve in the separator-free gel electrolytes. For example, they can offer much better protection against internal shorts when compared to gel electrolytes and can therefore help in reducing the overall thickness of the electrolyte layer. In addition the ability of some separators to shutdown at a particular temperature allows safe deactivation of the cell under overcharge conditions. 

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