Synthesis and electrochemistry of polymer based electrolytes for lithium batteries

An overview is presented on the development of improved polymer based electrolytes during the past years. The emphasis lies on new approaches regarding chemical concepts that achieve a higher total conductivity and lithium transference number as well as an increased electrochemical, mechanical and thermal stability. With respect to the polymer chemistry, the focus is laid on siloxane and phosphazene derived systems. Topics are the chemical modification of the polymeric, cyclic and low molecular derivates of these systems, the formation of stable membranes from these by suitable cross-linking strategies and an extensive electrochemical characterization in corresponding lithium cells. Recent trends towards composite and hybrid materials are illustrated with examples and newly developed hybrid electrolytes. A particular chance for improvements comes from the design and use of stable small molecular additives in combination with optimized and electrochemically stable polymer networks. Special compounds are introduced which may act themselves as novel solvents with increased electrochemical stabilities. The relevance of chosen lithium salts for polymer electrolytes is discussed, too, and a new family of pyrazolide anions is introduced. In all cases, the electrochemical performance has been characterized by standard experimental techniques.