(417e) Relationship Between Molecular Structure and Performance of Polymer Electrolytes for Lithium Batteries

Polymer electrolytes are desirable for next-generation lithium metal batteries because of their thermal and electrochemical stability against lithium metal, which would lead to safer batteries for use in consumer and industrial applications.  Block copolymer electrolytes in particular are of interest due to their ability to decouple the mechanical properties and ion transport mechanisms.  These elements need to be high in order to meet operating demands: high ionic conductivity and good mechanical rigidity to prevent lithium dendrite growth.  However, these systems are still hindered by concentration gradients; i.e., the number of effective lithium ions that carries the current is limited.  In this respect, single-ion-conducting block copolymer electrolytes provide much promise to resolve this problem.  They enable the sole conduction of lithium ions; hence, they avert detrimental battery limitations due to salt concentration gradients.  Single-ion-conducting block copolymer electrolytes, poly(ethylene oxide)-b-polystyrenesulfonyllithium (trifluoromethyl sulfonyl) imide (PEO-b-PSLiTFSI), with lithium transference numbers close to unity, were characterized for its ionic conductivity and morphology using AC impedance spectroscopy and small angle x-ray scattering, respectively.  The effect of molecular structure on ion transport in this class of polymers will be discussed.