The Role of Ion Size and Electronic Character in Zwitterionic Electrolytes for Transport of Lithium-Metal Ions*

Long-range Li-ion transport in most solid polymeric electrolytes occurs via a vehicular mechanism that couples polymer segmental dynamics to electrolyte performance. Consequently, the majority of successful polymer electrolyte candidate materials are extensively plasticized, representing a tradeoff between desirable mechanical properties and electrochemical functionality. We have recently demonstrated zwitterionic polymer electrolytes (PZIs) that transport Li+ ions via a superionic mechanism that enables high Lithium salt conductivitities (10-3 S/cm) and transport numbers (t+~0.67) despite modest glass transition temperatures (>0°C), however the chemical design features that contribute to this mechanism are poorly understood. In this talk I will develop design rules for fast ion transport in PZIs investigating the factors of tethered ion size and electronic character. These investigations lead to the discovery of universalities connecting the design of PZIs and their small molecule ZI counterparts.