An Exploration of the Role of Charge-Transfer Complexes in Polymer Electrolytes

Solid-state battery technologies may play an integral role in the shift toward a carbon-neutral society. In comparison to inorganic solid electrolytes, solid polymer electrolytes are generally cheaper, lighter, and more flexible. In addition, they impose lower interfacial impedance, and their production is easier to scale up. Recently, solid polymer electrolytes based on charge-transfer complexes (CTC) have been alleged to support room-temperature ionic conductivities >1.0 mS cm–1. Currently, the synthetic methodology is ill-defined, and an open question remains: does a unique Li+ conduction mechanism through CTC-based electrolytes exist? Here, we shed light on the reality of CTC-based solid polymer electrolytes. Through careful characterization, we describe the formation of a CTC using a thermoplastic, poly(phenylene sulfide), and an electron acceptor, tetrafluoro-1,4-benzoquinone. By harnessing molecular dynamics simulations and electrochemical evaluation, we assess the true advantages of these electrolytes in terms of ionic conductivity and oxidative stability.