Mixed Ion-Electron Transfer Processes in Radical-Containing Polymers

Radical-containing polymers have promising application in fast-charging batteries, in which energy is stored through a combined ion-electron transfer process at the radical unit. In the battery environment the solid radical-containing polymer is swollen with the contacting liquid electrolyte. In this talk, experimental methods and theory that capture the nature of the redox mechanism are discussed. Specifically, electroanalytical techniques are applied to obtain relevant electron transfer rate constants and diffusion coefficients for comparison with Marcus-Hush theory. To examine the coupled ion-electron transfer process, electrochemical quartz crystal microbalance is utilized for thin films of radical-containing polymers during charge and discharge. With this approach, it is possible to distinguish between cation and anion transfer and to estimate the number of solvent molecules transferred. These results are discussed in the context of polymer-solvent interactions, solvent-salt interactions, and polymer segmental mobility.