Ion and Polymer Dynamics in Solid Electrolytes for Sodium-Ion Batteries via Conductivity and NMR

Abstract The quality of a solid electrolyte is determined by its ionic conductivity, among other factors. The mobility of the ions is, therefore, of major relevance. The interplay between conducting ions and the polymer network was studied by wide-line NMR and ionic conductivity at specific time and length scales. Here, the electrolytes are the polymer electrolyte poly(ethylene oxide) (PEO) with the salt sodium-bis(trifluoromethanesulfonyl)imide (NaTFSI), as well as the composite polymer electrolyte PEO:NaTFSI + 50% wt NaSICON (Na3.4Zr2Si2.4P0.6O12). The experiments show a reduction in ionic and polymer chain mobility with increasing salt content. Furthermore, NaSICON particles reduce the chain and ionic mobilities as well as the ionic conductivity.